CVE-2014-9274 in UnRTF
Summary
by MITRE
UnRTF allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code as demonstrated by a file containing the string "{\cb-999999999".
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Analysis
by VulDB Data Team • 04/07/2022
The vulnerability identified as CVE-2014-9274 resides within the UnRTF library, a widely used open-source tool for converting Rich Text Format documents into various other formats including plain text and HTML. This library serves as a critical component in many document processing pipelines and is often integrated into larger software ecosystems for handling office document conversions. The flaw manifests as a heap-based buffer overflow that occurs when UnRTF processes specially crafted RTF files containing malformed data structures. The vulnerability specifically affects the parsing logic that handles certain RTF control words and their associated parameters, creating a condition where insufficient input validation allows malicious data to overwrite adjacent memory regions. This type of vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking permits memory corruption. The attack vector is particularly dangerous because it can be exploited through simple file manipulation without requiring any special privileges or complex attack chains.
The technical implementation of this vulnerability involves the manipulation of RTF control words that are designed to control formatting parameters within rich text documents. When UnRTF encounters a malformed control word sequence that includes the string "{", it fails to properly validate the length of subsequent data structures, leading to a buffer overflow that can corrupt the program's memory space. The heap corruption occurs because the library allocates memory based on assumptions about input data size, but malicious input causes the allocation to be insufficient for the actual data being processed. This memory corruption can result in unpredictable program behavior, including crashes that manifest as denial of service conditions or more severe outcomes where attackers can potentially inject and execute arbitrary code within the context of the UnRTF process. The vulnerability is particularly concerning because RTF files are commonly encountered in email attachments, file sharing systems, and document management applications, providing multiple attack surfaces for exploitation. According to the ATT&CK framework, this vulnerability maps to the T1059.007 technique for command and scripting interpreter, as it enables remote code execution through manipulated document processing, and also relates to T1499.004 for network denial of service.
The operational impact of CVE-2014-9274 extends far beyond simple service disruption, as it represents a critical security weakness that can be leveraged for more sophisticated attacks within targeted environments. Organizations that rely on UnRTF for document conversion services face significant risks, as attackers can craft malicious RTF files that trigger the buffer overflow condition when processed by vulnerable systems. The potential for remote code execution means that compromised systems could be used as launching points for further attacks within network infrastructures, making this vulnerability particularly attractive to threat actors. The vulnerability affects not only standalone UnRTF applications but also any software that incorporates the library into its document processing capabilities, including email servers, document management systems, and content filtering appliances. The exploitability of this vulnerability is enhanced by the fact that RTF files are commonly accepted and processed by numerous applications without extensive validation, creating widespread exposure across different computing environments. Security professionals must consider this vulnerability in their risk assessments, as it can be exploited through simple social engineering campaigns targeting end users who may unknowingly open malicious RTF files, thereby providing threat actors with unauthorized access to systems. The vulnerability also highlights the importance of input validation in document processing libraries, as the lack of proper bounds checking in parsing functions creates opportunities for memory corruption attacks that can be systematically exploited across different implementations.
Mitigation strategies for CVE-2014-9274 should focus on immediate remediation through software updates and comprehensive input validation measures. The primary solution involves upgrading to patched versions of UnRTF that include proper bounds checking and memory allocation safeguards to prevent the heap overflow conditions from occurring. Organizations should also implement defensive measures such as restricting RTF file processing capabilities in critical systems and deploying content filtering solutions that can identify and quarantine suspicious RTF files before they reach vulnerable applications. Network-based protections can include implementing sandboxing mechanisms for RTF file analysis and configuring email security appliances to scan and block potentially malicious RTF attachments. Additionally, system administrators should consider disabling RTF processing capabilities in applications where such functionality is not essential, reducing the attack surface available to potential exploiters. The implementation of proper input validation techniques, including bounds checking for all user-supplied data and the use of secure coding practices, should be enforced throughout software development processes to prevent similar vulnerabilities from being introduced in future implementations. Regular security assessments and penetration testing should be conducted to identify and remediate any remaining vulnerabilities in document processing pipelines, ensuring that systems remain protected against both known and emerging threats in the evolving cybersecurity landscape.