Threat Report

WinRAR Directory Traversal & NTFS ADS Vulnerabilities (CVE-2025-6218 & CVE-2025-8088) Two high-severity vulnerabilities in WinRAR for Windows enable attackers to write files outside intended extraction directories.

Threat Overview

Two critical vulnerabilities have been identified in WinRAR, a popular file archiver utility. These vulnerabilities, designated as CVE-2025-6218 and CVE-2025-8088, allow attackers to perform directory traversal attacks and exploit NTFS Alternate Data Streams (ADS) to achieve remote code execution and persistent access in enterprise environments.

CVE-2025-6218 involves traditional path traversal techniques, enabling attackers to write files outside the intended extraction directories. This can lead to various malicious activities, including dropping payloads into autorun locations or hiding them within ADS.

CVE-2025-8088 extends this attack by leveraging NTFS Alternate Data Streams (ADS). ADS allows data to be stored in a file without altering its size or content, making it an ideal vector for stealthy persistence. Attackers can use ADS to hide malicious payloads and execute them remotely.

These vulnerabilities affect WinRAR versions 7.11 and earlier. Users are strongly advised to update to the latest version, 7.13, which includes patches for these issues.

Detailed Analysis

The vulnerabilities in WinRAR pose a significant threat due to their potential for remote code execution and persistent access. Attackers can exploit these flaws with minimal user interaction, making them particularly dangerous in enterprise environments where users may frequently extract archived files.

CVE-2025-6218 allows attackers to traverse directories by manipulating the path of extracted files. This can be achieved through specially crafted archive files that include directory traversal sequences. When these archives are extracted, malicious files can be written to arbitrary locations on the system, such as startup folders or system directories.

CVE-2025-8088 builds upon this by utilizing NTFS Alternate Data Streams (ADS). ADS is a feature of the NTFS file system that allows multiple data streams to be associated with a single file. Attackers can embed malicious payloads within these streams, making them difficult to detect and remove.

The exploitation of these vulnerabilities requires minimal user interaction. Users need only extract an archive containing the malicious payload for the attack to succeed. This low barrier to entry makes these vulnerabilities particularly dangerous in environments where users frequently handle archived files.

Operational Security Measures

While WinRAR includes some operational security measures, such as digital signatures and integrity checks, these are not sufficient to protect against the identified vulnerabilities. The use of traditional path traversal techniques and NTFS ADS makes it challenging for standard security tools to detect and mitigate these attacks.

Additionally, the widespread use of WinRAR in enterprise environments increases the potential impact of these vulnerabilities. Organizations should prioritize patching and implementing additional security measures to protect against these threats.

Recommendations for Mitigation

Organizations can take several steps to mitigate the risks posed by these vulnerabilities:

• Immediate Patching: Update WinRAR to version 7.13 or later, which includes patches for CVE-2025-6218 and CVE-2025-8088.
• Proactive Hunting: Implement proactive hunting techniques to detect and respond to potential exploitation attempts. This can include monitoring for unusual file extraction activities and scanning for hidden ADS.
• User Education: Educate users about the risks associated with extracting files from untrusted sources. Encourage them to verify the integrity of archives before extraction and report any suspicious activity.
• Network Segmentation: Implement network segmentation to limit the lateral movement of attackers within the network. This can help contain potential breaches and prevent the spread of malicious payloads.
• Endpoint Protection: Deploy endpoint protection solutions that can detect and block malware associated with these vulnerabilities. Regularly update these solutions to ensure they are effective against the latest threats.
• Regular Backups: Maintain regular backups of critical data to ensure that it can be restored in the event of a ransomware attack or data loss. Backups should be stored offline or in a separate network segment to prevent them from being encrypted or deleted by malware.
• Incident Response Plan: Develop and maintain an incident response plan to ensure that the organization can respond quickly and effectively to security incidents. The plan should include steps for containing the threat, investigating the incident, and restoring affected systems.