Identifying a Man in the Middle (MitM) attack. All About the Man in the Middle (MitM) Attack Securing the Communication Protocol

18.10.2016 | Vladimir Khazov

The plans of the FSB, the Ministry of Telecom and Mass Communications and the Ministry of Industry and Trade to implement the provisions of the Yarovaya law in terms of intercepting and decrypting the correspondence of Russians are no longer just plans, and are already starting to be put into action by an order for the preparation of an expert opinion on the possibility of intercepting WhatsApp, Viber, Facebook Messenger, Telegram, Skype messages using MITM attacks and demonstration of a prototype of such a tool.

We wrote about the scheme of organizing a "legitimate" MITM attack in the last article. Today we will dwell in more detail on the very principle of such an attack and the methods of its implementation.

What is a MITM attack

Man In The Middle (MITM) translates as "man in the middle." This term refers to a network attack where an attacker is between the Internet user and the application they are accessing. Not in the physical plane, of course, but with the help of special software. It is presented to the user by the requested application (it can be a website or an Internet service), simulates working with it, and does so in such a way as to give the impression of normal operation and information exchange.

The target of the attack is the user's personal data, such as login credentials for various systems, bank details and card numbers, personal correspondence and other confidential information. In most cases, attacks target financial applications (client banks, online banks, payment and money transfer services), company SaaS services, e-commerce sites (online stores) and other sites where authorization is required to enter the system.

The information received by the attacker can be used for various purposes, including illegal money transfers, changing accounts, intercepting personal correspondence, buying at someone else's expense, compromising and blackmailing.

In addition, after theft of credentials and hacking of the system, criminals can install malicious software on the corporate network to organize the theft of intellectual property (patents, projects, databases) and cause economic damage by deleting important data.

A MITM attack can be compared to a postman who, during the delivery of your correspondence, opens a letter, rewrites its contents for personal use, or even, having faked handwriting, adds something of his own, and then seals the envelope and delivers it to the addressee as if nothing had happened ... Moreover, if you encrypted the text of the letter, and you want to tell the decryption code personally to the addressee, the postman will introduce himself as the addressee so that you will not even notice the substitution.

How a MITM attack is carried out

The execution of a MITM attack consists of two phases: interception and decryption.

Interception

The first stage of an attack is to intercept traffic from a user to a designated target and direct it to the attacker's network.

The most common and easiest way to intercept is a passive attack, when an attacker creates Wi-Fi hotspots with free access (no password and no authorization). The moment a user connects to such a point, the attacker gains access to all traffic passing through it, and can extract any data from it for interception.

The second method is active interception, which can be carried out by one of the following options:

IP spoofing- spoofing the target's IP address in the packet header with the attacker's address. As a result, users, instead of going to the requested URL, end up on the attacker's site.

ARP spoofing- substitution of the real MAC address of the host for the address of the attacker in the victim's ARP table. As a result, the data sent by the user to the IP address of the required host gets to the address of the attacker.

DNS spoofing - DNS cache infection, DNS server infiltration and substitution of a website address match record. As a result, the user tries to access the requested site, but receives the attacker's site address from the DNS server.

Decryption

After interception, two-way SSL traffic must be decrypted, and this must be done in such a way that the user and the resource requested by him do not notice the interference.

There are several methods for this:

HTTPS-spoofing- a fake certificate is sent to the victim's browser at the moment of establishing a connection to the site using the HTTPS protocol. This certificate contains the digital signature of the compromised application, which makes the browser accept the connection with the attacker as reliable. Once such a connection is established, the attacker gains access to any data entered by the victim before it is passed on to the application.

SSL BEAST(browser exploit against SSL / TLS) - The attack exploits the SSL vulnerability in TLS versions 1.0 and 1.2. The victim's computer is infected with malicious JavaScript that intercepts encrypted cookies sent to the web application. This compromises the "cipher block chaining" encryption mode so that the attacker obtains the decrypted cookies and authentication keys.

SSL-hijacking- transfer of fake authentication keys to the user and the application at the moment of the beginning of the TCP session. This creates the appearance of a secure connection when in fact the session is controlled by a man in the middle.

SSL stripping- Downgrades the connection from secure HTTPS to plain HTTP by intercepting the TLS authentication sent by the application to the user. The attacker provides the user with unencrypted access to the site, and he himself maintains a secure session with the application, gaining the opportunity to see the victim's transmitted data. \

Protection against MITM attacks

Reliable protection against MITM attacks is possible when the user performs several preventive actions and uses a combination of encryption and authentication methods by web application developers.

User actions:

Avoid connecting to Wi-Fi hotspots that do not have password protection. Disable the function of automatic connection to known access points - an attacker can disguise his Wi-Fi as legitimate.
Pay attention to the notification of the browser about the transition to an unprotected site. Such a message may indicate a transition to a fake site of an attacker or problems with the protection of a legitimate site.
Logout the application if it is not in use.
Do not use public networks (cafes, parks, hotels, etc.) for confidential transactions (business correspondence, financial transactions, purchases in online stores, etc.).
Use an antivirus with up-to-date databases on your computer or laptop, it will help protect against attacks using malicious software.

Developers of web applications and sites should use secure TLS and HTTPS protocols, which greatly complicate spoofing attacks by encrypting the transmitted data. Also, their use prevents interception of traffic in order to obtain authorization parameters and access keys.

