CVE-2007-2972 in AntiVir
Summary
by MITRE
The file parsing engine in Avira Antivir Antivirus before 7.04.00.24 allows remote attackers to cause a denial of service (application crash) via a crafted UPX compressed file, which triggers a divide-by-zero error.
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Analysis
by VulDB Data Team • 07/20/2019
The vulnerability identified as CVE-2007-2972 represents a critical flaw in the file parsing engine of Avira Antivir Antivirus software prior to version 7.04.00.24. This issue manifests as a denial of service condition that can be triggered remotely through the deliberate crafting of UPX compressed files. The vulnerability stems from inadequate input validation and error handling within the antivirus engine's decompression and file analysis routines. When the maliciously crafted UPX compressed file is processed by the affected antivirus software, the parsing engine encounters a condition that leads to a divide-by-zero error, ultimately causing the application to crash and terminate unexpectedly.
The technical exploitation of this vulnerability occurs during the file decompression and analysis phase of the antivirus scanning process. UPX (Ultimate Packer for eXecutables) is a popular open-source executable packer that compresses executable files to reduce their size while maintaining functionality. When Avira Antivir processes such compressed files, the parsing engine attempts to analyze the compressed structure and extract information for threat detection. The flaw arises when the engine encounters a specific pattern within the UPX compressed file that results in a mathematical operation attempting to divide by zero, which is an undefined operation that typically causes program termination. This divide-by-zero error represents a classic software bug that demonstrates poor error handling and input validation practices within the antivirus engine's file processing pipeline.
The operational impact of CVE-2007-2972 extends beyond simple application instability, as it can be leveraged by remote attackers to disrupt security operations and potentially compromise system availability. In enterprise environments where antivirus software serves as a critical security control, such a vulnerability can be exploited to create service disruption attacks that prevent legitimate security scanning operations from functioning properly. The vulnerability's remote exploitability means that attackers can deliver malicious UPX compressed files through various channels including email attachments, web downloads, or file sharing systems without requiring local access to the target system. This characteristic makes the vulnerability particularly dangerous in networked environments where automated scanning and security monitoring systems may be repeatedly targeted, leading to cascading failures in security infrastructure.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-369, which describes the "Divide By Zero" weakness in software systems. The flaw also maps to ATT&CK technique T1499.004, which covers "Endpoint Denial of Service" through the exploitation of application vulnerabilities. Organizations that deploy Avira Antivir Antivirus software prior to the patched version 7.04.00.24 face significant risk of experiencing service interruptions and potential security gaps during the periods when the vulnerability remains unpatched. The vulnerability demonstrates the critical importance of robust input validation and error handling in security software, as even benign file processing operations can become attack vectors when proper safeguards are not implemented.
Mitigation strategies for CVE-2007-2972 primarily focus on immediate software updates and patches provided by Avira. System administrators should prioritize deployment of the patched version 7.04.00.24 or later, which includes proper input validation and error handling mechanisms to prevent the divide-by-zero condition from occurring. Additionally, organizations should implement network-level controls to block or scan UPX compressed files before they reach endpoint systems, particularly in environments where immediate patch deployment may not be feasible. Monitoring and logging should be enhanced to detect unusual patterns of antivirus engine crashes or service disruptions that might indicate exploitation attempts. The vulnerability also underscores the importance of maintaining current antivirus signatures and ensuring that security software vendors provide timely updates to address newly discovered flaws in their products, as this represents a fundamental weakness in the security software's ability to process legitimate and potentially malicious files without system instability.