CVE-2005-3239 in ClamAV
Summary
by MITRE
The OLE2 unpacker in clamd in Clam AntiVirus (ClamAV) 0.87-1 allows remote attackers to cause a denial of service (segmentation fault) via a DOC file with an invalid property tree, which triggers an infinite recursion in the ole2_walk_property_tree function.
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Analysis
by VulDB Data Team • 07/19/2024
The vulnerability identified as CVE-2005-3239 represents a critical denial of service flaw within the Clam AntiVirus 0.87-1 implementation. This issue specifically targets the OLE2 unpacker component of clamd, which is responsible for processing OLE2 structured storage files including Microsoft Office documents. The vulnerability manifests when the system encounters DOC files containing malformed property trees that trigger improper recursive function calls within the ole2_walk_property_tree function.
The technical root cause of this vulnerability stems from insufficient input validation within the OLE2 parsing logic. When processing a specially crafted DOC file with an invalid property tree structure, the ole2_walk_property_tree function enters an infinite recursion loop due to inadequate boundary checks and termination conditions. This recursive behavior consumes excessive system resources and ultimately leads to a segmentation fault, causing the clamd daemon to crash and terminate unexpectedly. The vulnerability operates at the application layer within the anti-virus scanning engine, making it particularly dangerous as it can be exploited through standard document delivery mechanisms.
The operational impact of this vulnerability extends beyond simple service disruption, as it creates a potential vector for denial of service attacks against systems relying on ClamAV for document scanning. Attackers can craft malicious DOC files that, when processed by vulnerable ClamAV installations, will cause the scanning daemon to become unresponsive and require manual restart. This vulnerability affects organizations that depend on real-time document scanning capabilities, as the service interruption can lead to delayed threat detection and potential security gaps. The flaw particularly impacts environments where automatic document processing occurs, such as email gateways, file servers, or web applications that handle user-uploaded office documents.
Security practitioners should implement immediate mitigations including updating to ClamAV versions that contain patches for this vulnerability, typically those released after the vulnerability disclosure. The fix involves adding proper bounds checking and recursion depth limitations within the ole2_walk_property_tree function to prevent infinite recursion scenarios. Additionally, implementing network-level filtering to block suspicious document types or employing sandboxing techniques for document analysis can provide additional defense-in-depth measures. Organizations should also consider monitoring for unusual clamd daemon restart patterns or segmentation fault occurrences that may indicate exploitation attempts. This vulnerability aligns with CWE-674, which addresses Uncontrolled Recursion, and represents a classic example of how improper input validation can lead to resource exhaustion and service disruption. The ATT&CK framework categorizes this as a Denial of Service technique under the T1499 category, specifically targeting service availability through application-level exploitation.