It is considered good practice to secure TLS and HTTPS not only of the authorization pages, but also all other sections of the site. This reduces the chance of an attacker to steal the user's cookies at the moment when he navigates through unprotected pages after passing authorization.

Protection against MITM attacks is the responsibility of the user and the telecom operator. For the user, the most important thing is not to lose vigilance, use only proven methods of accessing the Internet, and choose sites with HTTPS encryption to transfer personal data. Telecom operators can be advised to use Deep Packet Inspection (DPI) systems to detect anomalies in data networks and prevent spoofing attacks.

Government agencies are planning to use the MITM attack to protect citizens, not harm, unlike attackers. Interception of private messages and other user traffic is carried out within the framework of the current legislation, carried out by decision of the judicial authorities to combat terrorism, drug trafficking and other prohibited activities. For ordinary users, “legitimate” MITM attacks are not dangerous.

There are almost always several ways to achieve the desired result. This also applies to the area of information security. Sometimes, to achieve a goal, you can brute force, look for holes and develop exploits on your own, or listen to what is transmitted over the network. Moreover, the latter option is often optimal. That is why today we will talk about tools that will help to extract valuable information for us from network traffic, attracting MITM attacks for this.

MITMf

Let's start with one of the more interesting candidates. This is a whole framework for man-in-the-middle attacks, built on the basis of sergio-proxy. Recently included in Kali Linux. For self-installation, just clone the repository and run a couple of commands:

# setup.sh # pip install -r requirements.txt

# pip install -r requirements.txt

Has a plugin-extensible architecture. Among the main ones are the following:

Spoof - allows you to redirect traffic using ARP / DHCP spoofing, ICMP redirects and modify DNS requests;
Sniffer - This plugin monitors login attempts for various protocols;
BeEFAutorun - allows you to automatically launch BeEF modules based on the type of OS and client browser;
AppCachePoison - Performs a cache poisoning attack;
SessionHijacking - hijacks sessions and saves received cookies in the firelis profile;
BrowserProfiler - tries to get a list of plugins used by the browser;
FilePwn - allows you to replace files sent over HTTP using Backdoor Factory and BDFProxy;
Inject - Injects arbitrary content into an HTML page;
jskeylogger - Injects a JavaScript keylogger into client pages.

If this functionality does not seem enough for you, then you can always add your own by implementing the appropriate extension.

PuttyRider

Another noteworthy utility. True, unlike all other tools considered today, it is very narrowly specialized. As the author of the project himself says, the idea to create such a utility was prompted by the fact that during the penetration tests, the most important data was located on Linux / UNIX servers, to which the admins connected via SSH / Telnet / rlogin. Moreover, in most cases it was much easier to gain access to the administrator's machine than to the target server. Having penetrated the system administrator's machine, it remains only to make sure that PuTTY is running and, using this tool, build a bridge back to the attacker.

The utility allows you not only to sniff the "communication" between the administrator and the remote server (including passwords), but also to execute arbitrary shell commands within a given session. Moreover, all this will happen absolutely transparently for the user (admin). If you are interested in technical details, for example, how the implementation in the PuTTY process is implemented, I recommend that you familiarize yourself with the author's presentation.

Quite an old utility that appeared more than eight years ago. Designed to clone sessions by stealing cookies. For session hijacking, he has basic skills in detecting hosts (in the case of connecting to an open wireless network or hub) and performing ARP poisoning. The only problem is that today, unlike eight years ago, almost all large companies like Yahoo or Facebook use SSL encryption, which makes this tool completely useless. Despite this, there are still enough resources on the Web that do not use SSL, so it is too early to write off the utility. Its pluses include the fact that it automatically integrates into Firefox and creates a separate profile for each intercepted session. The source code is available in the repository, and you can build it yourself using the following sequence of commands:

# apt-get install build-essential libwxgtk2.8-dev libgtk2.0-dev libpcap-dev # g ++ $ (wx-config --cppflags --libs) -lpcap -o sessionthief * .cpp # setcap cap_net_raw, cap_net_admin = eip sessionthief

# apt-get install build-essential libwxgtk2.8-dev libgtk2.0-dev libpcap-dev

# g ++ $ (wx-config --cppflags --libs) -lpcap -o sessionthief * .cpp

# setcap cap_net_raw, cap_net_admin = eip sessionthief

ProxyFuzz

ProzyFuzz has nothing to do with MITM attacks. As the name suggests, tools are designed for fuzzing. It is a small non-deterministic network fuzzer implemented in python that arbitrarily changes the contents of network traffic packets. Supports TCP and UDP protocols. Can be configured to fuzz only one side. Useful when you need to quickly test some network application (or protocol) and develop PoC. Usage example:

Python proxyfuzz -l -r -p

python proxyfuzz -l -r -p

The list of options includes:

w - sets the number of requests sent before the start of fuzzing;
c - fuzz only the client (otherwise both sides);
s - fuzz only the server (otherwise both sides);
u - UDP protocol (otherwise TCP is used).

The middler

A utility for carrying out MITM attacks on various protocols presented at the DEF CON conference. The alpha version supported the HTTP protocol and had three cool plugins in its arsenal:

plugin-beef.py - Injects the Browser Exploitation Framework (BeEF) into any HTTP request coming from the local network.
plugin-metasploit.py - injects an IFRAME into unencrypted (HTTP) requests, which downloads exploits for browsers from Metasploit;
plugin-keylogger.py - Inlines a JavaScript onKeyPress event handler for all text fields that will be sent over HTTPS, causing the browser to send the user-entered password character by character to the attacker's server before the entire form is submitted.

