CVE-2005-2385 in Avast Antivirus
Summary
by MITRE
Buffer overflow in a third-party compression library (UNACEV2.DLL), as used in avast! Antivirus Home/Professional Edition 4.6.665 and Server Edition 4.6.460, allows remote attackers to execute arbitrary code via an ACE archive containing a long filename.
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Analysis
by VulDB Data Team • 07/27/2017
The vulnerability identified as CVE-2005-2385 represents a critical buffer overflow flaw within the UNACEV2.DLL compression library component that forms part of the avast! Antivirus software suite. This issue affects multiple versions including the Home/Professional Edition 4.6.665 and Server Edition 4.6.460, creating a significant security risk for organizations and individual users who rely on these antivirus solutions for protection. The vulnerability stems from inadequate input validation within the ACE archive processing functionality, specifically when handling filenames that exceed predetermined buffer limits. The flaw manifests when the antivirus software attempts to decompress or analyze an ACE archive containing a maliciously crafted filename that surpasses the allocated memory buffer space.
The technical implementation of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. The attack vector leverages remote code execution capabilities through network-based delivery of malicious ACE archives, making it particularly dangerous for enterprise environments where automated threat detection and response systems may be compromised. When the vulnerable avast! software processes an ACE archive with an excessively long filename, the buffer overflow occurs during the filename parsing routine within the UNACEV2.DLL library, potentially allowing attackers to overwrite adjacent memory locations with malicious code. This memory corruption can be exploited to redirect program execution flow and ultimately achieve arbitrary code execution on the targeted system.
The operational impact of this vulnerability extends beyond simple exploitation, as it compromises the integrity of the antivirus protection mechanism itself. Since avast! antivirus software is designed to detect and neutralize threats, a successful exploitation of CVE-2005-2385 essentially undermines the very security layer that users depend upon for protection. Attackers can leverage this vulnerability to bypass traditional antivirus defenses, install persistent backdoors, or escalate privileges within the compromised system. The remote nature of the attack means that threat actors can exploit this vulnerability without requiring physical access to the target machine, making it particularly attractive for large-scale attacks. Additionally, the vulnerability affects both client and server editions of the software, indicating a widespread impact across different deployment scenarios and potentially enabling attackers to target critical infrastructure components.
Organizations affected by this vulnerability should implement immediate mitigations including patching the avast Antivirus that contain fixes for the third-party compression library. System administrators should also consider implementing network-based controls such as content filtering and sandboxing techniques to prevent the execution of potentially malicious ACE archives. From an ATT&CK framework perspective, this vulnerability maps to techniques involving execution through command and scripting interpreter and privilege escalation, while also enabling initial access through malicious file delivery methods. Security monitoring should include detection of unusual decompression activities and potential buffer overflow indicators within antivirus log files, as well as network traffic analysis for suspicious ACE archive transfers that could indicate exploitation attempts.