A vulnerability in the Excel XLM macro parsing module in Clam AntiVirus (ClamAV) Software versions 0.103.0 and 0.103.1 could allow an unauthenticated, remote attacker to cause a denial of service condition on an affected device. The vulnerability is due to improper error handling that may result in an infinite loop. An attacker could exploit this vulnerability by sending a crafted Excel file to an affected device. An exploit could allow the attacker to cause the ClamAV scanning process to hang, resulting in a denial of service condition.
The CVSS score for this vulnerability is 7.5, indicating high severity. This score reflects significant risks, specifically in terms of availability impact, which is rated as high. Organizations using affected versions of ClamAV should be aware of the potential for disruption to their scanning services, which could lead to extended periods of unavailability.
Currently, there are no known exploits in the wild, but the nature of the vulnerability makes it a potential target for attackers. Organizations should prioritize patching immediately to prevent any possible exploitation that could lead to a denial of service event.
Given the high severity and the potential for significant impact, it is crucial for organizations to remain vigilant and ensure their systems are up-to-date with the latest security patches from ClamAV.
Vulnerability Details
The vulnerability is classified under CWE-20 (Improper Input Validation) and CWE-835 (Infinite Loop). The specific versions of ClamAV affected are 0.103.0 and 0.103.1. The vulnerability was published on April 8, 2021, and has been modified since its initial release.
Technical Analysis
The root cause of this vulnerability stems from improper error handling within the Excel XLM macro parsing module. When an affected device attempts to process a specially crafted Excel file, the error handling mechanism fails, leading to an infinite loop that causes the ClamAV scanning process to hang.
The attack vector is network-based, with low complexity. No privileges are required, and user interaction is not necessary for the exploitation to succeed. This means that an attacker could remotely trigger this vulnerability without needing to authenticate.
The impact on availability is rated as high due to the possibility of a complete denial of service, where the scanning process cannot be completed, affecting the overall security posture of the organization.
Risk & Impact Analysis
Risk to organizations includes potential downtime of critical antivirus services, which could expose systems to unscanned threats. The blast radius for this vulnerability can be significant, especially in environments relying heavily on ClamAV for malware detection and prevention.
Organizations should assess their usage of ClamAV and prioritize updating to the fixed version as part of their patch management process. The urgency for remediation is high, considering the potential for disruption and the need to maintain operational integrity.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of ClamAV are 0.103.0 and 0.103.1. Organizations should upgrade to the latest version to mitigate this vulnerability.
Mitigation & Remediation
Organizations should implement the following steps to mitigate this vulnerability:
1. Upgrade to ClamAV version 0.103.2 or later.
2. Monitor logs for unusual activities related to Excel file processing.
3. Implement network controls to limit exposure to untrusted files.
For further guidance on security assessments, organizations can refer to our penetration testing services.
Detection Guidance
Organizations should monitor for the following indicators:
1. Logs showing repeated failures in processing Excel files.
2. Anomalies in the ClamAV scanning logs, especially around the time of received Excel files.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of robust error handling and the need for proactive security measures in software development. Organizations should regularly review and update their security practices to address emerging threats.
The growing trend of remote attacks necessitates a focus on network security and continuous vulnerability assessments. For more information on enhancing your security posture, consider our vulnerability management program and the importance of ongoing security assessments.
Adopting strategies for comprehensive security testing can help organizations mitigate risks associated with vulnerabilities like CVE-2021-1252. For detailed guidance, refer to our penetration testing methodology and ensure robust defenses.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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