Remcos

Remcos is a RAT type malware that attackers use to perform actions on infected machines remotely. This malware is extremely actively caped up to date with updates coming out almost every single month.

Type
Trojan
Origin
ex-USSR territory
First seen
1 June, 2016
Last seen
23 October, 2021
Global rank
7
Week rank
9
Month rank
9
IOCs
8548

What is Remcos trojan?

Remcos is a remote access trojan – a malware used to take remote control over infected PCs. It has been operational since 2016 when it first became available for sale in the underground hacker communities on the dark web.

Remcos RAT has been receiving substantial updates throughout its lifetime. In fact, this malware is being maintained extremely actively, with new releases coming out almost every month. In April 2019, the malware was available for purchase for as little as just over 60 dollars up to over 400 dollars depending on the selected package.

General description of Remcos trojan

This trojan is created and sold to clients by a “business” called Breaking Security. Although Breaking Security promises that the program is only available to those who intend to use it for legal purposes, in reality, Remcos RAT gives clients all necessary features to launch potentially destructive attacks. The malware can be purchased with different cryptocurrencies. The program can remotely control PCs with any Windows OS, including XP and newer. It can also capture screenshots, record keystrokes on infected machines, and send the collected information to host servers.

What’s more, it comes equipped with a crypto program that enables the malware to stay hidden from antivirus software. In fact, Breaking Security has released a video on its YouTube channel which demonstrates the analysis of how multiple antiviruses fail to detect the presence of Remcos. In addition, Breaking Security provides attackers with a keylogger that can be used to remotely record keystrokes of the victim, a mass mailer program that can be used to carry out distribution campaigns, and a DynDNS service with a client-server connection. With all additional services combined, purchasers gain all they need to create their own functioning botnets.

The company responsible for selling Remcos RAT to the criminals is registered in Germany. Germany is the only country out of all European Union members that do not allow looking up company details online. Therefore founders of Breaking Security are still not identified. The website itself does not provide any information about the company or the team behind Remcos. The domain name of the website itself is hosted on Cloudflare, and all information related to it is protected by the privacy policy of the hoster organization. Clearly, the people behind Breaking Security have taken a lot of effort to stay anonymous.

Remcos malware analysis

Remcos RAT execution and analysis can be watched in-depth in a video recorded in the ANY.RUN malware hunting service.

process graph of the Remcos execution Figure 1: Displays the lifecycle of Remcos as presented by a visual graph generated by ANY.RUN

text report 0f the Remcos trojan analysis Figure 2: A customizable text report generated by ANY.RUN is a feature specifically developed to simplify the sharing of research results.

Remcos trojan execution process

Remcos trojan can be delivered in different forms. Based on RAT's analysis, it can be spread as an executable file with the name that should convince users to open it, or it pretends to be a Microsoft Word file that exploits vulnerabilities to download and execute the main payload, obfuscate the server component. In our simulation, after Remcos made its way to infect the device and begin the execution process, it started VBS script execution. Script ran command line and proceeded to drop an executable file from it. This file was the main payload, and it carried out the main malicious activities – stealing information, changing the autorun value in the registry, and connecting to the C2 server.

remcos execution process tree Figure 3: Execution processes of Remcos as displayed by the ANY.RUN malware analysis service

Distribution of Remcos

Although being distributed using multiple methods, being provided in a bundle with mass mailer software, the analysis proves that Remcos RAT usually gets into victims’ machines through malicious attachments in spam email campaigns. The attackers normally use phishing techniques to try and trick users into downloading file attachments, commonly – contaminated Microsoft Office files. Once downloaded, the files would prompt the users to activate the macros required for the execution of Ramcos to start.

Attackers who utilize this trojan are known to target specific organizations and sometimes go a long way to craft custom phishing emails designed to fool their victims. Corporations that are known to become targets of Remcos attacks include news agencies and businesses energy industry-related businesses.

If the victim does enable the macros, they reconstruct a small executable file which is then dropped to a pre-specified location and launched from there. This file then proceeds to download the main payload, which is Remcos itself, from a control server and then begin the execution process. Even though the location can vary from sample to sample, it usually includes one of the following locations, typical for malware creators: %APPDATA% and %TEMP%.

How to detect Remcos using ANY.RUN?

Since Remcos trojan creates log files without encryption, cybersecurity specialists can analyze it. Open either the "Files" tab in the lower part of the task's window or click on the process and then on the "More Info" button in the appeared window. After that, all you need to do is just click on the logs.dat file. If you see strings like on the illustration below, you can be sure it Remcos.

remcos log file Figure 4: Remcos log file

Conclusion

Remcos RAT is a dangerous trojan available to attackers for a relatively low price. Despite its accessibility, it comes equipped with enough robust features to allow attackers to set up their own effective botnets. What's more, it is modernized with updates released nearly every month by the owner company. Accessibility and powerful feature set helped to make Ramcos into a powerful and dangerous trojan.

Thankfully, malware hunting services such as ANY.RUN gives professionals an equally robust feature set to research threats like Ramcos and respond with effective countermeasures.

IOCs

IP addresses
104.22.49.74
3.140.223.7
206.81.28.165
3.22.30.40
3.134.125.175
3.13.191.225
3.134.39.220
13.59.15.185
13.59.15.185
3.142.129.56
3.22.53.161
3.138.45.170
52.14.18.129
3.131.207.170
3.129.187.220
3.133.207.110
3.14.182.203
3.141.177.1
3.17.7.232
3.22.15.135
Hashes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6.tcp.ngrok.io
isns.net
4.tpc.ngrok.io
87ea-34-121-202-111.ngrok.io
1db9-185-159-157-19.ngrok.io
537a-41-143-187-7.ngrok.io
f0ed-2a10-8006-18e0-0-24c3-abef-18b9-7871.ngrok.io
7d67f862b60c.ngrok.io
cc8ef76b.ngrok.io
60abf116c991.ngrok.io
b3215b552b30.ngrok.io
531d77da8d8e.ngrok.io
ee9e7af221ee.ngrok.io
a0e866a420d7.ngrok.io
0ff5435b0408.ngrok.io
fc648a51db86.ngrok.io
52cdd43ca1f4.ngrok.io
8ef628b4602c.ngrok.io
64fa466e7f1b.ngrok.io
e644e4bcb557.ngrok.io

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