CVE-2007-0886 in Axigen Mail Server
Summary
by MITRE
Heap-based buffer underflow in axigen 1.2.6 through 2.0.0b1 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via certain base64-encoded data on the pop3 port (110/tcp), which triggers an integer overflow.
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Analysis
by VulDB Data Team • 08/22/2024
The vulnerability identified as CVE-2007-0886 represents a critical heap-based buffer underflow affecting Axigen email server versions 1.2.6 through 2.0.0b1. This flaw exists within the application's handling of base64-encoded data transmitted over the POP3 port, specifically on TCP port 110. The vulnerability operates through a sophisticated chain of memory corruption that begins with the processing of malformed base64 input, leading to integer overflow conditions that ultimately result in heap corruption. The attack vector is particularly concerning as it allows remote exploitation without authentication requirements, making it accessible to any attacker with network access to the target system.
The technical implementation of this vulnerability stems from improper input validation and memory management within Axigen's POP3 service implementation. When the server receives base64-encoded data through the POP3 protocol, it fails to properly validate the length and encoding of the input before processing it within heap-allocated buffers. The integer overflow occurs during the calculation of buffer sizes or array indices, where the overflowed integer value becomes negative or exceeds the expected range, leading to insufficient buffer allocation. This miscalculation causes subsequent memory operations to write data beyond the allocated heap boundaries, creating a heap-based buffer underflow condition that can be exploited to manipulate memory contents.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable remote code execution, making it a particularly dangerous flaw in email server infrastructure. When exploited, the buffer underflow can cause application crashes that result in service disruption, but more critically, the heap corruption can be manipulated to overwrite critical memory structures or function pointers. This memory corruption capability provides attackers with the potential to execute arbitrary code with the privileges of the Axigen service account, which typically runs with elevated system permissions. The vulnerability affects the core POP3 functionality, making it a persistent threat to email server availability and security.
The vulnerability aligns with CWE-121, Heap-based Buffer Overflow, and CWE-129, Improper Validation of Array Index, while also demonstrating characteristics consistent with ATT&CK technique T1203, Exploitation for Client Execution. The integer overflow condition that precedes the buffer underflow is a common pattern in memory corruption vulnerabilities and represents a fundamental flaw in input sanitization and boundary checking. Organizations running affected Axigen versions face significant risk as this vulnerability can be exploited by attackers to gain unauthorized access to email infrastructure, potentially leading to data breaches, email spoofing, or further network compromise. The vulnerability's remote exploitability and potential for code execution make it particularly attractive to threat actors targeting enterprise email systems.
Mitigation strategies for CVE-2007-0886 require immediate patching of affected Axigen installations to versions that address the buffer overflow and integer overflow conditions. System administrators should implement network segmentation to limit access to the POP3 port, particularly when the vulnerability cannot be immediately patched. Additionally, monitoring for suspicious base64-encoded traffic patterns on port 110 can help detect exploitation attempts. The implementation of input validation controls and regular security assessments of email server configurations provides additional defense layers against similar vulnerabilities. Organizations should also consider deploying intrusion detection systems capable of identifying malformed base64 data patterns that could indicate exploitation attempts against this and related vulnerabilities.