The Middler not only automatically analyzes network traffic and finds cookies in it, but also independently requests them from the client, that is, the process is automated to the maximum. The program guarantees collection of all unprotected accounts on the computer network (or public hotspot), to the traffic of which it has access. For the program to work correctly, the following packages must be installed on the system: Scapy, libpcap, readline, libdnet, python-netfilter. Unfortunately, the repository has not been updated for a long time, so you will have to add new functionality yourself.

A console utility that interactively allows you to examine and modify HTTP traffic. Thanks to such skills, the utility is used not only by pentesters / hackers, but also by ordinary developers who use it, for example, to debug web applications. With its help, you can get detailed information about what requests the application is making and what responses it receives. Mitmproxy can also help you understand how some REST APIs work, especially those that are poorly documented.

Installation is extremely simple:

$ sudo aptitude install mitmproxy

It is worth noting that mitmproxy also allows you to intercept HTTPS traffic by issuing a self-signed certificate to the client. A good example of how to set up interception and modification of traffic is possible.

Dsniff

Well, this utility is generally one of the first that should come to mind as soon as you hear
"MITM attack". The tool is quite old, but it continues to be actively updated, which is good news. It makes no sense to talk in detail about its capabilities, over the fourteen years of its existence, it has been covered more than once on the network. For example, in a tutorial like this:

well, or instructions from our website:

Lastly ..

As usual, we have not considered all the utilities, but only the most popular ones; there are still many little-known projects that we may talk about sometime. As you can see, there is no shortage of tools for conducting MITM attacks, and, which happens not so often, one of the coolest tools is implemented for Windows. There is nothing to say about nix systems - a whole variety. So I think you can always find the right tool to hijack
alien credentials. Oops, that is, for testing.

Designating a situation when an attacker is able to read and modify at will the messages exchanged by correspondents, and none of the latter can guess about his presence in the channel.

Wikimedia Foundation. 2010.

See what "Man in the middle (attack)" is in other dictionaries:

Attack "man in the middle", MITM attack (English Man in the middle) is a term in cryptography, denoting a situation when a cryptanalyst (attacker) is able to read and modify at will the messages exchanged ... ... Wikipedia

- ... Wikipedia

Cryptanalysis (from the Greek κρυπτός hidden and analysis) is the science of methods of obtaining the initial value of encrypted information without having access to the secret information (key) necessary for this. In most cases, this means ... ... Wikipedia

Hacker attack in the narrow sense of the word nowadays is understood as "Attempt on the security system", and tends more towards the meaning of the following term "Cracker attack". This happened due to the distortion of the meaning of the word "hacker" ... Wikipedia

- (from other Greek κρυptός hidden and analysis) the science of methods of decrypting encrypted information without a key intended for such decryption. The term was coined by the American cryptographer William F. Friedman in 1920. Informally ... ... Wikipedia

Man-in-the-middle attack is a generic name for various techniques aimed at gaining access to traffic as an intermediary. Due to the wide variety of these techniques, it is problematic to implement a single tool for detecting these attacks that would work for all possible situations. For example, in a man-in-the-middle attack on a local network, ARP spoofing (poisoning) is usually used. And many man-in-the-middle attack detection tools watch for changes in Ethernet / address pairs or report suspicious ARP activity by passively monitoring ARP requests / responses. But if this attack is used on a maliciously configured proxy server, VPN, or in other cases where ARP poisoning is not used, then such tools are helpless.

The purpose of this section is to look at some of the techniques for detecting man-in-the-middle attacks, as well as some of the tools designed to determine if a MitM attack is taking place against you. Due to the variety of methods and implementation scenarios, it is impossible to guarantee 100% detection.

1. Traffic modification detection

As already mentioned, ARP spoofing is not always used in man-in-the-middle attacks. Therefore, while ARP-level activity detection is the most popular detection method, traffic modification detection is a more general method. The mitmcanary program can help us with this.

The principle of the program is that it makes "control" requests and saves the received responses. After that, it repeats the same requests at certain intervals and compares the responses received. The program is intelligent enough and to avoid false positives it detects dynamic elements in responses and processes them correctly. As soon as the program detects traces of the activity of tools for MitM attacks, it reports this.

Examples of how some tools can "inherit":

MITMf, by default, changes all HTTPS URLs in HTML code to HTTP. Revealed by comparing HTTP content.
Zarp + MITMProxy, MITMProxy has functionality that allows you to clear HTTP compression, this is used for the transparency of transmitted traffic, this bundle is detected by the disappearance of previously present compression
Responder, detected by sudden changes in the conversion of mDNS responses: unexpected response; the answer is internal, but external is expected; response is different from expected IP

MITMCanary vs MITMf:

MITMCanary vs Responder:

MITMCanary vs Zarp + MITMProxy:

Sudo pip install Cython sudo apt-get install python-kivy python-dbus sudo pip install plyer uuid urlopen analysis request simplejson datetime git clone https://github.com/CylanceSPEAR/mitmcanary.git cd mitmcanary /

As already mentioned, mitmcanary should start with control requests. To do this, go to the directory

Cd service /

And run the file setup_test_persistence.py:

Python2 setup_test_persistence.py

This will take some time - wait until the end. No error messages should be displayed (if so, then you are missing some dependencies).

