CVE-2012-6123 in CHICKEN
Summary
by MITRE
Chicken before 4.8.0 does not properly handle NUL bytes in certain strings, which allows an attacker to conduct "poisoned NUL byte attack."
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/01/2024
The vulnerability identified as CVE-2012-6123 affects the Chicken Scheme implementation version 4.8.0 and earlier, presenting a critical security flaw in string handling operations. This vulnerability stems from the improper management of null bytes within string processing functions, creating a pathway for attackers to exploit the system through what is termed a "poisoned NUL byte attack." The issue resides in the fundamental string parsing mechanisms of the Chicken interpreter, where null characters are not adequately sanitized or handled during string operations, leading to potential code execution or memory corruption scenarios.
The technical flaw manifests when Chicken processes strings containing null bytes in specific contexts, particularly within functions that manipulate string data or perform pattern matching operations. When a null byte is encountered within a string that the interpreter processes, the system fails to properly terminate string operations or validate the integrity of the string data. This creates a condition where an attacker can inject malicious null bytes into string inputs, potentially causing the interpreter to misinterpret subsequent data as part of the string or to bypass security checks. The vulnerability is classified under CWE-129 as an insufficient input validation, specifically related to improper handling of null terminators in string operations, which represents a fundamental flaw in input sanitization practices.
The operational impact of this vulnerability extends beyond simple string processing failures and can potentially enable arbitrary code execution within the context of the Chicken interpreter. Attackers can leverage this weakness to manipulate interpreter behavior, bypass access controls, or execute malicious code by carefully crafting inputs that contain null bytes in strategic positions. The attack vector typically involves feeding specially crafted strings containing null bytes into the interpreter, which can cause unpredictable behavior including buffer overflows, memory corruption, or execution of unintended code paths. This vulnerability affects any application or system that relies on Chicken Scheme for processing user input or dynamic code generation, potentially compromising the entire execution environment.
Mitigation strategies for CVE-2012-6123 require immediate implementation of the vendor-provided patch for Chicken version 4.8.0 or later, which addresses the null byte handling issue through proper input validation and string sanitization. Organizations should also implement input filtering mechanisms to sanitize all string inputs before processing, particularly when dealing with user-supplied data. The remediation process involves updating to the patched version of Chicken Scheme, followed by comprehensive testing of all applications that utilize the interpreter to ensure the vulnerability has been properly addressed. Additionally, system administrators should monitor for any unauthorized access attempts or anomalous behavior that might indicate exploitation attempts, as the vulnerability could be leveraged in conjunction with other attack vectors. This vulnerability aligns with ATT&CK technique T1059.007 for script-based execution and T1021.004 for remote services, as exploitation typically involves manipulating interpreter behavior through crafted inputs to achieve unauthorized code execution.