CVE-2007-2973 in Antivir Antivirus
Summary
by MITRE
Avira Antivir Antivirus before 7.03.00.09 allows remote attackers to cause a denial of service (infinite loop and CPU consumption) via a malformed TAR archive.
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Analysis
by VulDB Data Team • 07/20/2021
The vulnerability identified as CVE-2007-2973 represents a significant denial of service weakness in Avira Antivir Antivirus software prior to version 7.03.00.09. This flaw specifically targets the software's handling of TAR archive files, which are commonly used compressed file formats in Unix and Linux environments. The vulnerability manifests when the antivirus engine encounters a malformed TAR archive that triggers an infinite loop during the decompression and analysis process, resulting in excessive cpu consumption that can bring the system to a halt.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within the antivirus decompression routines. When processing a specially crafted TAR archive, the parsing logic fails to properly validate the archive structure, leading to a condition where the decompression algorithm enters an infinite loop. This occurs because the malformed archive contains recursive or self-referential structures that cause the antivirus engine to continuously process the same data segments without proper termination conditions. The flaw operates at the level of archive parsing and decompression, which is a critical function for antivirus software that must analyze potentially malicious files from various formats.
From an operational impact perspective, this vulnerability presents a severe threat to system availability and performance. Attackers can exploit this weakness remotely by simply delivering a malformed TAR file to a system running the vulnerable Avira Antivirus version, requiring no additional privileges or complex attack vectors. The resulting infinite loop consumes cpu resources at maximum capacity, effectively rendering the system unresponsive or significantly degraded in performance. This type of denial of service attack can be particularly devastating in enterprise environments where antivirus systems are deployed across multiple endpoints, potentially causing widespread service disruption.
The vulnerability aligns with CWE-835, which describes the weakness of an infinite loop in software, and demonstrates how improper input validation can lead to resource exhaustion attacks. According to ATT&CK framework, this represents a denial of service technique that can be classified under T1499.004 - Endpoint Denial of Service, where adversaries leverage software weaknesses to consume system resources. The attack vector is particularly concerning as it requires no user interaction beyond the delivery of the malicious file, making it an effective method for causing system disruption. Organizations should note that this vulnerability specifically affects legacy versions of Avira Antivirus, highlighting the importance of maintaining current software versions and applying security patches promptly.
Mitigation strategies for this vulnerability primarily focus on immediate software updates to versions 7.03.00.09 or later where the issue has been resolved. System administrators should implement network monitoring to detect unusual cpu consumption patterns that might indicate exploitation attempts. Additional protective measures include implementing network segmentation to limit the impact of successful attacks and deploying multiple layers of security controls. The fix typically involves strengthening the archive parsing logic to properly validate archive structures and implement timeout mechanisms to prevent indefinite processing of malformed files. Organizations should also consider implementing automated patch management systems to ensure all antivirus software remains up to date with the latest security fixes.