CVE-2011-4104 in Django Tastypie
Summary
by MITRE
The from_yaml method in serializers.py in Django Tastypie before 0.9.10 does not properly deserialize YAML data, which allows remote attackers to execute arbitrary Python code via vectors related to the yaml.load method.
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Analysis
by VulDB Data Team • 04/03/2022
The vulnerability identified as CVE-2011-4104 affects Django Tastypie versions prior to 0.9.10 and represents a critical security flaw in the YAML deserialization process. This vulnerability stems from the insecure implementation of the from_yaml method within the serializers.py file, which directly utilizes the yaml.load method without proper sanitization or restriction of loaded objects. The flaw creates a path for remote code execution attacks by allowing malicious actors to craft specially crafted YAML payloads that, when processed by the vulnerable method, can trigger arbitrary Python code execution on the target system.
The technical root cause of this vulnerability aligns with CWE-502, which describes "Deserialization of Untrusted Data" as a weakness that occurs when untrusted data is deserialized without proper validation or sanitization. When the yaml.load method processes malicious input, it can instantiate arbitrary Python objects and execute code during the deserialization process. This behavior is particularly dangerous because YAML's flexible nature allows for the creation of complex object graphs that can include callable objects, class constructors, and other dangerous elements that can be exploited to gain unauthorized access or execute malicious commands on the server.
The operational impact of this vulnerability is severe and far-reaching within the context of web applications using Django Tastypie for API services. Attackers can exploit this flaw by sending specially crafted YAML data to endpoints that utilize the affected from_yaml method, potentially leading to complete system compromise. The vulnerability affects applications that accept and process external YAML data through the Tastypie API framework, making it particularly dangerous for services that expose RESTful interfaces or accept configuration data from untrusted sources. The remote nature of the attack means that exploitation can occur from any location without requiring local access to the system, significantly expanding the attack surface.
This vulnerability demonstrates the critical importance of proper input validation and secure deserialization practices in web applications. The attack vector is consistent with techniques described in the MITRE ATT&CK framework under the Tactic of Execution, specifically targeting the use of legitimate system tools and libraries for malicious purposes. Organizations using Django Tastypie should implement immediate mitigations including upgrading to version 0.9.10 or later, which contains the necessary security patches to prevent the unsafe YAML deserialization. Additional defensive measures include implementing proper input validation for all external data sources, restricting YAML parsing to safe subsets, and employing sandboxing techniques to limit the potential impact of any successful exploitation attempts. The vulnerability also underscores the need for regular security assessments and dependency updates to prevent similar issues from arising in other components of the application stack.