CVE-2010-3444 in pyfribidi
Summary
by MITRE
Buffer overflow in the log2vis_utf8 function in pyfribidi.c in GNU FriBidi 0.19.1, 0.19.2, and possibly other versions, as used in PyFriBidi 0.10.1, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted Arabic UTF-8 string that causes original 2-byte UTF-8 sequences to be transformed into 3-byte sequences.
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Analysis
by VulDB Data Team • 10/11/2021
The vulnerability identified as CVE-2010-3444 represents a critical buffer overflow flaw within the GNU FriBidi library's pyfribidi.c component. This issue affects versions 0.19.1 and 0.19.2 of the library, along with potentially other releases in the same series, and specifically impacts the PyFriBidi Python binding version 0.10.1. The flaw manifests in the log2vis_utf8 function which processes Unicode text for bidirectional layout rendering, a crucial function for handling text in languages that require complex text direction management such as Arabic and Hebrew.
The technical mechanism of this vulnerability involves improper handling of UTF-8 character sequences during the conversion process from original 2-byte UTF-8 representations to 3-byte sequences. When a specially crafted Arabic UTF-8 string is processed, the function fails to properly validate buffer boundaries, leading to memory corruption. This occurs because the implementation does not account for the potential expansion of character sequences during the transformation process, where two-byte UTF-8 sequences may be converted into three-byte representations, but the allocated buffer space does not accommodate this expansion. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which is a well-known weakness pattern in software security that occurs when more data is written to a buffer than it can hold, causing adjacent memory to be overwritten.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling remote code execution, making it particularly dangerous for applications that process untrusted text input. An attacker could exploit this flaw by submitting maliciously crafted Arabic text to any application that utilizes the affected FriBidi library, causing the application to crash or potentially execute arbitrary code with the privileges of the affected process. This vulnerability is particularly concerning in web applications, text processing systems, and any environment where user input is processed through bidirectional text rendering. The attack surface is broad given that FriBidi is used in numerous text processing applications and systems that require proper handling of right-to-left text languages.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems, as the most effective solution involves updating to a patched version of GNU FriBidi that properly handles UTF-8 sequence expansion during processing. Organizations should implement input validation measures that sanitize text input before processing, particularly for Unicode text that may trigger the vulnerable code path. Additionally, application-level protections such as stack canaries, address space layout randomization, and non-executable stack protections can provide defense-in-depth measures. From an ATT&CK perspective, this vulnerability maps to T1059.007 for command and scripting interpreter and T1499.004 for network denial of service, as it enables both system compromise and service disruption. System administrators should also consider implementing monitoring for unusual application crashes or memory access patterns that might indicate exploitation attempts, particularly in environments where bidirectional text processing is utilized.