CVE-2005-0249 in AntiVirus
Summary
by MITRE
Heap-based buffer overflow in the DEC2EXE module for Symantec AntiVirus Library allows remote attackers to execute arbitrary code via a UPX compressed file containing a negative virtual offset to a crafted PE header.
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Analysis
by VulDB Data Team • 07/05/2025
The vulnerability described in CVE-2005-0249 represents a critical heap-based buffer overflow within the DEC2EXE module of Symantec AntiVirus Library, specifically affecting the handling of UPX compressed files. This flaw exists in the way the antivirus software processes executable files that have been compressed using the UPX packer, creating a dangerous condition where malicious actors can exploit the software's decompression routine to gain remote code execution privileges. The vulnerability stems from insufficient input validation when processing PE (Portable Executable) headers within compressed files, allowing attackers to craft malicious payloads that manipulate the virtual offset values in the PE header structure.
The technical implementation of this vulnerability involves a heap-based buffer overflow that occurs during the decompression process of UPX compressed files. When Symantec AntiVirus Library encounters a UPX compressed file, it attempts to parse the PE header structure to determine how to properly decompress and analyze the executable. The flaw manifests when the virtual offset field in the PE header contains a negative value, which causes the application to allocate insufficient memory for the heap buffer. This improper memory allocation creates a condition where subsequent data processing operations can overwrite adjacent memory locations, potentially allowing an attacker to inject and execute arbitrary code with the privileges of the antivirus process. The vulnerability is classified under CWE-121 as a heap-based buffer overflow, which is a well-documented weakness in memory management practices.
The operational impact of this vulnerability is severe and far-reaching, particularly in enterprise environments where Symantec AntiVirus products are widely deployed. Attackers can exploit this weakness by crafting UPX compressed files with malicious PE headers that contain negative virtual offset values, enabling them to remotely execute arbitrary code on systems running vulnerable versions of Symantec AntiVirus. This creates a significant risk for organizations as the exploitation could occur through various attack vectors including email attachments, web downloads, or removable media, potentially leading to full system compromise, data exfiltration, or establishment of persistent backdoors. The vulnerability affects the core antivirus functionality and essentially allows attackers to bypass the very security measures designed to protect systems from malicious code execution.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Symantec AntiVirus products, as the vendor would have released a security update addressing the heap buffer overflow condition. Organizations should also implement network-level controls to block UPX compressed files from entering the network perimeter, particularly in environments where the antivirus software is not immediately patched. Additional defensive measures include implementing strict file type validation, monitoring for unusual file decompression patterns, and ensuring that antivirus software is configured to handle compressed files with appropriate sandboxing or isolation techniques. From an ATT&CK framework perspective, this vulnerability maps to technique T1059.007 for execution through command and scripting interpreter and T1204.002 for user execution through malicious file, demonstrating how attackers can leverage antivirus software weaknesses to establish persistent access and execute malicious payloads. The vulnerability highlights the importance of secure coding practices and proper input validation in security software, as even defensive tools can contain exploitable flaws that attackers can leverage against the very systems they are designed to protect.