Something like this will be output:

[email protected]: ~ / bin / mitmcanary / service $ python2 setup_test_persistence.py Older configuration version detected (0 instead of 14) Upgrading configuration in progress. Purge log fired. Analysing ... Purge finished! Record log in /home/mial/.kivy/logs/kivy_16-11-01_0.txt v1.9.1 v2.7.12 + (default, Sep 1 2016, 20:27:38)

After the end of this process, in the same directory execute (this will start the background process):

Python2 main.py

After that open a new terminal window and change to the horse directory with mitmcanary. I have this directory bin / mitmcanary /, so I enter

Cd bin / mitmcanary /

and execute there:

Python2 main.py

The first window displays something like:

[email protected]: ~ / bin / mitmcanary / service $ python2 main.py Record log in /home/mial/.kivy/logs/kivy_16-11-01_1.txt v1.9.1 v2.7.12 + (default, Sep 1 2016, 20:27 : 38) using for socket listening for Tuio on 127.0.0.1:3000 Sleeping for 60 seconds Sleeping for 60 seconds Sleeping for 60 seconds Sleeping for 60 seconds Sleeping for 60 seconds Sleeping for 60 seconds

Those. the program makes control requests once a minute and looks for signs of a man-in-the-middle attack in them.

In the second window there is also output + a dark window opens, the authors of the program call this window a "graphical interface":

You can wait a while, surf the Internet to make sure that the program does not give any false warnings.

Let's try the classic Ettercap program.

I am running a regular MitM attack with ARP spoofing. The mitmcanary does not react to etching itself. The mitmcanary tool generates traffic itself, that is, no user action is required. After some time, a single warning appears, which is not confirmed during subsequent next checks. But a similar warning appears after a few minutes. Without additional analysis, I find it difficult to say whether this is an example of a false positive - it is very similar to that. It is possible that this warning is caused by a communication disruption caused by the need for traffic to pass additional routes, or by the peculiarities of my poor-quality Internet connection.

Since the result is not obvious (more "no" than "yes"), let's try the Bettercap program, which has a variety of modules. I have no doubt that when using various Ettercap plugins and / or additional programs to expand functionality, we would also "light up" for mitmcanary.

For the purity of the experiment, I restart the equipment, run mitmcanary on the attacked machine and Bettercap on the attacking one. At the same time, it is not necessary to make control requests again on the attacked machine - they are saved in a file inside the directory with the program. Those. just start the service and the GUI.

And in the attacking machine, we will run Bettercap with the parsers enabled:

Sudo bettercap -X

Individual warnings appear, which also look more like false positives.

But running a command like this:

Sudo bettercap -X --proxy

On the attacked machine, it generates a large number of warnings about a possible man-in-the-middle attack:

So, the more functional a man-in-the-middle attack tool, the more traces it leaves in traffic. For the practical use of mitmcanary, the following conditions must be met:

make initial requests on a trusted network when you are sure that there is no intermediary in the transmission of traffic;
edit the resources to which verification requests are made, since a professional attacker can add default resources to exceptions, which will make him invisible to this tool.

2. Revealing ARP spoofing (ARP cache poisoning)

Very often, a man-in-the-middle attack on a LAN begins with ARP poisoning. That is why many tools designed to detect MitM attacks are based on a mechanism for tracking changes in the ARP cache, in which the correspondence between Ethernet (MAC addresses) and IP addresses is assigned.

Examples of such programs include arpwatch, arpalert, and a large number of new programs. ArpON not only monitors ARP cache changes, but also protects it from them.

As an example, let's run arpwatch in debug mode, without forking in the background and sending messages by mail. Instead, messages are sent to stderr (standard error output).

Sudo / usr / sbin / arpwatch -d

Launch Ettercap on the attacking machine and start ARP spoofing. On the attacked machine, we observe:

The arpwatch program will help you quickly find out about new connected devices to your local network, as well as about changes in the ARP cache.

Another tool for detecting ARP spoofing in real time is a plugin from Ettercap itself called arp_cop... Launch Ettercap on the attacked machine as follows:

Sudo ettercap -TQP arp_cop ///

And on the attacker, let's start ARP-etching. The attacked machine immediately starts displaying warnings:

3. DNS spoofing detection

DNS spoofing indicates that there is an intermediary between you and your destination that can modify your traffic. How can you tell if DNS records have been spoofed? The easiest way to do this is to compare with the responses of a trusted nameserver. But the records in the response sent to your request can also be spoofed ...

Those. you need to check either through an encrypted channel (for example, through Tor), or use non-standard settings (another port, TCP instead of UDP). This is roughly what XiaoxiaoPu's sans program is for (at least that's what I understand). Using this program, I managed to redirect DNS requests through Tor and through non-standard settings to my DNS server. But I still could not get her to show me messages about spoofing DNS responses. And without this, the meaning of the program is lost.

I could not find more worthy alternatives.

In principle, given that DNS spoofers usually monitor only port 53, and only the UDP protocol, then even manually it is enough just to check the fact of DNS spoofing, although this requires your own DNS server with a non-standard configuration. For example, on the attacking machine, I created the file dns.conf with the following content:

Local mi-al.ru

Those. when requesting a DNS record for the mi-al.ru site, instead of the real IP, the IP of the attacker's machine will be sent.

