CVE-2012-5468 in Bogofilter
Summary
by MITRE
Heap-based buffer overflow in iconvert.c in the bogolexer component in Bogofilter before 1.2.3 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via an email containing a base64 string that is decoded to incomplete multibyte characters.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability described in CVE-2012-5468 represents a critical heap-based buffer overflow within the bogolexer component of Bogofilter email filtering software. This flaw exists in the iconvert.c file and affects versions prior to 1.2.3, creating a significant security risk for email systems that rely on this spam filtering technology. The vulnerability stems from inadequate handling of base64 encoded strings during the decoding process, specifically when these strings are transformed into incomplete multibyte characters that exceed allocated memory boundaries.
The technical implementation of this vulnerability involves the improper validation of decoded base64 content within the email processing pipeline. When Bogofilter encounters an email containing a specially crafted base64 string, the iconvert.c component attempts to decode this content and convert it to multibyte character representations. However, the memory allocation routines fail to properly account for the potential expansion of decoded data into multibyte sequences, particularly when the decoded content contains incomplete multibyte characters that cannot be properly represented within the allocated heap buffers. This fundamental flaw in memory management creates a condition where the program writes beyond the bounds of allocated memory regions, leading to unpredictable behavior.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially enable remote code execution. Attackers can exploit this weakness by crafting malicious email messages that contain specifically formatted base64 strings designed to trigger the buffer overflow during processing. When the affected Bogofilter system processes such emails, the heap corruption can cause application crashes and, in some scenarios, provide attackers with opportunities to inject and execute arbitrary code on the target system. This makes the vulnerability particularly dangerous in environments where email filtering systems are central to security infrastructure and where automated processing of incoming mail is routine.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, heap-based buffer overflow, and demonstrates characteristics consistent with ATT&CK technique T1190 for exploit development and T1499 for denial of service. The attack surface is broad as it affects any system running vulnerable versions of Bogofilter, particularly those in enterprise environments where email filtering is critical. Organizations using this software face potential compromise of email systems, disruption of communication services, and possible lateral movement opportunities if successful exploitation leads to code execution. The vulnerability's remote nature means that attackers do not require physical access or local privileges to exploit the flaw, making it particularly concerning for networked environments.
Mitigation strategies for CVE-2012-5468 primarily involve immediate patching of affected systems to version 1.2.3 or later, which includes proper bounds checking and memory allocation routines for handling multibyte character conversions. System administrators should also implement email filtering rules that can identify and quarantine suspicious base64 encoded content, though this approach provides only partial protection as the vulnerability exists within the core processing logic. Additionally, monitoring for unusual application crashes or memory allocation patterns can help detect exploitation attempts. The vulnerability highlights the importance of proper input validation and memory management in security-critical applications, particularly those handling untrusted data from network sources. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts.