CVE-2007-1671 in AntiVir
Summary
by MITRE
avpack32.dll before 7.3.0.6 in Avira AntiVir allows remote attackers to cause a denial of service (infinite loop) via a ZOO archive with a direntry structure that points to a previous file.
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Analysis
by VulDB Data Team • 01/09/2017
The vulnerability identified as CVE-2007-1671 affects the avpack32.dll component within Avira AntiVir software versions prior to 7.3.0.6. This flaw resides in the handling of ZOO archive format files and represents a classic case of improper input validation that can be exploited to trigger a denial of service condition. The vulnerability specifically targets the archive extraction and processing routines within the anti-virus engine's file handling capabilities, where the software fails to properly validate the directory entry structure of ZOO archives.
The technical implementation of this vulnerability involves a maliciously crafted ZOO archive containing a direntry structure that creates a circular reference pointing to a previous file within the same archive. When the Avira AntiVir scanner attempts to process this archive, the avpack32.dll module enters an infinite loop during the directory traversal process. This occurs because the software does not implement proper loop detection mechanisms when following file references within the archive structure. The flaw stems from inadequate boundary checking and reference validation in the archive parsing logic, which allows attackers to construct archive entries that cause the processing routine to continuously iterate through the same file references without termination.
From an operational perspective, this vulnerability presents a significant risk to organizations relying on Avira AntiVir for endpoint protection, as remote attackers can trigger a denial of service condition without requiring any special privileges or authentication. The infinite loop consumes system resources and can lead to complete service unavailability, potentially affecting multiple endpoints simultaneously if the malicious archive is distributed through email attachments, web downloads, or other common attack vectors. The impact extends beyond simple service disruption as it can affect system performance, network availability, and overall security operations, particularly in environments where automated scanning processes are critical for threat detection.
The vulnerability aligns with CWE-835, which describes the weakness of infinite loops or iterations without proper termination conditions, and represents a clear example of how improper validation of structured data can lead to resource exhaustion attacks. From the MITRE ATT&CK framework perspective, this vulnerability could be leveraged during the execution phase of an attack, specifically through the use of malicious files that trigger denial of service conditions, potentially enabling attackers to disrupt security operations and create opportunities for additional exploitation attempts. Organizations should implement immediate mitigations including updating to Avira AntiVir version 7.3.0.6 or later, which contains the necessary patch to address the circular reference handling in ZOO archive processing. Additionally, network administrators should consider implementing additional layers of protection such as email filtering rules and file type restrictions to prevent the delivery of potentially malicious archive files to endpoints, while also monitoring for unusual system behavior that might indicate exploitation attempts.