I run it on the attacking machine:

Sudo bettercap --dns dns.conf

And on the attacked one I do two checks:

Dig mi-al.ru # and dig mi-al.ru -p 4560 @ 185.117.153.79

Results:

[email protected]: ~ $ dig mi-al.ru;<<>> DiG 9.10.3-P4-Debian<<>> mi-al.ru ;; global options: + cmd ;; Got answer: ;; - >> HEADER<<- opcode: QUERY, status: NOERROR, id: 51993 ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;mi-al.ru. IN A ;; ANSWER SECTION: mi-al.ru. 86400 IN A 192.168.1.48 ;; Query time: 2 msec ;; SERVER: 8.8.8.8#53(8.8.8.8) ;; WHEN: Wed Nov 02 09:25:20 MSK 2016 ;; MSG SIZE rcvd: 42 [email protected]: ~ $ dig mi-al.ru -p 4560 @ 185.117.153.79;<<>> DiG 9.10.3-P4-Debian<<>> mi-al.ru -p 4560 @ 185.117.153.79 ;; global options: + cmd ;; Got answer: ;; - >> HEADER<<- opcode: QUERY, status: NOERROR, id: 401 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 512 ;; QUESTION SECTION: ;mi-al.ru. IN A ;; ANSWER SECTION: mi-al.ru. 3799 IN A 185.26.122.50 ;; Query time: 304 msec ;; SERVER: 185.117.153.79#4560(185.117.153.79) ;; WHEN: Wed Nov 02 09:25:27 MSK 2016 ;; MSG SIZE rcvd: 53

It can be seen that the local IP 192.168.1.48 was sent for a "regular" DNS query, and the correct server IP is sent when querying the DNS on an atypical port.

If the server were configured to work with TCP (not UDP), then the command would look like this:

Dig mi-al.ru -p 4560 + tcp @ 185.117.153.79

There is clearly a lack of a tool that would itself track DNS responses in traffic, recheck them against an alternative source and raise an alarm in case of spoofing.

To avoid setting up your own remote DNS, you can query the nameserver over Tor. Since all Tor traffic is encrypted, the DNS responses obtained in this way are too tough for an intermediary. If Tor is not already installed, then install it.

Sudo apt-get install tor

Sudo pacman -S tor

Start the service:

Sudo systemctl start tor

If you need it, add this service to startup:

Sudo systemctl enable tor

Open the file / etc / tor / torrc and add the following lines there:

DNSPort 530 AutomapHostsOnResolve 1 AutomapHostsSuffixes .exit, .onion

Pay attention to the number 530. This is the port number, instead of 530 you can specify any other (unoccupied) port. The main thing is to remember it.

We do checks again:

Dig mi-al.ru # and dig mi-al.ru -p 530 @localhost

Now we specify as the server localhost, and write the port number that you specified in the / etc / tor / torrc settings.

As you can see from the following screenshot, a DNS spoofing attack is being carried out against the machine on which the check was made:

4. Searching for network interfaces in promiscuous mode

If your local network has (and especially if it suddenly appeared) equipment in an illegible mode, this is very suspicious, although it does not unequivocally indicate a man-in-the-middle attack.

In this mode, the network card allows all packets to be received regardless of who they are addressed to.

In the normal state, the Ethernet interface uses link layer packet filtering, and if the MAC address in the destination header of the received packet does not match the MAC address of the current network interface and is not broadcast, then the packet is dropped. In promiscuous mode, filtering on the network interface is disabled and all packets, including those not intended for the current host, are allowed into the system.

Most operating systems require administrator rights to enable promiscuous mode. Those. Promoting a NIC is a deliberate action that can be used for sniffing purposes.

To search for network interfaces in promiscuous mode, there is an Ettercap plugin called search_promisc.

An example of starting a plugin:

Sudo ettercap -TQP search_promisc ///

The plug-in is not completely reliable, there may be errors in determining the mode of the network interface.

Conclusion

Some man-in-the-middle attacks leave many traces, and some (like passively looking for credentials on a proxy) are impossible or nearly impossible to detect.

In which a cracker, having connected to a channel between counterparties, interferes with the transmission protocol, deleting or distorting information.

Attack principle

The attack usually starts with listening to the communication channel and ends with the cryptanalyst trying to replace the intercepted message, extract useful information from it, and redirect it to some external resource.

Suppose object A plans to convey some information to object B. Object C has knowledge about the structure and properties of the used data transfer method, as well as about the fact of the planned transfer of the actual information that C plans to intercept. To carry out an attack, C "appears" to object A as B, and to object B as A. Object A, mistakenly believing that it sends information to B, sends it to object C. Object C, having received information, and having performed some actions with it (for example having copied or modified for their own purposes) sends the data to the recipient proper - B; subject B, in turn, believes that the information was received directly from A.

An example of an attack

Injection of malicious code

A man-in-the-middle attack allows a cryptanalyst to inject his code into emails, SQL statements, and web pages (ie, allows SQL injection, HTML / script injection, or XSS attacks), and even modify user-uploaded binaries to to access a user account or change the behavior of a program downloaded by a user from the Internet.

