CVE-2008-6662 in AVG Anti-Virus
Summary
by MITRE
AVG Anti-Virus for Linux 7.5.51, and possibly earlier, allows remote attackers to cause a denial of service (segmentation fault) or possibly execute arbitrary code via a malformed UPX compressed file, which triggers memory corruption.
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Analysis
by VulDB Data Team • 12/12/2017
The vulnerability identified as CVE-2008-6662 represents a critical security flaw in AVG Anti-Virus for Linux version 7.5.51 and potentially earlier releases. This issue manifests through the improper handling of malformed UPX compressed files during the antivirus scanning process, creating a pathway for remote attackers to exploit the system. The vulnerability operates at the intersection of software decompression routines and memory management, where the antivirus engine fails to properly validate compressed file structures before processing them. The flaw specifically targets the UPX (Ultimate Packer for eXecutables) compression format, which is commonly used for packing executables to reduce file size or obfuscate code. When the antivirus software encounters a malformed UPX compressed file, the decompression routine becomes susceptible to memory corruption issues that can lead to system instability. This vulnerability directly maps to CWE-125, which describes out-of-bounds read conditions, and CWE-787, which addresses out-of-bounds writes in buffer operations. The attack vector is particularly concerning as it enables remote code execution or denial of service conditions without requiring local system access, making it a significant threat in networked environments where antivirus software processes files from untrusted sources.
The technical exploitation of this vulnerability occurs when the AVG Anti-Virus engine attempts to decompress a specially crafted UPX compressed file that contains malformed data structures. During the decompression process, the software's memory allocation and handling routines encounter unexpected data patterns that cause buffer overflows or invalid memory access operations. These memory corruption issues can manifest as segmentation faults that crash the antivirus process, resulting in denial of service conditions, or they can allow attackers to manipulate memory contents to execute arbitrary code within the context of the antivirus software. The vulnerability is particularly dangerous because it leverages legitimate file processing functionality to create an attack surface that can be exploited through network-based delivery methods. The memory corruption behavior aligns with ATT&CK technique T1059.007, which covers scripting languages and command execution, as the successful exploitation could enable attackers to execute malicious code through the compromised antivirus process. The vulnerability's impact extends beyond simple service disruption, as a successful exploit could provide attackers with elevated privileges within the antivirus environment, potentially leading to complete system compromise.
The operational impact of CVE-2008-6662 is substantial for organizations relying on AVG Anti-Virus for Linux as their primary endpoint protection solution. When exploited, this vulnerability can result in complete service disruption across affected systems, as the segmentation faults cause the antivirus daemon to crash repeatedly, leaving systems unprotected against malware threats. The potential for arbitrary code execution creates a more severe threat landscape, where attackers could use the vulnerability to establish persistent access to systems or deploy additional malicious payloads. Organizations using this antivirus version face increased risk of data breaches, system compromise, and operational downtime during exploitation attempts. The vulnerability's remote exploitability means that attackers do not need physical access to systems or knowledge of local credentials to initiate attacks. This makes the vulnerability particularly attractive to automated attack tools and malicious actors seeking to compromise multiple systems simultaneously. The impact is amplified in enterprise environments where antivirus software typically runs with elevated privileges, potentially providing attackers with additional attack surface opportunities. Security teams must consider the vulnerability's implications for their incident response procedures, as the denial of service aspect could mask other attack activities or prevent proper logging of malicious events. The vulnerability also impacts compliance requirements, as organizations may be unable to demonstrate adequate protection against known threats.
Mitigation strategies for CVE-2008-6662 focus primarily on immediate remediation through software updates and temporary operational controls. The most effective solution involves upgrading to a patched version of AVG Anti-Virus for Linux that addresses the memory handling issues in UPX decompression routines. Organizations should prioritize updating their antivirus software to the latest available version, as the vulnerability has been resolved in subsequent releases. Until updates can be deployed, administrators should implement network-based controls to restrict access to UPX compressed files from untrusted sources, particularly those that may contain malicious content. Network segmentation and firewall rules can help limit the exposure of affected systems to potentially harmful file transfers. Additionally, implementing file type filtering at network boundaries can prevent UPX compressed files from reaching systems that process them through antivirus software. System administrators should also consider disabling UPX decompression features in antivirus configurations where possible, though this may reduce overall detection capabilities. Monitoring for unusual antivirus process crashes or segmentation fault reports can help identify exploitation attempts, while implementing intrusion detection systems can provide additional layers of protection. The vulnerability highlights the importance of maintaining current antivirus signatures and software versions, as outdated security software often contains unpatched vulnerabilities that can be exploited by attackers. Organizations should also consider implementing application whitelisting policies to prevent execution of unknown or potentially malicious compressed files, reducing the attack surface for similar memory corruption vulnerabilities.