CVE-2014-9652 in PHP
Summary
by MITRE
The mconvert function in softmagic.c in file before 5.21, as used in the Fileinfo component in PHP before 5.4.37, 5.5.x before 5.5.21, and 5.6.x before 5.6.5, does not properly handle a certain string-length field during a copy of a truncated version of a Pascal string, which might allow remote attackers to cause a denial of service (out-of-bounds memory access and application crash) via a crafted file.
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Analysis
by VulDB Data Team • 03/09/2022
The vulnerability identified as CVE-2014-9652 resides within the file command's magic file processing functionality, specifically in the mconvert function located in softmagic.c. This flaw affects PHP versions prior to 5.4.37, 5.5.21, and 5.6.5, where the Fileinfo component utilizes the file command's magic file parsing capabilities. The vulnerability manifests when processing certain file types that contain specially crafted Pascal strings with truncated length fields, creating a scenario where memory boundaries are improperly validated during string copying operations. This issue represents a classic buffer over-read condition that can be exploited by remote attackers to disrupt service availability.
The technical root cause stems from improper handling of string-length fields during Pascal string processing within the magic file parsing logic. When the mconvert function encounters a Pascal string with a truncated length field, it fails to properly validate the length parameter before proceeding with memory copy operations. The flaw occurs because the function does not adequately check whether the specified string length exceeds the actual available buffer space, leading to out-of-bounds memory access patterns. This type of vulnerability maps directly to CWE-125, which describes out-of-bounds read conditions, and can be categorized under the broader ATT&CK technique T1499.004 for network denial of service attacks. The improper validation of input parameters during string processing creates a pathway for attackers to manipulate memory access patterns and trigger application instability.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as it can lead to complete application crashes and system instability when exploited. Remote attackers can craft malicious files that, when processed by PHP's Fileinfo component, will trigger the buffer over-read condition and cause the application to terminate unexpectedly. This creates significant availability risks for web applications that rely on file type detection for security validation, file upload restrictions, or content handling. The vulnerability is particularly concerning in environments where PHP processes user-uploaded files or handles file metadata from untrusted sources, as it can be leveraged to disrupt critical services or potentially enable more sophisticated attack vectors if combined with other vulnerabilities. The impact is amplified when considering that many web applications depend on PHP's file type detection capabilities for security decisions and content filtering.
Mitigation strategies for CVE-2014-9652 focus primarily on upgrading affected PHP installations to patched versions that contain proper bounds checking in the magic file processing logic. System administrators should prioritize updating their PHP environments to versions 5.4.37, 5.5.21, or 5.6.5, respectively, depending on their current PHP version. Additionally, implementing proper input validation and sanitization measures can help reduce the attack surface by limiting the types of files processed through the Fileinfo component. Organizations should also consider deploying network-based intrusion detection systems that can identify suspicious file patterns associated with this vulnerability. The fix implemented in patched versions typically involves adding proper bounds checking before string copy operations and ensuring that length fields are validated against actual buffer boundaries, effectively preventing the out-of-bounds memory access that enables the denial of service condition. Security monitoring should include detection of abnormal application crashes or memory access patterns that may indicate exploitation attempts.