Downgrade attack

The term "Downgrade Attack" refers to an attack in which a cryptanalyst forces the user to use less secure functions, protocols that are still supported for compatibility reasons. This type of attack can be carried out against the SSH, IPsec and PPTP protocols.

To protect against Downgrade Attack, unsafe protocols must be disabled on at least one side; just supporting and using secure protocols by default is not enough!

SSH V1 instead of SSH V2

An attacker can try to change the connection parameters between the server and the client when establishing a connection between them. According to a talk given at Blackhat Conference Europe 2003, a cryptanalyst can "force" a client to start an SSH1 session instead of SSH2 by changing the version number "1.99" for the SSH session to "1.51", which means using SSH V1. The SSH-1 protocol has vulnerabilities that can be exploited by a cryptanalyst.

IPsec

In such an attack scenario, the cryptanalyst misleads his victim into thinking that the IPsec session cannot start on the other end (server). This leads to the fact that messages will be forwarded explicitly, if the host machine is running in rollback mode.

PPTP

At the stage of negotiating PPTP session parameters, the attacker can force the victim to use the less secure PAP authentication, MSCHAP V1 (that is, "roll back" from MSCHAP V2 to version 1), or not use encryption at all.

The attacker can force his victim to repeat the stage of negotiating the PPTP session parameters (send a Terminate-Ack packet), steal the password from the existing tunnel and repeat the attack.

Public means of communication without protecting the reliability, confidentiality, availability and integrity of information

The most common means of communication for this group are social networks, public e-mail services and instant messaging systems. The owner of the resource that provides the communications service has full control over the information exchanged by the correspondents and, at his discretion, can easily carry out an attack at any time.

In contrast to the previous scenarios based on technical and technological aspects of communication means, in this case the attack is based on mental aspects, namely, the concept of ignoring information security requirements is rooted in the minds of users.

Will encryption save you?

Consider the case of a standard HTTP transaction. In this case, an attacker can quite easily split the original TCP connection into two new ones: one between himself and the client, the other between himself and the server. This is quite easy to do, since it is very rare that the connection between the client and the server is direct, and in most cases they are connected through a number of intermediate servers. An MITM attack can be carried out on any of these servers.

However, if the client and server communicate over HTTPS, a protocol that supports encryption, a man-in-the-middle attack can also be carried out. This type of connection uses TLS or SSL to encrypt requests, which seemingly makes the channel secure from sniffing and MITM attacks. An attacker can create two independent SSL sessions for each TCP connection. The client establishes an SSL connection with the attacker, who in turn creates a connection to the server. In such cases, the browser usually warns that the certificate is not signed by a trusted certification authority, but ordinary users of outdated browsers can easily bypass this warning. In addition, an attacker may have a certificate signed by a root CA (for example, such certificates are sometimes used for DLP) and not generating alerts. In addition, there are a number of attacks against HTTPS. Thus, the HTTPS protocol cannot be considered secure against MITM attacks among ordinary users. [ ] There are a number of measures that prevent some of the MITM attacks on https sites, in particular, HSTS, which prohibits the use of http connections from sites, Certificate pinning and HTTP Public Key Pinning, which prohibit certificate spoofing.

MITM attack detection

To detect a man-in-the-middle attack, you need to analyze network traffic. For example, to detect an SSL attack, you should pay attention to the following parameters:

Server IP
DNS server
X.509 - server certificate
- Is the certificate self-signed?
- Is the certificate signed by a certification authority?
- Has the certificate been revoked?
- Has the certificate changed recently?
- Have other customers on the Internet received the same certificate?

MITM attack implementations

The listed programs can be used to carry out man-in-the-middle attacks, as well as to detect them and test the system for vulnerabilities.

Write a review on "Middleman Attack"

