Remcos

Remcos is a RAT type malware which means that attackers use it 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
19 January, 2021
Global rank
9
Week rank
7
Month rank
8
IOCs
5480

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 through 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 is able to remotely control PCs with any Windows OS including XP and newer. It can also capture screenshots and record keystrokes on infected machines.

What’s more, it comes equipped with a cryptor 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 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 all additional services connected, 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 which do not allow to look 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 about 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 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. For instance, 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. In our simulation, after Remcos made its way to infect the device and begin the execution process, it started VBS script execution. Script run 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, 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 macros which are 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. 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%. This file then proceeds to download the main payload, which is Remcos itself, from a control server and then being the execution process.

How to detect Remcos using ANY.RUN?

Since Remcos trojan creates log files without encryption analysts can take a look at it. Open either "Files" tab in the lower part of the task's window or click on the process and then on the button "More Info" 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 inexpensive 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 that are being 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
193.161.193.99
194.5.97.135
185.244.26.241
179.43.166.30
72.11.157.241
3.138.180.119
79.134.225.23
185.19.85.159
3.131.147.49
3.136.65.236
3.133.207.110
181.57.204.131
79.134.225.19
23.105.131.146
79.134.225.106
3.138.45.170
185.140.53.234
91.193.75.45
13.59.15.185
216.38.7.225
Hashes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servr.killwhenabuse1.xyz
harold.jetos.com
2.tcp.ngrok.io
severdops.ddns.net
isns.net
4.tcp.ngrok.io
isrealpicker.duckdns.org
arketype.giize.com
srvr2.callofdutyserver.pw
wedsazxcvfghyuiokjhbnvfcdsaweyplmhbvrtud.ydns.eu
teamsf.teamsf.team
mxtopsz.duckdns.org
nmaxom.duckdns.org
web.royaltygist.com
web.holinessinchrist.com
web.christexousia.org
web.apple-bytes.com
mike101.duckdns.org
shellgang.dynu.net
Toolz.mywire.org

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