CVE-2012-5487 in Plone
Summary
by MITRE
The sandbox whitelisting function (allowmodule.py) in Plone before 4.2.3 and 4.3 before beta 1 allows remote authenticated users with certain privileges to bypass the Python sandbox restriction and execute arbitrary Python code via vectors related to importing.
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Analysis
by VulDB Data Team • 06/06/2017
The vulnerability identified as CVE-2012-5487 represents a critical sandbox escape flaw within the Plone content management system that undermines fundamental security controls designed to isolate user code execution. This vulnerability specifically targets the allowmodule.py component responsible for implementing whitelisting functionality within Plone's Python sandbox environment. The flaw exists in Plone versions prior to 4.2.3 and 4.3 beta 1, making a substantial portion of the Plone user base susceptible to exploitation. The vulnerability's severity is amplified by the fact that it requires only authenticated access with specific privileges rather than administrative credentials, making it particularly dangerous in environments where multiple users have varying levels of access. The sandbox mechanism was intended to prevent malicious code execution by restricting which Python modules could be imported or executed, but this weakness creates a pathway for attackers to circumvent these protections.
The technical exploitation of this vulnerability occurs through carefully crafted import operations that manipulate the whitelisting logic to bypass security restrictions. Attackers with authenticated access can leverage the allowmodule.py function to import modules that should normally be restricted, effectively breaking out of the sandboxed execution environment. This occurs because the whitelisting implementation fails to properly validate or sanitize import requests, allowing malicious users to specify module paths or import sequences that circumvent the intended restrictions. The vulnerability falls under the CWE-254 category of security features that do not properly protect against privilege escalation, specifically targeting the improper restriction of operations within a restricted environment. The attack vector involves leveraging legitimate import mechanisms while exploiting implementation gaps in the module validation process, enabling code execution that could range from data exfiltration to complete system compromise.
The operational impact of this vulnerability extends far beyond simple code execution, as it fundamentally compromises the security model of Plone installations that rely on sandboxing for user isolation. Organizations running affected Plone versions face significant risks including unauthorized data access, potential system takeover, and exposure of sensitive information stored within the CMS. The vulnerability can be particularly devastating in multi-tenant environments where different users share the same Plone instance, as a single compromised account could potentially provide access to code execution capabilities across the entire system. Attackers could leverage this vulnerability to install backdoors, modify content, steal credentials, or perform other malicious activities that would otherwise be prevented by the sandbox restrictions. The impact is particularly severe because the vulnerability affects the core security architecture of the platform, undermining trust in the system's ability to isolate user activities and maintain data integrity.
Organizations should immediately implement mitigations including upgrading to Plone versions 4.2.3 or later, or 4.3 beta 1 and subsequent releases that contain the patched allowmodule.py implementation. The upgrade process should include thorough testing to ensure that legitimate functionality remains intact while addressing the security gap. Additional protective measures include implementing network segmentation to limit access to Plone systems, restricting user privileges to the minimum necessary for their roles, and monitoring for suspicious import activities. Security teams should also consider implementing intrusion detection systems that can identify anomalous import patterns consistent with exploitation attempts. The remediation process should follow established security practices including vulnerability assessment, impact analysis, and rollback procedures to maintain system availability during the patching process. Organizations should also review their access control policies and ensure that only authorized personnel have the privileges necessary to perform operations that could trigger the vulnerability, aligning with defense-in-depth strategies recommended by cybersecurity frameworks such as those published by NIST and ISO 27001.