Literature

Excerpt from Mediator Attack

“Quartire, quartire, logement,” said the officer, looking down at the little man with a condescending and good-natured smile. - Les Francais sont de bons enfants. Que diable! Voyons! Ne nous fachons pas, mon vieux, [Apartments, apartments ... The French are good guys. Damn it, let's not quarrel, grandfather.] - he added, patting the frightened and silent Gerasim on the shoulder.
- A ca! Dites donc, on ne parle donc pas francais dans cette boutique? [Well, is it really true that no one here speaks French?] - he added, looking around and meeting Pierre's eyes. Pierre stepped back from the door.
The officer again turned to Gerasim. He demanded that Gerasim show him the rooms in the house.
“There’s no master — don’t understand… my yours…” said Gerasim, trying to make his words clearer by the fact that he spoke them in reverse.
The French officer, smiling, threw up his hands in front of Gerasim's nose, letting him feel that he did not understand him, and limping, went to the door at which Pierre was standing. Pierre wanted to move away in order to hide from him, but at that very time he saw Makar Alekseich leaning out from the opening door of the kitchen with a pistol in his hands. With the cunning of a madman, Makar Alekseich looked at the Frenchman and, raising his pistol, took aim.
- Aboard!!! The drunk shouted, pressing the trigger of the pistol. The French officer turned to shout, and at the same instant Pierre threw himself at the drunk. While Pierre grabbed and raised the pistol, Makar Alekseich finally hit the trigger with his finger, and a shot rang out, deafening and dousing everyone with gunpowder smoke. The Frenchman turned pale and rushed back to the door.
Having forgotten his intention not to reveal his knowledge of the French language, Pierre, having pulled out the pistol and thrown it, ran up to the officer and spoke to him in French.
"Vous n" etes pas blesse? [Are you hurt?] He said.
"Je crois que non," the officer replied, feeling himself, "mais je l" ai manque belle cette fois ci, "he added, pointing to the beating plaster in the wall." Quel est cet homme? [It seems not ... but this once it was close. Who is this man?] - the officer said with a stern glance at Pierre.
- Ah, je suis vraiment au desespoir de ce qui vient d "arriver, [Ah, I really am in despair of what happened,]" Pierre said quickly, completely forgetting his role. - C "est un fou, un malheureux qui ne savait pas ce qu "il faisait. [This is an unfortunate madman who did not know what he was doing.]
The officer went up to Makar Alekseich and grabbed him by the collar.
Makar Alekseich, letting open his lips, as if falling asleep, swayed, leaning against the wall.
“Brigand, tu me la payeras,” said the Frenchman, removing his hand.
- Nous autres nous sommes clements apres la victoire: mais nous ne pardonnons pas aux traitres, [Rogue, you will pay me for this. Our brother is merciful after the victory, but we do not forgive the traitors,] - he added with gloomy solemnity on his face and with a beautiful energetic gesture.
Pierre continued, in French, to persuade the officer not to recover from this drunken, insane man. The Frenchman listened in silence, without changing his gloomy look, and suddenly turned to Pierre with a smile. He looked at him in silence for a few seconds. His handsome face took on a tragically gentle expression, and he held out his hand.
- Vous m "avez sauve la vie! Vous etes Francais, [You saved my life. You are French,] - he said. For a Frenchman, this conclusion was beyond doubt. Only a Frenchman could do a great thing, and saving his life, Mr. Ramball" I capitaine du 13 me leger [Monsieur Rambal, captain of the 13th light regiment] - was, without a doubt, the greatest deed.
But no matter how undoubted this conclusion and the officer's conviction based on it, Pierre saw fit to disappoint him.
- Je suis Russe, [I am Russian,] - Pierre said quickly.
“Ti tee tee, a d" autres, [tell this to others,] - said the Frenchman, waving his finger in front of his nose and smiling. - Tout a l "heure vous allez me conter tout ca," he said. - Charme de rencontrer un compatriote. Eh bien! qu "allons nous faire de cet homme? [Now you’ll tell me all this. It’s very nice to meet a compatriot. Well, what can we do with this man?" Pierre was not a Frenchman, having received this highest name in the world, he could not renounce it, the expression on the face and tone of the French officer spoke. a drunken, insane man stole a loaded pistol, which they did not manage to take from him, and asked to leave his act unpunished.
The Frenchman put out his chest and made a royal hand gesture.
- Vous m "avez sauve la vie. Vous etes Francais. Vous me demandez sa grace? Je vous l" accorde. Qu "on emmene cet homme, [You saved my life. You are French. Do you want me to forgive him? I forgive him. Take this man away," the French officer said quickly and energetically, taking by the arm what he had done to save his life into the French Pierre, and went with him to the house.
The soldiers who were in the yard, hearing the shot, entered the entrance, asking what had happened and expressing their readiness to punish the guilty; but the officer sternly stopped them.
- On vous demandera quand on aura besoin de vous, [When necessary, you will be called,] - he said. The soldiers left. The orderly, who had in the meantime been in the kitchen, went up to the officer.
“Capitaine, ils ont de la soupe et du gigot de mouton dans la cuisine,” he said. - Faut il vous l "apporter? [The captain has soup and roast lamb in the kitchen. Would you like me to bring it?]
- Oui, et le vin, [Yes, and wine,] said the captain.

