CVE-2011-0020 in pango
Summary
by MITRE
Heap-based buffer overflow in the pango_ft2_font_render_box_glyph function in pango/pangoft2-render.c in libpango in Pango 1.28.3 and earlier, when the FreeType2 backend is enabled, allows user-assisted remote attackers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted font file, related to the glyph box for an FT_Bitmap object.
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Analysis
by VulDB Data Team • 09/22/2024
The vulnerability identified as CVE-2011-0020 represents a critical heap-based buffer overflow within the Pango text rendering library, specifically affecting versions 1.28.3 and earlier. This flaw exists in the pango_ft2_font_render_box_glyph function located in pango/pangoft2-render.c, which handles font rendering operations when the FreeType2 backend is active. The vulnerability stems from inadequate bounds checking during the processing of glyph box information for FT_Bitmap objects, creating a scenario where maliciously crafted font files can trigger memory corruption. The flaw operates at the intersection of font rendering and memory management, where the application fails to validate the size parameters of glyph box dimensions before attempting to copy data into heap-allocated buffers.
The technical exploitation of this vulnerability requires a user-assisted remote attacker to provide a specially crafted font file that triggers the vulnerable code path when the affected Pango library processes text rendering operations. When the pango_ft2_font_render_box_glyph function encounters malformed glyph box data within the FT_Bitmap object, it attempts to copy data into a heap buffer without proper size validation, resulting in a buffer overflow condition. This overflow can corrupt adjacent memory regions, leading to unpredictable application behavior. The vulnerability's impact extends beyond simple denial of service, as the heap corruption can potentially be leveraged for arbitrary code execution, depending on the specific memory layout and exploitation conditions present during the overflow event.
The operational impact of CVE-2011-0020 manifests across various applications and systems that rely on Pango for text rendering, including web browsers, desktop applications, and document processing software. Attackers can exploit this vulnerability by delivering malicious font files through various attack vectors such as email attachments, web downloads, or compromised websites. The vulnerability's classification as a heap-based buffer overflow aligns with CWE-121, which describes heap-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent heap memory. This flaw directly relates to ATT&CK technique T1059.007 for execution through scripting and T1203 for exploitation of vulnerabilities in rendering libraries. The vulnerability affects systems running affected versions of Pango, particularly those utilizing the FreeType2 backend for font rendering, making it a widespread concern for applications that process untrusted font content.
Mitigation strategies for CVE-2011-0020 primarily focus on upgrading to patched versions of the Pango library, specifically version 1.28.4 or later, which contain the necessary bounds checking fixes for the vulnerable function. System administrators should implement comprehensive patch management procedures to ensure all affected applications are updated promptly. Additional protective measures include implementing strict input validation for font files, utilizing sandboxing techniques for font processing operations, and deploying network-based intrusion detection systems that can identify and block malicious font file deliveries. Organizations should also consider implementing application whitelisting policies that restrict font processing to trusted sources and validate font file integrity before processing. The vulnerability's remediation aligns with industry best practices for memory safety and follows the principle of least privilege in font processing operations, reducing the attack surface and minimizing potential exploitation success rates.