CVE-2007-1351 in OpenBSD
Summary
by MITRE
Integer overflow in the bdfReadCharacters function in bdfread.c in (1) X.Org libXfont before 20070403 and (2) freetype 2.3.2 and earlier allows remote authenticated users to execute arbitrary code via crafted BDF fonts, which result in a heap overflow.
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Analysis
by VulDB Data Team • 07/17/2019
The vulnerability identified as CVE-2007-1351 represents a critical integer overflow flaw within the font handling subsystem of widely used open source software components. This issue affects X.Org libXfont versions prior to 20070403 and freetype versions 2.3.2 and earlier, creating a dangerous condition that can be exploited by remote authenticated attackers to achieve arbitrary code execution. The vulnerability stems from improper input validation within the bdfReadCharacters function located in bdfread.c, which processes Bitmap Distribution Format fonts that are commonly used in X Window System environments and font rendering applications.
The technical implementation of this vulnerability involves an integer overflow condition that occurs when processing malformed BDF font files. When the bdfReadCharacters function encounters crafted font data, it fails to properly validate the size parameters of character data structures, leading to an arithmetic overflow that results in heap corruption. This heap overflow condition creates memory corruption that can be leveraged by attackers to overwrite critical memory locations, potentially allowing them to execute malicious code with the privileges of the affected application. The vulnerability specifically manifests when the system attempts to allocate memory blocks based on computed values that exceed the maximum representable integer values, causing the allocation to fail or produce incorrect memory mappings that can be manipulated by attackers.
The operational impact of CVE-2007-1351 extends beyond simple denial of service scenarios, as it enables remote code execution capabilities that can compromise entire systems. Attackers exploiting this vulnerability can manipulate the font rendering process to inject malicious code into memory spaces controlled by font processing applications. This creates a significant threat vector for attackers who can leverage the vulnerability through legitimate font handling channels, particularly in environments where users might encounter untrusted font files from web sources or network locations. The vulnerability is particularly concerning in server environments or applications that process font files from untrusted sources, as it can be exploited without requiring special privileges beyond authentication access to the system.
Security professionals should implement immediate mitigations including updating to patched versions of affected software components, specifically X.Org libXfont version 20070403 or later and freetype versions 2.3.3 or later. Network segmentation and access controls should be implemented to limit exposure of systems that process font files, while input validation measures should be strengthened to prevent malformed font data from reaching vulnerable processing functions. The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and represents a classic example of memory safety issues that can lead to arbitrary code execution in font rendering systems. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and code injection, with potential for lateral movement when exploited in multi-system environments where font processing occurs across various applications and services. Organizations should also consider implementing monitoring for unusual font processing activities and memory allocation patterns that might indicate exploitation attempts.