CVE-2014-1928 in python-gnupg
Summary
by MITRE
The shell_quote function in python-gnupg 0.3.5 does not properly escape characters, which allows context-dependent attackers to execute arbitrary code via shell metacharacters in unspecified vectors, as demonstrated using "\" (backslash) characters to form multi-command sequences, a different vulnerability than CVE-2014-1927. NOTE: this vulnerability exists because of an incomplete fix for CVE-2013-7323.
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Analysis
by VulDB Data Team • 04/03/2022
The vulnerability identified as CVE-2014-1928 affects the python-gnupg library version 0.3.5 and represents a critical command injection flaw in the shell_quote function. This vulnerability stems from inadequate character escaping mechanisms that fail to properly sanitize input before shell execution, creating a pathway for attackers to execute arbitrary commands on affected systems. The flaw specifically manifests when shell metacharacters are processed through the library's quote handling mechanism, allowing malicious actors to craft inputs that bypass intended security boundaries and escalate privileges.
The technical implementation of this vulnerability demonstrates a failure in input validation and sanitization practices within the cryptographic library's shell interaction layer. When the shell_quote function processes user-provided data, it does not adequately escape special shell characters including backslashes, which can be exploited to create multi-command sequences that execute unintended operations. This vulnerability operates under the context-dependent attack model where the malicious input must be processed through the vulnerable function to achieve code execution, making it particularly dangerous in environments where the library handles untrusted data from external sources.
From an operational impact perspective, this vulnerability exposes systems using python-gnupg to potential remote code execution attacks, especially in scenarios where the library processes data from network sources or user inputs without proper validation. The vulnerability's exploitation requires attackers to understand the specific shell quoting mechanics and craft inputs that leverage the incomplete fix from CVE-2013-7323, which had addressed similar issues but failed to cover all edge cases. Systems running vulnerable versions of python-gnupg are at risk of complete compromise when the library is used in applications that process untrusted data through the affected shell_quote function.
The root cause of this vulnerability aligns with CWE-78, which specifically addresses improper neutralization of special elements used in OS commands, and demonstrates the challenges in implementing robust shell escaping mechanisms. This flaw represents a regression in security posture following the previous fix for CVE-2013-7323, indicating that security patches must be comprehensive and thoroughly tested against all potential attack vectors. The vulnerability also relates to ATT&CK technique T1059.001, which covers command and scripting interpreter execution, as attackers can leverage this flaw to execute arbitrary commands through shell interactions. Organizations should immediately upgrade to patched versions of python-gnupg and implement additional input validation measures to prevent exploitation of this and similar command injection vulnerabilities in their cryptographic processing workflows.
The vulnerability's persistence in the software ecosystem highlights the complexity of shell injection prevention and the importance of maintaining consistent security practices throughout software development lifecycles. Security teams must recognize that fixes for similar vulnerabilities may not be complete and require ongoing monitoring and testing to ensure that all potential attack vectors are properly addressed. This particular vulnerability serves as a reminder of the critical importance of thorough regression testing in security patches and the need for comprehensive security reviews of input handling mechanisms in cryptographic libraries that interface with system shells.