CVE-2005-1922 in ClamAV
Summary
by MITRE
The MS-Expand file handling in Clam AntiVirus (ClamAV) before 0.86 allows remote attackers to cause a denial of service (file descriptor and memory consumption) via a crafted file that causes repeated errors in the cli_msexpand function.
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Analysis
by VulDB Data Team • 07/05/2021
The vulnerability identified as CVE-2005-1922 represents a critical denial of service weakness in Clam AntiVirus versions prior to 0.86, specifically within the MS-Expand file handling component. This flaw resides in the cli_msexpand function which processes Microsoft-specific file formats during virus scanning operations. The vulnerability stems from inadequate input validation and error handling mechanisms that fail to properly manage malformed or crafted MS-Expand files, creating a scenario where malicious actors can exploit the software's processing logic to consume excessive system resources.
The technical implementation of this vulnerability involves the manipulation of file descriptors and memory allocation patterns within the ClamAV scanning engine. When a crafted MS-Expand file is processed, the cli_msexpand function enters a loop of repeated error conditions that cause the application to continuously allocate memory resources without proper cleanup or termination. This results in progressive memory exhaustion and file descriptor depletion, ultimately leading to system instability and complete service unavailability. The flaw operates at the protocol level where the software fails to implement proper bounds checking and resource management when encountering malformed file structures, making it particularly dangerous in automated scanning environments.
From an operational impact perspective, this vulnerability creates significant risk for organizations relying on ClamAV for email filtering, file system scanning, and network security monitoring. The denial of service condition can be triggered remotely through various attack vectors including email attachments, web downloads, or file transfers, making it particularly dangerous in enterprise environments where continuous security operations are critical. The resource consumption patterns associated with this vulnerability can cause cascading failures in security infrastructure, potentially affecting multiple systems that depend on the availability of the scanning service. Network administrators face the challenge of maintaining security coverage while dealing with the potential for service disruption that this vulnerability introduces.
The vulnerability aligns with CWE-129, which addresses improper validation of input boundaries, and demonstrates characteristics consistent with ATT&CK technique T1499.004 for network denial of service. Organizations should implement immediate mitigation strategies including updating to ClamAV version 0.86 or later, implementing network-based filtering to block suspicious file types, and establishing monitoring protocols to detect unusual memory consumption patterns. Additionally, security teams should consider implementing redundant scanning systems and establishing incident response procedures to handle potential service disruptions caused by this vulnerability. The remediation process requires careful consideration of the update deployment schedule to avoid introducing additional service interruptions while ensuring comprehensive protection against the identified threat vector.