CVE-2011-4213 in App Engine Python SDK
Summary
by MITRE
The sandbox environment in the Google App Engine Python SDK before 1.5.4 does not properly prevent use of the os module, which allows local users to bypass intended access restrictions and execute arbitrary commands via a file_blob_storage.os reference within the code parameter to _ah/admin/interactive/execute, a different vulnerability than CVE-2011-1364.
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Analysis
by VulDB Data Team • 01/28/2018
The vulnerability described in CVE-2011-4213 represents a critical sandbox escape flaw within the Google App Engine Python SDK that existed prior to version 1.5.4. This security weakness specifically targets the sandbox environment's inability to properly restrict access to the os module, creating a pathway for malicious actors to circumvent intended security controls. The vulnerability manifests through a specific attack vector involving the file_blob_storage.os reference within the code parameter of the _ah/admin/interactive/execute endpoint, which operates outside the scope of the primary vulnerability referenced in CVE-2011-1364.
The technical implementation of this vulnerability exploits the insufficient sandbox isolation mechanisms that should have prevented direct system calls and file operations from within the development environment. Attackers can leverage this flaw by crafting malicious code that references the os module through the file_blob_storage.os pathway, effectively bypassing the sandbox's intended restrictions. This allows unauthorized execution of arbitrary commands on the underlying system, as the sandbox fails to properly validate or restrict access to operating system level functionalities. The vulnerability specifically targets the Python SDK's administrative interface, where interactive code execution capabilities are exposed to developers for debugging and testing purposes.
The operational impact of CVE-2011-4213 extends beyond simple privilege escalation, as it enables full system compromise through local code execution. An attacker with access to the development environment or the ability to submit malicious code through the interactive execution interface can gain complete control over the host system, potentially leading to data exfiltration, system corruption, or further lateral movement within the network. This vulnerability undermines the fundamental security assumptions of the Google App Engine development environment, where sandboxing is expected to prevent unauthorized system access. The flaw particularly affects developers who may inadvertently expose the interactive execution interface or who lack proper security awareness regarding the potential consequences of executing untrusted code within the development environment.
Mitigation strategies for CVE-2011-4213 require immediate application of the vendor-provided patch to Google App Engine Python SDK version 1.5.4 or later, which properly implements sandbox restrictions for the os module access. Organizations should also implement comprehensive security monitoring for the _ah/admin/interactive/execute endpoint and establish strict access controls for development environments. The vulnerability aligns with CWE-250, which addresses execution of unknown code or commands, and represents a specific implementation of the broader category of sandbox escape techniques that fall under ATT&CK technique T1059.001 for command and scripting interpreter. Security teams should conduct thorough code reviews of any custom administrative interfaces and ensure that all development environments properly enforce sandboxing policies, particularly when executing user-provided code within administrative contexts.