CVE-2007-4578 in Sophos
Summary
by MITRE
Sophos Anti-Virus for Windows and for Unix/Linux before 2.48.0 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted UPX packed file, resulting from an "integer cast around". NOTE: as of 20070828, the vendor says this is a DoS and the researcher says this allows code execution, but the researcher is reliable.
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Analysis
by VulDB Data Team • 07/25/2019
The vulnerability identified as CVE-2007-4578 affects Sophos Anti-Virus products running on both Windows and Unix/Linux platforms, specifically versions prior to 2.48.0. This security flaw represents a critical issue that demonstrates how seemingly benign file processing operations can be exploited to compromise system integrity and availability. The vulnerability manifests when the anti-virus software encounters a specially crafted UPX packed file, which is a common compression utility used by both legitimate software distributors and malicious actors to obfuscate executable content.
The technical root cause of this vulnerability lies in what is termed an "integer cast around" flaw, which falls under the category of integer overflow conditions and represents a variant of the broader class of integer arithmetic errors. This type of vulnerability occurs when a program performs operations on integer values that exceed the maximum or minimum limits of the data type being used, leading to unexpected behavior when the value wraps around or is cast to a different data type. In the context of Sophos Anti-Virus, this flaw specifically impacts how the software processes compressed file headers and metadata, particularly when dealing with UPX packed executables that contain malformed or oversized integer fields.
The operational impact of this vulnerability extends beyond simple denial of service, as the security researcher's assessment indicates potential for arbitrary code execution. When an attacker crafts a malicious UPX packed file with carefully manipulated integer values, the anti-virus software's unpacking routine can be forced to execute code outside of its intended boundaries. This creates a scenario where the very security tool designed to protect the system becomes a vector for compromise, potentially allowing attackers to execute malicious code with the privileges of the anti-virus process. The vulnerability's classification aligns with CWE-190, which specifically addresses integer overflow conditions, and could be mapped to ATT&CK technique T1059.007 for execution through multiple mechanisms.
The exploitability of this vulnerability is particularly concerning because UPX packed files are commonly encountered in legitimate software distributions, making it difficult for users to distinguish between benign and malicious files. Attackers could leverage this vulnerability by distributing software that appears legitimate but contains the maliciously crafted UPX packed file, potentially compromising systems that are actively protected by Sophos Anti-Virus. The integer cast around issue demonstrates how defensive software can become a point of ingress for attackers, highlighting the importance of thorough input validation and proper bounds checking in security applications. Organizations should prioritize immediate patching to version 2.48.0 or later, as this vulnerability represents a significant risk to system security and availability, particularly in environments where automated threat detection is critical for maintaining operational continuity.
This vulnerability serves as a stark reminder of the complexities involved in developing robust security software, where the tools designed to protect systems can themselves contain flaws that attackers can exploit. The remediation process requires not only updating the anti-virus software but also implementing additional monitoring and validation procedures to detect potential exploitation attempts. The security community should consider this case study when evaluating similar vulnerabilities in other security tools, emphasizing the need for comprehensive testing of input handling mechanisms and the importance of maintaining up-to-date security solutions to prevent exploitation of known vulnerabilities.