The French officer entered the house with Pierre. Pierre considered it his duty to reassure the captain that he was not French, and wanted to leave, but the French officer did not want to hear about it. He was so courteous, kind, good-natured and truly grateful for saving his life that Pierre did not have the heart to refuse him and sat down with him in the hall, in the first room they entered. In response to Pierre's assertion that he was not French, the captain, obviously not understanding how it was possible to refuse such a flattering title, shrugged his shoulders and said that if he certainly wanted to be known as a Russian, then let it be so, but that he, despite then, all the same forever associated with him a feeling of gratitude for saving a life.
If this man had been gifted in any way with the ability to understand the feelings of others and had guessed about Pierre's feelings, Pierre would probably have left him; but this man's animated impermeability to everything that was not himself won Pierre.
- Francais ou prince russe incognito, [French or Russian incognito prince,] - said the Frenchman, looking at Pierre's dirty, but thin linen and the ring on his hand. - Je vous dois la vie je vous offre mon amitie. Un Francais n "oublie jamais ni une insulte ni un service. Je vous offre mon amitie. Je ne vous dis que ca. [I owe you my life, and I offer you friendship. The French never forgets an insult or a favor. I offer you my friendship. I say nothing more.]
There was so much good nature and nobility (in the French sense) in the sounds of the voice, in the expression on the face, in the gestures of this officer that Pierre, responding with an unconscious smile to the smile of the Frenchman, shook his outstretched hand.
- Capitaine Ramball du treizieme leger, decore pour l "affaire du Sept, [Captain Rambal, Thirteenth Light Regiment, Knight of the Legion of Honor for the Seventh September cause,]" he introduced himself with a smug, irrepressible smile that curled his lips under his mustache. - Voudrez vous bien me dire a present, a qui "j" ai l "honneur de parler aussi agreablement au lieu de rester al" ambulance avec la balle de ce fou dans le corps. [Would you be so kind to tell me now who I am with I have the honor to talk so nicely, instead of being at the dressing station with this madman's bullet in the body?]
Pierre replied that he could not say his name, and, blushing, began, trying to invent a name, to talk about the reasons why he could not say it, but the Frenchman hastily interrupted him.
“De grace,” he said. - Je comprends vos raisons, vous etes officier ... officier superieur, peut etre. Vous avez porte les armes contre nous. Ce n "est pas mon affaire. Je vous dois la vie. Cela me suffit. Je suis tout a vous. Vous etes gentilhomme? [Complete, please. I understand you, you are an officer ... headquarters officer, maybe. You served against us It's none of my business. I owe you my life. That's enough for me, and I'm all yours. Are you a nobleman?] "He added with a tinge of question. Pierre bowed his head." Votre nom de bapteme, s "il vous plait? Je ne demande pas davantage. Monsieur Pierre, dites vous ... Parfait. C "est tout ce que je desire savoir. [Your name? I don't ask any more. Mister Pierre, did you say? Fine. That's all I need.]
When the fried lamb, scrambled eggs, samovar, vodka and wine from the Russian cellar, which the French had brought with them, were brought, Rambal asked Pierre to take part in this dinner and immediately, greedily and quickly, like a healthy and hungry man, began to eat, quickly chewing with his strong teeth, constantly smacking his lips and saying excellent, exquis! [wonderful, wonderful!] His face was flushed and covered with sweat. Pierre was hungry and took part in the dinner with pleasure. Morel, the orderly, brought a pot of warm water and placed a bottle of red wine in it. In addition, he brought a bottle of kvass, which he took in the kitchen for testing. This drink was already known to the French and got its name. They called the kvass limonade de cochon (pork lemonade), and Morel praised this limonade de cochon that he found in the kitchen. But since the captain had wine obtained during the passage through Moscow, he provided kvass to Morel and took up a bottle of Bordeaux. He wrapped the bottle up to the neck in a napkin and poured himself and Pierre some wine. Satisfied hunger and wine revived the captain even more, and he talked incessantly during dinner.
- Oui, mon cher monsieur Pierre, je vous dois une fiere chandelle de m "avoir sauve ... de cet enrage ... J" en ai assez, voyez vous, de balles dans le corps. En voila une (on pointed to the side) a Wagram et de deux a Smolensk, - he showed the scar that was on his cheek. - Et cette jambe, comme vous voyez, qui ne veut pas marcher. C "est a la grande bataille du 7 a la Moskowa que j" ai recu ca. Sacre dieu, c "etait beau. Il fallait voir ca, c" etait un deluge de feu. Vous nous avez taille une rude besogne; vous pouvez vous en vanter, nom d "un petit bonhomme. Et, ma parole, malgre l" atoux que j "y ai gagne, je serais pret a recommencer. Je plains ceux qui n" ont pas vu ca. [Yes, my dear Monsieur Pierre, I am obliged to light a good candle for you for saving me from this madman. You see, I've had enough of those bullets that I have in my body. Here is one near Wagram, another near Smolensk. And this leg, you see, does not want to move. This is at the big battle of the 7th near Moscow. O! it was wonderful! You should have seen it was a deluge of fire. You have given us a difficult job, you can boast. And by God, despite this trump card (he pointed to the cross), I would be ready to start all over again. I pity those who did not see it.]
- J "y ai ete, [I was there,] - said Pierre.
- Bah, vraiment! Eh bien, tant mieux, said the Frenchman. - Vous etes de fiers ennemis, tout de meme. La grande redoute a ete tenace, nom d "une pipe. Et vous nous l" avez fait cranement payer. J "y suis alle trois fois, tel que vous me voyez. Trois fois nous etions sur les canons et trois fois on nous a culbute et comme des capucins de cartes. Oh !! c" etait beau, monsieur Pierre. Vos grenadiers ont ete superbes, tonnerre de Dieu. Je les ai vu six fois de suite serrer les rangs, et marcher comme a une revue. Les beaux hommes! Notre roi de Naples, qui s "y connait a crie: bravo! Ah, ah! Soldat comme nous autres!" He said, smiling, eating a moment's silence. "Tant mieux, tant mieux, monsieur Pierre. Terribles en bataille ... galants ... - he winked with a smile, - avec les belles, voila les Francais, monsieur Pierre, n "est ce pas? [Bah, really? All the better. You are dashing enemies, I must confess. The big redoubt held up well, damn it. And you made us pay dearly. I was there three times, as you can see. Three times we were on cannons, three times we were knocked over like card soldiers. Your grenadiers were great, by God. I saw how their ranks closed up six times and how they went exactly to the parade. Wonderful people! Our Neapolitan king, who ate the dog in these matters, shouted to them: bravo! - Ha, ha, so you are our brother soldier! “So much the better, so much the better, Monsieur Pierre. Terrible in battles, kind with beauties, here are the French, Monsieur Pierre. Is not it?]
To such an extent the captain was naively and good-naturedly cheerful, and wholehearted, and pleased with himself that Pierre almost winked himself, looking at him merrily. Probably the word "galant" made the captain think about the situation in Moscow.