CVE-2012-1152 in Perl
Summary
by MITRE
Multiple format string vulnerabilities in the error reporting functionality in the YAML::LibYAML (aka YAML-LibYAML and perl-YAML-LibYAML) module 0.38 for Perl allow remote attackers to cause a denial of service (process crash) via format string specifiers in a (1) YAML stream to the Load function, (2) YAML node to the load_node function, (3) YAML mapping to the load_mapping function, or (4) YAML sequence to the load_sequence function.
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Analysis
by VulDB Data Team • 03/21/2021
The CVE-2012-1152 vulnerability represents a critical format string weakness in the YAML::LibYAML Perl module version 0.38, which serves as a core component for YAML parsing in numerous applications and systems. This vulnerability specifically targets the error reporting functionality within the module's parsing mechanisms, creating a pathway for remote attackers to exploit the system through carefully crafted malicious YAML input. The flaw manifests across multiple parsing functions including Load, load_node, load_mapping, and load_sequence, indicating a systemic issue within the module's handling of malformed input data. The vulnerability is categorized under CWE-134 which specifically addresses the use of format strings without proper validation, making it particularly dangerous as it can be leveraged for both denial of service and potentially more severe exploitation techniques.
The technical exploitation of this vulnerability occurs when the YAML::LibYAML module processes malformed input containing format string specifiers such as %s, %d, or other printf-style formatting directives. When these specifiers are encountered during the error reporting phase of YAML parsing, the module fails to properly sanitize the input before using it in printf or similar formatting functions. This improper handling causes the application to attempt to read memory locations specified by the format string directives, leading to segmentation faults and process crashes. The vulnerability affects not only the immediate parsing functions but also propagates through the error reporting mechanisms, making it difficult to contain and predict. Attackers can craft malicious YAML streams that trigger these format string vulnerabilities, causing applications using the module to crash and potentially leading to complete service disruption.
The operational impact of CVE-2012-1152 extends beyond simple denial of service scenarios, as it can be exploited to compromise the availability and stability of systems that rely on YAML parsing for configuration management, data exchange, or application initialization. Systems that process untrusted YAML input from external sources, such as web applications, configuration management tools, or data processing pipelines, become vulnerable to this attack vector. The vulnerability's reach is amplified by the widespread adoption of YAML as a data serialization format across various platforms and applications, including those implementing the ATT&CK technique of "Indicator Removal on Host" through the manipulation of configuration files or data structures. Organizations using affected versions of the YAML::LibYAML module face significant risk of service interruption, particularly in environments where YAML parsing is a critical component of system operations, potentially leading to cascading failures in dependent services.
Mitigation strategies for CVE-2012-1152 should prioritize immediate patching of the YAML::LibYAML module to version 0.39 or later, which contains the necessary fixes for the format string vulnerabilities. System administrators should implement input validation and sanitization measures for all YAML processing components, particularly those handling external or untrusted data sources. Additionally, organizations should consider implementing network segmentation and access controls to limit exposure to potentially malicious YAML input. The vulnerability highlights the importance of maintaining up-to-date dependencies and following secure coding practices such as those recommended in the OWASP Secure Coding Practices, which emphasize proper input validation and format string handling. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues in other components of the application stack, as this vulnerability demonstrates how seemingly minor flaws in parsing libraries can have significant operational consequences.