CVE-2007-4510 in ClamAV
Summary
by MITRE
ClamAV before 0.91.2, as used in Kolab Server 2.0 through 2.2beta1 and other products, allows remote attackers to cause a denial of service (application crash) via (1) a crafted RTF file, which triggers a NULL dereference in the cli_scanrtf function in libclamav/rtf.c; or (2) a crafted HTML document with a data: URI, which triggers a NULL dereference in the cli_html_normalise function in libclamav/htmlnorm.c. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 07/21/2021
The vulnerability identified as CVE-2007-4510 represents a critical denial of service weakness affecting ClamAV versions prior to 0.91.2, particularly impacting Kolab Server 2.0 through 2.2beta1 and other software utilizing this antivirus engine. This flaw manifests through two distinct attack vectors that exploit NULL dereference conditions within ClamAV's document parsing mechanisms, creating opportunities for remote attackers to disrupt service availability. The vulnerability operates at the core of ClamAV's document analysis capabilities, specifically targeting functions responsible for processing rich text format and html content, making it particularly dangerous in email and file scanning environments where such document types are commonly encountered.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within ClamAV's parsing libraries. When processing a specially crafted RTF file, the cli_scanrtf function in libclamav/rtf.c encounters a NULL pointer dereference condition that causes the application to crash and terminate unexpectedly. Similarly, when handling HTML documents containing data: URIs, the cli_html_normalise function in libclamav/htmlnorm.c experiences the same NULL dereference issue. Both scenarios involve the software attempting to access memory locations that have not been properly initialized or validated, resulting in application instability. This type of vulnerability maps directly to CWE-476 which describes NULL Pointer Dereference, and represents a classic example of improper input validation leading to denial of service conditions. The flaw demonstrates poor defensive programming practices where the code fails to adequately check for null pointer conditions before dereferencing pointers during document processing operations.
The operational impact of CVE-2007-4510 extends beyond simple application crashes to create significant service disruption in environments relying on ClamAV for security scanning. In email server deployments, attackers could send malicious RTF or HTML emails that would cause the antivirus software to crash, effectively rendering the email scanning service unavailable until manual intervention occurs. This creates a denial of service scenario that can be exploited to disrupt legitimate email services, potentially affecting business continuity and communication infrastructure. The vulnerability is particularly concerning because it can be triggered remotely without requiring authentication or special privileges, making it an attractive target for automated attacks. From an attacker's perspective, this represents a low-effort, high-impact method of service disruption that aligns with ATT&CK technique T1499.004 for network denial of service attacks. The vulnerability affects organizations that depend on ClamAV for content filtering, as the crash conditions can be triggered through legitimate email or file transfer operations, creating both operational and security implications.
Mitigation strategies for CVE-2007-4510 focus on immediate remediation through software updates and defensive configuration measures. The primary and most effective solution involves upgrading to ClamAV version 0.91.2 or later, where the NULL dereference conditions have been addressed through proper input validation and memory management. Organizations should implement automated patch management processes to ensure timely deployment of security updates across all systems utilizing ClamAV. Additionally, defensive measures can include implementing strict content filtering policies that limit the processing of untrusted RTF and HTML documents, particularly those containing data: URIs. Network-level protections such as implementing rate limiting for email scanning operations and deploying intrusion detection systems that can identify suspicious document patterns may provide additional layers of defense. Security monitoring should include logging of antivirus crashes and service disruptions to detect potential exploitation attempts. The vulnerability highlights the importance of proper input validation and defensive programming practices, reinforcing the need for regular security assessments of core system components and maintaining updated security software to prevent exploitation of known vulnerabilities.