CVE-2014-10071 in zsh
Summary
by MITRE
In exec.c in zsh before 5.0.7, there is a buffer overflow for very long fds in the ">& fd" syntax.
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2014-10071 represents a critical buffer overflow flaw within the zsh shell's execution component, specifically affecting versions prior to 5.0.7. This issue manifests when processing very long file descriptor specifications using the ">& fd" syntax, where the shell fails to properly validate input length before attempting to store data in a fixed-size buffer. The flaw exists in the exec.c source file, which handles command execution and file descriptor management within the zsh shell environment. Such buffer overflow conditions create opportunities for arbitrary code execution and system compromise when exploited by malicious actors.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the shell's parsing logic for file descriptor redirection operations. When zsh encounters the ">& fd" syntax with excessively long file descriptor identifiers, it attempts to process these inputs without sufficient bounds checking, leading to memory corruption in the buffer allocated for storing file descriptor information. This buffer overflow directly violates fundamental security principles of memory safety and input validation, creating potential exploitation vectors for attackers to manipulate program execution flow. The vulnerability aligns with CWE-121, which describes buffer overflow conditions where insufficient bounds checking allows data to overwrite adjacent memory locations, and also corresponds to ATT&CK technique T1059.006 for command and scripting interpreter usage.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it provides attackers with potential pathways to execute arbitrary code with the privileges of the affected zsh process. Systems running vulnerable zsh versions are particularly at risk when processing untrusted input or when users have the ability to execute shell commands. The vulnerability could be exploited in various contexts including web applications that utilize zsh for command execution, automated scripts, or any environment where user-supplied file descriptor specifications might be processed. Attackers could leverage this flaw to escalate privileges, gain unauthorized access to system resources, or establish persistent backdoors within affected environments.
Mitigation strategies for CVE-2014-10071 primarily focus on immediate patch application to upgrade to zsh version 5.0.7 or later, which includes proper bounds checking and input validation for file descriptor operations. System administrators should also implement input sanitization measures at higher levels of the application stack to prevent malicious file descriptor specifications from reaching the shell interpreter. Additional defensive measures include restricting shell access for untrusted users, implementing proper privilege separation, and monitoring for anomalous file descriptor usage patterns. Organizations should conduct comprehensive vulnerability assessments to identify all systems running vulnerable zsh versions and prioritize remediation efforts accordingly. The fix implemented in version 5.0.7 demonstrates proper memory management practices and adherence to secure coding guidelines that prevent similar buffer overflow conditions from occurring in future implementations.