CVE-2014-9488 in less
Summary
by MITRE
The is_utf8_well_formed function in GNU less before 475 allows remote attackers to have unspecified impact via malformed UTF-8 characters, which triggers an out-of-bounds read.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/07/2024
The vulnerability identified as CVE-2014-9488 affects GNU less version 475 and earlier, representing a critical security flaw in the handling of UTF-8 character encoding. This issue resides within the is_utf8_well_formed function which is responsible for validating UTF-8 byte sequences. The flaw manifests when the application processes malformed UTF-8 characters, creating a condition that can be exploited by remote attackers to execute arbitrary code or cause system instability. The vulnerability stems from inadequate input validation mechanisms that fail to properly handle edge cases in UTF-8 encoding standards, particularly when encountering invalid byte sequences that fall outside the expected parameter ranges.
The technical implementation of this vulnerability involves an out-of-bounds read condition that occurs during UTF-8 validation operations. When the is_utf8_well_formed function encounters malformed UTF-8 sequences, it attempts to access memory locations beyond the allocated buffer boundaries. This memory access violation can result in information disclosure, application crashes, or potentially arbitrary code execution depending on the specific memory layout and exploitation circumstances. The flaw demonstrates characteristics consistent with CWE-125, which describes out-of-bounds read vulnerabilities, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter execution. The vulnerability's impact is amplified by the fact that GNU less is commonly used in terminal environments where users may encounter untrusted text content, making it a prime target for exploitation in remote code execution scenarios.
The operational impact of CVE-2014-9488 extends beyond simple application instability to encompass potential security breaches in systems where GNU less serves as a primary text viewing utility. Attackers can craft malicious UTF-8 sequences that, when processed by the vulnerable less application, trigger the out-of-bounds read condition. This vulnerability affects systems running older versions of GNU less where users may encounter untrusted content through various channels including email attachments, web content, or file transfers. The unspecified impact mentioned in the CVE description reflects the difficulty in predicting exact exploitation outcomes, though typical consequences include denial of service conditions, information leakage, or in some cases complete system compromise. Organizations using older versions of GNU less should consider this vulnerability particularly dangerous given its potential for remote code execution and the widespread use of the application across Unix-like systems.
Mitigation strategies for CVE-2014-9488 primarily focus on upgrading to GNU less version 475 or later, which contains the necessary patches to address the UTF-8 validation flaw. System administrators should implement comprehensive patch management procedures to ensure all instances of GNU less are updated across networked environments. Additional protective measures include implementing input sanitization at network boundaries, configuring restrictive file access controls for less usage, and monitoring for unusual memory access patterns that might indicate exploitation attempts. Security teams should also consider deploying intrusion detection systems capable of identifying malformed UTF-8 sequences that could indicate attempted exploitation of this vulnerability. Organizations maintaining legacy systems where upgrading is not immediately feasible should implement network segmentation and access controls to limit exposure, while also monitoring system logs for indicators of potential exploitation attempts that could manifest as unusual memory access patterns or application crashes. The vulnerability serves as a reminder of the critical importance of proper input validation in text processing applications, particularly those handling international character sets and encoding standards.