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Malware

Remcos RAT Malware Campaign Poses Persistent Threat to Windows Users

Cybersec Sentinel

• 2 min read
Remcos RAT Malware Campaign Poses Persistent Threat to Windows Users

Cybersec Sentinel
November 9, 2024

Threat Group: Various Cybercriminal Entities
Threat Type: Remote Access Trojan (RAT)
Exploited Vulnerabilities: Phishing emails, CVE-2017-0199, multi-layer obfuscation
Malware Used: Remcos RAT
Threat Score: Medium
Last Threat Observation: November 9, 2024

Overview

Remcos RAT, a commercial RAT initially marketed as a legitimate tool for remote Windows administration, has been active since 2016. Known for its versatility in enabling full remote control, Remcos is now frequently deployed in phishing campaigns targeting Windows systems. This malware can persist across reboots and incorporates advanced obfuscation and anti-debugging techniques to evade detection. Its primary functions include data theft, espionage, and unauthorized access to infected devices, where it can capture keystrokes, logins, financial details, and other confidential information.

Key Details

  • Delivery Method: Primarily spread through phishing emails with malicious attachments (e.g., Excel files and archive files containing executable scripts).
  • Target: Windows users and organizations across various sectors.
  • Impact:
    • Unauthorized system control and data theft.
    • Credential theft and espionage capabilities.
  • Persistence: Remcos maintains persistence on compromised systems, ensuring its presence even after a system reboot.
  • Obfuscation: Utilizes multi-layered encoding, such as JavaScript, VBScript, Base64, and PowerShell, to hinder detection.

Attack Vectors

The malware is delivered via phishing emails containing Excel documents exploiting CVE-2017-0199, a vulnerability that allows code execution upon opening the document. This initiates a sequence that downloads and executes Remcos RAT through a chain of files and scripts. The malware obfuscates its actions and evades detection using techniques such as API hooking, anti-debugging, and process hollowing to remain undetected within system processes.

Known Indicators of Compromise (IoCs)

File Hashes (MD5):

  • c5c9130e57bdec0048c45059f6f120f7
  • 4b08305b3f7ad50b68f949d85090c838
  • 7c8b45e6d2c2186cb9c3996410b6255c
  • 3775532b4be8a44cae7ca45b64197746
  • 10e19f80d967ab7d4a8ed10f674df5c5
  • 43794e837b00b4da73a178e2fb0d3edd
  • d1ad7ef34f7712fee812f4636c7749a4
  • 72079fd01da9b11fff30f4dd4c010319

File Hashes (SHA256):

  • 24a4ebf1de71f332f38de69baf2da3019a87d45129411ad4f7d3ea48f506119d
  • 4a670e3d4b8481ced88c74458fec448a0fe40064ab2b1b00a289ab504015e944
  • 9124d7696d2b94e7959933c3f7a8f68e61a5ce29cd5934a4d0379c2193b126be
  • d4d98fdbe306d61986bed62340744554e0a288c5a804ed5c924f66885cbf3514
  • f99757c98007da241258ae12ec0fd5083f0475a993ca6309811263aad17d4661
  • f9b744d0223efe3c01c94d526881a95523c2f5e457f03774dd1d661944e60852
  • 25d5929f0ef894bf532d5c21e03474a7f7db7cc0be168a2d618a40bb47de9643
  • d682eeadb7f5d9c10016bbe8ee8f8f16938d3f7c7b33b9703225efd552df6d5b

File Hashes (SHA1):

  • 31d2982daf825709aaa92b7bf096eed3bbc851f7
  • d476aab43cc8d7fc1320da5622754bf2e7e4c935
  • 4509b1e7d9b5cbd074295c457c1d7896f20b21c0
  • 965c1645f4df7fb3d08b29c0104782e14ec997e3

IP Addresses:

  • 107.173.4[.]16
  • 192.3.220[.]22

Mitigation and Prevention

  1. User Awareness: Conduct phishing prevention training to identify malicious emails and attachments.
  2. Email Filtering: Employ email filtering to detect and quarantine suspicious emails.
  3. Access Control: Limit administrative access to essential personnel and avoid public exposure of administrative portals.
  4. System Monitoring: Monitor for IoCs within logs and block IoCs at all security layers.
  5. Patch Management: Regularly update software and systems, with an emphasis on known vulnerabilities like CVE-2017-0199.
  6. Multi-Layer Protection: Use antivirus and anti-malware solutions with up-to-date signature definitions.
  7. Enhanced Password Policies: Enforce strong, unique passwords for all accounts and implement multi-factor authentication where possible.

Conclusion

Remcos RAT poses a serious risk to Windows users through its advanced data theft, unauthorized access, and persistence capabilities. To mitigate this threat, organizations should prioritize patch management, restrict administrative access, and reinforce user training. The multi-layered defenses provided by solutions such as antivirus, email filtering, and continuous monitoring are essential in combating the threat posed by Remcos RAT.

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