CVE-2008-1807 in FreeType
Summary
by MITRE
FreeType2 before 2.3.6 allow context-dependent attackers to execute arbitrary code via an invalid "number of axes" field in a Printer Font Binary (PFB) file, which triggers a free of arbitrary memory locations, leading to memory corruption.
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Analysis
by VulDB Data Team • 08/12/2019
The vulnerability identified as CVE-2008-1807 represents a critical memory corruption flaw within the FreeType2 font rendering library version 2.3.5 and earlier. This issue manifests when processing Printer Font Binary PFB files, which are commonly used for printer fonts and contain font data in a specific binary format. The vulnerability stems from inadequate input validation within the font parsing mechanism, specifically in how the library handles the "number of axes" field within PFB file structures.
The technical exploitation of this vulnerability occurs through a context-dependent attack vector where malicious actors craft specially formatted PFB files containing an invalid "number of axes" field value. When the FreeType2 library attempts to parse this malformed field, it triggers a memory management error where the library frees memory at arbitrary locations rather than the intended memory regions. This arbitrary memory deallocation creates a condition where memory corruption can occur, potentially allowing attackers to execute arbitrary code with the privileges of the affected application.
The operational impact of this vulnerability extends beyond simple code execution, as it can be leveraged in various attack scenarios including privilege escalation and system compromise. The vulnerability affects applications that utilize FreeType2 for font rendering, which includes web browsers, office suites, desktop environments, and other software that processes font files. The context-dependent nature of the attack means that successful exploitation requires specific conditions related to how the font data is processed and interpreted by the target application, making it particularly challenging to defend against in complex software environments.
This vulnerability maps to CWE-125, which describes out-of-bounds read conditions, and CWE-476, which covers null pointer dereference issues. The attack pattern aligns with ATT&CK technique T1059.007 for command and scripting interpreter, where adversaries might leverage memory corruption to execute malicious code through compromised applications. The flaw demonstrates a classic buffer over-read vulnerability that occurs during font parsing operations, where the library fails to properly validate the boundaries of expected data structures. Security professionals should note that this vulnerability represents a significant risk in environments where users might encounter untrusted font files, particularly in web browsing scenarios where font rendering is frequently required. The remediation strategy involves upgrading to FreeType2 version 2.3.6 or later, which implements proper input validation and memory management safeguards. Additionally, organizations should implement defensive measures such as restricting font file processing in untrusted environments and monitoring for unusual memory allocation patterns in applications using FreeType2 libraries.