CVE-2010-2494 in bogofilter
Summary
by MITRE
Multiple buffer underflows in the base64 decoder in base64.c in (1) bogofilter and (2) bogolexer in bogofilter before 1.2.2 allow remote attackers to cause a denial of service (heap memory corruption and application crash) via an e-mail message with invalid base64 data that begins with an = (equals) character.
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Analysis
by VulDB Data Team • 01/23/2025
The vulnerability described in CVE-2010-2494 represents a critical buffer underflow flaw in the base64 decoding functionality of bogofilter and bogolexer components. This issue affects versions of the software prior to 1.2.2 and manifests when processing email messages containing malformed base64 encoded data. The vulnerability specifically exploits the handling of base64 data that begins with an equals sign character, which serves as a padding indicator in base64 encoding standards. The flaw resides in the base64.c implementation where insufficient input validation leads to improper memory management during the decoding process, creating conditions where heap memory can be corrupted through unauthorized write operations.
The technical exploitation of this vulnerability occurs through a carefully crafted email message containing invalid base64 data that starts with an equals character. When the bogofilter or bogolexer components attempt to process such data, the base64 decoder fails to properly validate the input sequence, leading to buffer underflow conditions. This type of memory corruption directly violates the principles of secure coding practices and falls under the CWE-121 category of stack-based buffer overflow, though in this case the manifestation occurs in heap memory. The vulnerability enables remote attackers to trigger application crashes and system instability by simply sending specially crafted email messages, making it particularly dangerous in email processing environments where automated filtering is employed.
The operational impact of CVE-2010-2494 extends beyond simple denial of service to potentially enable more sophisticated attack vectors. When the base64 decoder encounters the problematic input pattern, heap memory corruption can occur, leading to unpredictable application behavior and potential system crashes. This vulnerability directly impacts the availability and reliability of email filtering services that depend on bogofilter for spam detection. Organizations using affected versions face significant risk of service disruption, as attackers can repeatedly send malicious emails to exhaust system resources or cause application instability. The vulnerability also presents a potential pathway for privilege escalation attacks if the affected applications run with elevated permissions, though the primary impact remains focused on service availability and system stability.
Mitigation strategies for CVE-2010-2494 should prioritize immediate patching of affected systems to version 1.2.2 or later, which contains the necessary fixes for the base64 decoding implementation. Organizations should also implement additional input validation measures at network boundaries, filtering out suspicious email content that might trigger similar vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1499.004 for Network Denial of Service, and the remediation approach should include comprehensive testing of email filtering pipelines to ensure proper handling of malformed data. System administrators should also consider implementing intrusion detection systems that can identify patterns associated with this specific vulnerability, while maintaining regular security updates to prevent similar issues in other components of the email processing stack.