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
18 February, 2020
Global rank
11
Week rank
9
Month rank
12
IOCs
1741

What is Remcos?

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

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, Remcos comes equipped with a cryptor program which enables the malware to stay hidden from antivirus software. In fact, Breaking Security has released a video on their 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 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 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 which 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 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 organization 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
192.169.69.25
79.134.225.108
181.58.155.117
173.254.223.106
216.38.7.245
79.134.225.77
107.174.253.192
79.134.225.74
185.140.53.153
216.38.8.168
185.244.31.114
185.244.30.53
185.244.30.16
79.134.225.80
193.161.193.99
185.244.30.4
66.154.98.108
185.244.30.9
79.134.225.105
79.134.225.116
Hashes
9e105b74500cfd24f56369e8824eb515cfe5681db60bc8db89bfaccec729e177
368906d50bd279e9576aaa3d6dea269515410a5f74cd93112767eb4bac310d1d
ff9397aed073819c5fe29bad83602ae599a86063b19d678d27c37866272060a4
d783cab5c5ae5cada441b48ab938855e5fb5a0f696f31f86d68479041cc991cf
8fd3a668fbd3331f4a850c9997692dbb6a9dd57581ae7aebfaedf6a153aaacdf
c5d6d56ded55fbd6c150ee3a0eb2e5671cae83106be2be4d70ce50aa50bab768
cf2f9f6763f9bdd32dc0ecd1d3857efbb250c4faa6ac6b449596be08c472c26f
b2da87fc7dcd126af8600921a971774ad280c02fdab9b7df015337dc2fca149d
7855088ace35fb7ca2d2ab24a17a06c0286861a389ecda8cc6710bd2a37212d9
9b9a39670c7bf766660509957d7fe703d4bd915f6ff380353f20184d3578d73c
fc96b2373284fdcb2ffb46f5bc581886c9a58bd8be1dbc56525feda5c0d11aa9
6ec5166388c73454a5cf3a9647de9d88312a2084e6888a6daef568622ccbae7c
3b6600cfbddd890712b0e35ea6fcde35391c05ae68032c85095be38cec3bdc09
c9c0180eba2a712f1aba1303b90cbf12c1117451ce13b68715931abc437b10cd
dfba5dcaf22fb3f61d71d241e2e30c288b67136d41df06beef007ccf2492e4b9
8de049c0163cb50c0093fc635e35e7b5e63e85b52e4a553ba8ae6d571039e89e
1b7fb360e41774b42e9aec3cdb16697216799c13c93d0bba9c95df14c587ccea
c37e19a4cbe15ba79ffbf2034035c24812e2fad6fd4ef01a33a2473abdf5ed1e
a4d6765ff194dc15f845e757ae7c6f6c3285e8139cd1c14b88441b0ddc15e23b
447ad6d39faabe5766f4b45aebc55745e79f0aa8b087c7fe810896507ce4e18d
Domains
thuocnam.tk
majul.com
m-onetrading-jp.com
krupskaya.com
isns.net
elx01.knas.systems
ponymaltadns.duckdns.org
aquaserver.duckdns.org
barcelonasevere.duckdns.org
keepservjfjf.duckdns.org
treintallegamos.duckdns.org
navidadserverazul.duckdns.org
ververdenuevo.duckdns.org
messielmejor.duckdns.org
jblllegolahora.duckdns.org
cartagenacity.duckdns.org
medellinmedell.duckdns.org
ibagueibague.duckdns.org
agrariobuenasuerte.duckdns.org
elsalvaje.duckdns.org

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