CVE-2012-5491 in Plone
Summary
by MITRE
z3c.form, as used in Plone before 4.2.3 and 4.3 before beta 1, allows remote attackers to obtain the default form field values by leveraging knowledge of the form location and the element id.
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Analysis
by VulDB Data Team • 03/13/2019
The vulnerability identified as CVE-2012-5491 represents a significant information disclosure flaw within the z3c.form library when integrated into Plone content management systems. This issue affects versions prior to 4.2.3 and 4.3 beta 1, creating a scenario where remote attackers can exploit predictable form field structures to extract default values that should remain confidential. The vulnerability stems from insufficient access controls and predictable data exposure mechanisms within the form processing framework, allowing malicious actors to gather sensitive information about form configurations through targeted requests.
The technical implementation of this vulnerability relies on the predictable nature of form element identification within the Plone ecosystem. Attackers can leverage their knowledge of form locations and element IDs to construct specific requests that bypass normal access controls. This flaw operates at the application layer, specifically targeting the form rendering and processing components that handle default field values. The vulnerability is classified under CWE-200, which addresses improper exposure of sensitive information, and aligns with ATT&CK technique T1213.002 for data from information repositories. The predictable element ID structures and form location patterns create a pathway for attackers to systematically gather default form configurations.
The operational impact of this vulnerability extends beyond simple information disclosure, as default form field values may contain sensitive configuration data, system identifiers, or implementation details that could aid in subsequent attacks. An attacker who successfully exploits this vulnerability gains intelligence about the underlying system architecture, potentially enabling more sophisticated attacks such as form-based injection attempts or targeted exploitation of other system components. The exposure of default values could reveal internal data structures, field naming conventions, or configuration parameters that reduce the overall security posture of the affected Plone installations. This vulnerability particularly affects organizations relying on Plone for content management, where the exposure of form field defaults could provide adversaries with valuable reconnaissance data.
Mitigation strategies for CVE-2012-5491 focus on implementing proper access controls and input validation within the form processing components. Organizations should upgrade to Plone versions 4.2.3 or later, which include patches addressing the information disclosure vulnerability. Additional defensive measures include implementing proper authentication checks for form field access, randomizing element IDs where possible, and ensuring that default form values are not exposed through predictable pathways. Security configurations should enforce strict access controls for form processing endpoints, and organizations should conduct regular security assessments of their form handling mechanisms. The remediation process should also involve reviewing and updating form field access controls to prevent unauthorized exposure of system configuration data, aligning with security best practices outlined in the OWASP Top Ten and NIST cybersecurity frameworks.