CVE-2022-23318 in pcf2bdf
Summary
by MITRE • 02/17/2022
A heap-buffer-overflow in pcf2bdf, versions >= 1.05 allows an attacker to trigger unsafe memory access via a specially crafted PCF font file. This out-of-bound read may lead to an application crash, information disclosure via program memory or other context-dependent impact.
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Analysis
by VulDB Data Team • 02/19/2022
The heap-buffer-overflow vulnerability in pcf2bdf represents a critical memory safety issue that affects versions 1.05 and later of this font conversion utility. This vulnerability resides within the handling of PCF (Portable Compiled Format) font files, which are commonly used in X Window System environments for font representation. The flaw manifests when the utility processes malformed input files, specifically those that have been crafted to exploit the memory access patterns within the application's heap allocation mechanisms.
The technical implementation of this vulnerability stems from insufficient bounds checking during the parsing of PCF font headers and data structures. When pcf2bdf encounters a specially crafted PCF file, it attempts to read data beyond the allocated buffer boundaries, leading to unpredictable memory access patterns. This heap-based buffer overflow occurs because the application fails to validate the size parameters specified in the PCF file format headers before performing memory operations. The vulnerability is categorized under CWE-121 as a heap-based buffer overflow, which directly relates to improper handling of dynamic memory allocation and insufficient validation of input data structures.
The operational impact of this vulnerability extends beyond simple application crashes, presenting significant security implications for systems that process untrusted font data. An attacker could potentially exploit this weakness to achieve arbitrary code execution, though the specific vector requires careful exploitation due to modern memory protection mechanisms. The vulnerability may also enable information disclosure attacks where adjacent memory regions containing sensitive data could be read through the out-of-bounds memory access. This type of vulnerability falls under the ATT&CK technique T1059.007 for command and scripting interpreter, as it could be leveraged in automated exploitation scenarios targeting font processing pipelines in desktop environments or web applications that handle font rendering.
Mitigation strategies for this vulnerability encompass multiple layers of defense including immediate version updates to patched releases of pcf2bdf, implementation of input validation controls, and deployment of memory protection mechanisms such as stack canaries and address space layout randomization. System administrators should also consider implementing sandboxing techniques for font processing utilities and establishing strict file format validation procedures. The vulnerability highlights the importance of proper input sanitization in font processing applications and demonstrates how seemingly benign file format parsing can become a vector for serious security compromises. Organizations relying on X Window System font handling should conduct comprehensive vulnerability assessments of their font processing pipelines and implement monitoring for suspicious file processing activities.