Fileless Revenge RAT Abuses Legitimate Tools to Hide Malicious Activity

Threat actors are distributing Revenge RAT malware, developed using legitimate tools like “smtp-validator” and “Email to SMS.”

When executed, the malware runs a malicious file and a legitimate tool, making it difficult for users to know there is malicious activity.

Moreover, threat actors have also created a setup.exe file that is executed and hidden before the execution of smtp-verifier.exe. In addition, several files are used in this Revenge RAT malware execution process.

Document
Live Account Takeover Attack Simulation

How do Hackers Bypass 2FA?

Live attack simulation Webinar demonstrates various ways in which account takeover can happen and practices to protect your websites and APIs against ATO attacks .

Revenge RAT Abuses Legitimate Tools

According to the reports shared with Cyber Security News, the malicious file “setup.exe” is used for generating additional malware by creating and running svchost.exe in the %appdata%Microsoft\Windows\Templates path with a hidden attribute.

Revenge RAT Malware flow (Source: AhnLab)

After this, the svchost.exe file is registered in the autorun registry by the setup.exe file with the value “Microsoft Corporation Security.” The svchost.exe file connects to the C2 server and downloads the HTML file, which is then decompressed.

The downloaded HTML file creates and runs the explorer.exe file in the %appdata%Microsoft\Windows\Templates path. There were 2 C2 servers mentioned as an alternate solution in case the first C2 server URL was blocked or when a new C2 was updated.

C2 with binary disguided (Source: AhnLab)

This new explorer.exe file creates another file with the name version.exe in the %appdata%Microsoft\Windows\ path and a .inf file in the %temp% path. This version.exe file is executed with an argument to cmstp.exe (CMSTP defense evasion). Finally, the Revenge RAT is run as fileless malware.

To further prevent disruption of the malware activity, version.exe is designed to run a PowerShell command that adds the files used by the Revenge RAT malware as an exception list in the Windows Defender.

ASEC provides detailed information on the malware, source code, file execution, etc.

Indicators of Compromise

File Detection

  • Trojan/Win.Generic.C4223332
  • Trojan/Win.Generic.C5583117
  • Dropper/Win.Generic.C5445718
  • Dropper/Win.Generic.R634030
  • Backdoor/Win.REVENGERAT.C5582863
  • Backdoor/Win.REVENGERAT.R634026

MD5

  • 42779ab18cf6367e7b91e621646237d1 (smtp-verifier.exe)
  • fb34fe9591ea3074f048feb5b515eb61 (Email To Sms V8.1.exe)
  • 6d5ad2adce366350200958c37f08a994 (setup.exe)
  • 914ec5019485543bb2ec8edcacd662a7 (setup.exe)
  • 5e24e97bbc8354e13ee3ab70da2f3af6 (svchost.exe)
  • 1242c41211464efab297bfa6c374223e (svchost.exe)
  • 438817d3938ae5758d94bf2022a44505 (explorer.exe)
  • 304e264473717fad8f7c6970212eaaa7 (version.exe)
  • d1af87e121d55230353cbad9b7024fae (Fileless RevengeRAT)
  • 6e22b450a765caa999ca984521b42242 (g1rfp0hb.inf)

C&C

  • qcpanel.hackcrack[.]io:9561

Stay updated on Cybersecurity news, Whitepapers, and Infographics. Follow us on LinkedIn & Twitter.

Eswar

Eswar is a Cyber security content editor with a passion for creating captivating and informative content. With years of experience under his belt in Cyber Security, he is covering Cyber Security News, technology and other news.

Recent Posts

Hackers Use ConnectWise SkyKick Credentials to Access Microsoft 365, Halting Cloud Backups

Attackers abused compromised ConnectWise Cloud Backup credentials to access Microsoft 365 customer environments, prompting ConnectWise…

1 day ago

Anthropic’s Claude AI Uncovers Origins of NSA-Provided Cryptographic Keys After 25 Years

Anthropic says an internal Claude research model reconstructed how the National Security Agency generated seeds…

1 day ago

Critical WordPress Flaws Allow Attackers to Execute Remote Code Without Authentication

Two WordPress Core vulnerabilities can be chained to execute remote code without authentication, according to…

1 day ago

OpenBSD Kernel Flaw Dating Back 37 Years Enables Local Privilege Escalation to Root

A newly disclosed OpenBSD kernel exploitation chain combines a shared memory accounting flaw with a…

1 day ago

GhostAction Hackers Hide Credential-Stealing Malware in Fake Font Files Across 94 GitHub Repositories

GhostAction attackers have expanded their GitHub credential theft campaign with a second stage that disguises…

1 day ago

SideCopy Hackers Target Indian Organizations With ReverseRAT Malware to Steal Data

Indian authorities have warned that SideCopy hackers are targeting Indian organizations, including academic institutions, with…

1 day ago