Source: cve@mitre.org
Unspecified vulnerability in the bzip2 decompression algorithm in nsis/bzlib_private.h in ClamAV before 0.92 has unknown impact and remote attack vectors.
ClamAV versions prior to 0.92 are vulnerable to a critical flaw in their bzip2 decompression algorithm, potentially allowing for remote code execution (RCE). This vulnerability, stemming from an unspecified issue in the handling of compressed data, could be exploited to compromise systems processing malicious files, leading to system takeover and data breaches.
Step 1: Payload Delivery: An attacker crafts a malicious file containing a bzip2 compressed section designed to exploit the vulnerability. This file could be an archive (e.g., ZIP, RAR), an email attachment, or any file type scanned by ClamAV.
Step 2: File Ingestion: The victim's system receives the malicious file, which is then processed by ClamAV's scanning engine.
Step 3: Decompression Trigger: ClamAV's bzip2 decompression algorithm within bzlib_private.h is invoked to decompress the malicious bzip2 data.
Step 4: Vulnerability Exploitation: The crafted bzip2 data triggers the unspecified vulnerability within the decompression process. This could lead to a buffer overflow, memory corruption, or other exploitable condition.
Step 5: Code Execution/System Compromise: Depending on the nature of the vulnerability, the attacker can potentially achieve remote code execution (RCE), allowing them to execute arbitrary code on the victim's system. This could lead to complete system compromise, data theft, or denial of service.
The vulnerability lies within the nsis/bzlib_private.h file, specifically in the bzip2 decompression algorithm used by ClamAV. The description indicates an unspecified flaw, which suggests a potential for various issues, including but not limited to integer overflows, buffer overflows, or incorrect handling of compressed data structures. The lack of specific details makes definitive root-cause analysis difficult without reverse engineering or access to the original vulnerability report. However, the impact is likely related to the way ClamAV processes bzip2 compressed files, potentially allowing an attacker to craft a malicious file that, when scanned, triggers a memory corruption or other exploitable condition. The vulnerability could be triggered by any file scanned by ClamAV that contains a bzip2 compressed section, such as archives, emails, or other file formats.
Due to the age of the vulnerability and the potential for RCE, it is likely that various threat actors, including both state-sponsored and financially motivated groups, could have developed or adapted exploits. The vulnerability could be leveraged in targeted attacks or as part of a broader campaign. The lack of specific details in the CVE makes it difficult to attribute it to a specific APT group. This CVE is not listed in the CISA KEV catalog.
Monitor ClamAV logs for unusual activity, such as errors during decompression or unexpected resource consumption.
Analyze network traffic for suspicious file transfers or connections associated with ClamAV scans.
Implement file integrity monitoring to detect changes to ClamAV binaries or configuration files.
Use a host-based intrusion detection system (HIDS) to monitor for suspicious processes or system calls related to ClamAV.
Examine memory dumps or core files generated during crashes for evidence of memory corruption or other exploitation artifacts.
Upgrade ClamAV to version 0.92 or later to patch the vulnerability.
Implement a robust patch management process to ensure timely updates to all software.
Restrict the types of files that ClamAV scans, if possible, to reduce the attack surface.
Regularly review and update ClamAV's configuration to minimize the risk of exploitation.
Implement a defense-in-depth strategy, including firewalls, intrusion detection systems, and endpoint protection, to mitigate the impact of a successful exploit.