You are currently viewing WinRAR CVE-2025-8088: RomCom’s Doorway to Remote Code Execution

WinRAR CVE-2025-8088: RomCom’s Doorway to Remote Code Execution

Executive Summary

A critical vulnerability in WinRAR, identified as CVE-2025-8088, was exploited as a zero-day in targeted phishing attacks to deploy RomCom backdoors. This flaw, a directory traversal vulnerability, allows attackers to craft malicious archives that place executable files in Windows Startup folders, enabling remote code execution when the system is restarted. The vulnerability has been fixed in WinRAR v7.13, but active exploitation has been observed in the wild, making immediate patching essential.

Background on RomCom

RomCom is a Russia-aligned advanced persistent threat (APT) group known for cybercrime and espionage. They exploit zero-day vulnerabilities in WinRAR via spearphishing with malicious RAR attachments to deploy persistent malware. Their targets include defense, finance, and critical infrastructure sectors across Europe and Canada. RomCom uses sophisticated tactics such as custom RATs, decoy documents, and C2 communication for stealthy remote access and data theft.

Vulnerability Details

  • CVE-ID: CVE-2025-8088
  • CVSS Score: 8.4 (High severity)
  • EPSS Score: 2.97
  • Vulnerability Type: Directory Traversal / Path Traversal
  • Affected Software: WinRAR for Windows versions prior to 7.13
  • Patched in: WinRAR v7.13

The vulnerability arises due to improper validation of file paths in archive extraction. A specially crafted archive can place files in arbitrary locations, including sensitive system folders like the Windows Startup directory.

Infection Method

The RomCom attack leveraging CVE-2025-8088 follows this chain:

  1. Initial Access: Spear-phishing emails are sent to targeted victims containing malicious RAR attachments.
  2. Exploitation: Upon extraction with a vulnerable version of WinRAR, the malicious archive abuses directory traversal to drop executable payloads into the Windows Startup folder.
  3. Payload Execution: The malicious file runs automatically when the user next logs in.
  4. Backdoor Installation: The dropped file installs the RomCom backdoor, granting remote access to the attacker.
  5. Persistence: The startup placement ensures persistence until the malware is manually removed.

Malware Behavior and Capabilities

RomCom is a sophisticated backdoor with capabilities including:

  • Remote Command Execution: Full control over the compromised system.
  • Credential Theft: Harvests login data from browsers and other applications.
  • File Exfiltration: Targets sensitive documents for theft.
  • Lateral Movement: Expands access within the victim’s network.
  • Data Destruction & Ransomware Deployment: Known for double extortion attacks combining data theft with encryption.

Techniques Include (MITRE ATT&CK Mapping)

  • T1566.001 – Spearphishing Attachment: Initial delivery of malicious RAR files.
  • T1105 – Ingress Tool Transfer: Downloading additional malware payloads.
  • T1059.001 – Command and Scripting Interpreter: Use of PowerShell for execution.
  • T1053 – Scheduled Task/Job: Persistence mechanisms.
  • T1020 – Automated Exfiltration: Sending stolen data to attacker-controlled servers.
  • T1027 – Obfuscated Files or Information: Evading detection.

Visual: RomCom Attack Flow

[Targeted Spearphishing Email with Malicious RAR Attachment]
-> [User Opens Crafted Malicious RAR Archive]
-> [WinRAR Path Traversal Exploit via Alternate Data Streams]
-> [Malicious Files Deployed to System (DLL in Temp Folder, LNK in Startup Folder)]
-> [Persistence Established via Windows Startup Execution]
-> [Execution via COM Hijacking (Mythic Agent)] / [Execution of SnipBot Variant (Modified Executable)] / [Downloader Execution (RustyClaw/MeltingClaw)]
-> [Shellcode Execution and Payload Deployment]
-> [Command and Control (C2) Communication with Remote Servers]
-> [Additional Payload Delivery, Persistence, and Defense Evasion]

This flow highlights the attack stages where RomCom uses the CVE-2025-8088 WinRAR vulnerability—starting from highly targeted spearphishing emails with malicious RAR archives exploiting a path traversal flaw, enabling stealthy deployment of persistent backdoors and remote control malware in victim networks.

IOCs (Indicators of Compromise)

SHA-1 File Hash:

  • 1AEA26A2E2A7711F89D0 – ApbxHelper.exe (SnipBot)
  • AE687BEF963CB30A3788 – msedge.dll (Mythic agent)

Threat Actor Attribution

While formal attribution is pending for some observed activities, the exploitation of CVE-2025-8088 strongly aligns with sophisticated Russia-aligned Advanced Persistent Threat (APT) groups. The tactics suggest espionage and financially motivated operations targeting critical sectors such as finance, defense, manufacturing, and logistics across multiple regions

Researchers have identified these key groups actively exploiting CVE-2025-8088:

  • Storm-0978 (aka Tropical Scorpius, UNC2596): Known for credential theft and ransomware operations, targeting government and military organizations in Ukraine and Europe, leveraging sophisticated phishing and exploits.
  • UAT-5647: A multi-motivational Russian-speaking actor focused on espionage and data exfiltration, targeting Ukrainian and Polish entities using spearphishing and lateral movement.
  • UAC-0180: Engages in targeted attacks against defense enterprises, delivering multi-stage malware via phishing with ZIP archives and malicious LNK or HTA files, deploying tools written in various programming languages.

Mitigation Steps

  1. Patch Software: Update WinRAR to version 7.13 or later.
  2. Restrict Extraction Tools: Temporarily disable or replace vulnerable archiver tools in critical environments.
  3. Threat Hunting:
    • Monitor for file creation in C:\Users\<username>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup.
    • Check for unexpected network traffic to known RomCom C2 domains.
  4. IOC Monitoring: Use ESET and threat intelligence feeds to block known indicators.
  5. User Awareness: Train employees to avoid opening RAR attachments from unknown senders.

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