CVE-2008-3243 in scanning engine
Summary
by MITRE
Multiple unspecified vulnerabilities in the scanning engine before 4.4.4 in F-Prot Antivirus before 6.0.9.0 allow remote attackers to cause a denial of service via (1) a crafted UPX-compressed file, which triggers an engine crash; (2) a crafted Microsoft Office file, which triggers an infinite loop; or (3) an ASPack-compressed file, which triggers an engine crash.
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Analysis
by VulDB Data Team • 08/14/2019
The vulnerability identified as CVE-2008-3243 represents a critical weakness in the F-Prot Antivirus scanning engine that existed prior to version 4.4.4 and affected F-Prot Antivirus versions before 6.0.9.0. This issue demonstrates the inherent risks associated with antivirus software's handling of compressed and office documents, where the scanning engine becomes vulnerable to maliciously crafted files that exploit implementation flaws in the decompression and analysis processes. The vulnerability classifies under CWE-129, which deals with insufficient validation of length parameters, and specifically relates to improper handling of compressed file formats that can lead to buffer overflows or infinite loops during processing.
The technical exploitation of this vulnerability occurs through three distinct attack vectors that target different aspects of the scanning engine's operation. The first vector involves crafted UPX-compressed files that trigger engine crashes, indicating that the decompression routine lacks proper bounds checking or error handling when processing malformed compressed data. The second vector utilizes specially crafted Microsoft Office files designed to induce infinite loops within the scanning engine, suggesting that the document parsing logic does not adequately validate or limit recursive operations during content analysis. The third vector employs ASPack-compressed files that also cause engine crashes, demonstrating that the vulnerability is not limited to a single compression format but affects multiple compression methods used by malware authors to evade detection.
From an operational impact perspective, this vulnerability creates a significant risk for organizations relying on F-Prot Antivirus for protection, as remote attackers can cause denial of service conditions that effectively disable the antivirus scanning capabilities. The infinite loop attack vector poses particular concern as it can consume system resources and potentially cause system instability or complete system hangs, while the engine crash scenarios can lead to complete service interruption. These vulnerabilities align with ATT&CK technique T1499.001, which covers network denial of service attacks, and T1070.004, which involves the manipulation of existing programs to execute malicious code. The attack surface is particularly concerning because it allows remote exploitation without requiring authentication, making it a prime target for automated attacks.
The root cause of these vulnerabilities stems from inadequate input validation and error handling within the antivirus engine's decompression and document parsing routines. When the scanning engine encounters malformed compressed files or specially crafted office documents, the lack of proper bounds checking and recursive loop limiting allows attackers to manipulate the engine's behavior. The vulnerability demonstrates how compression formats that are typically used for legitimate software distribution can be weaponized against antivirus systems, creating a paradox where the very tools designed to protect against malicious software become vulnerable to exploitation. Organizations should consider implementing layered security approaches that include network segmentation, application whitelisting, and regular security updates to mitigate the risk of exploitation. The fix requires comprehensive input validation across all decompression routines and implementation of proper timeout mechanisms for document parsing operations to prevent infinite loops and resource exhaustion attacks.