CVE-2017-6310 in tnef
Summary
by MITRE
An issue was discovered in tnef before 1.4.13. Four type confusions have been identified in the file_add_mapi_attrs() function. These might lead to invalid read and write operations, controlled by an attacker.
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Analysis
by VulDB Data Team • 08/17/2020
The vulnerability identified in CVE-2017-6310 represents a critical type confusion flaw within the tnef library version 1.4.12 and earlier, affecting systems that process Transport Neutral Encapsulation Format files commonly used in Microsoft Exchange environments. This issue manifests specifically within the file_add_mapi_attrs() function where multiple type confusion vulnerabilities exist, creating opportunities for attackers to manipulate memory operations through crafted malicious input files. The vulnerability stems from improper type handling during attribute processing, allowing attackers to control invalid read and write operations that could potentially lead to arbitrary code execution or system compromise.
The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers buffer overflow vulnerabilities in heap data structures. These type confusion issues occur when the application fails to properly validate data types during processing, allowing an attacker to manipulate the execution flow by providing malicious input that causes the program to interpret data as different types than intended. The specific function file_add_mapi_attrs() processes MAPI (Messaging Application Programming Interface) attributes within TNEF files, and the type confusion occurs during the handling of various attribute types that should be strictly validated.
From an operational impact perspective, this vulnerability creates significant risk for email servers and client applications that process TNEF files, particularly in enterprise environments where Microsoft Exchange servers handle large volumes of email traffic. Attackers could exploit this vulnerability by crafting malicious TNEF attachments that trigger the type confusion during attribute processing, potentially leading to remote code execution, denial of service, or information disclosure. The vulnerability's exploitation requires an attacker to have the ability to deliver a specially crafted TNEF file to a target system, making it particularly concerning for email security and spam filtering systems.
The mitigation strategy for CVE-2017-6310 involves immediate upgrade to tnef version 1.4.13 or later, which contains the necessary patches to address the type confusion vulnerabilities. Organizations should also implement network-level controls to restrict access to TNEF file processing capabilities and consider deploying email filtering solutions that can identify and block suspicious TNEF attachments. Security teams should monitor for exploitation attempts and implement proper input validation controls for any applications that process TNEF formatted data. This vulnerability demonstrates the importance of proper type validation in memory management and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation could potentially lead to command execution through memory corruption attacks. The vulnerability also relates to ATT&CK technique T1203 for exploitation for privilege escalation, as successful exploitation could provide attackers with elevated system privileges.