CVE-2017-5524 in Plone
Summary
by MITRE
Plone 4.x through 4.3.11 and 5.x through 5.0.6 allow remote attackers to bypass a sandbox protection mechanism and obtain sensitive information by leveraging the Python string format method.
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Analysis
by VulDB Data Team • 09/13/2020
The vulnerability identified as CVE-2017-5524 represents a critical sandbox bypass issue affecting Plone content management systems across multiple versions including 4.x through 4.3.11 and 5.x through 5.0.6. This flaw specifically targets the Python string format method implementation within the Plone framework, allowing remote attackers to circumvent intended security restrictions that are designed to prevent unauthorized access to sensitive system information. The vulnerability stems from insufficient input validation and improper handling of string formatting operations that could potentially expose internal system details to malicious actors without authentication.
The technical execution of this vulnerability relies on the manipulation of Python string formatting capabilities within the Plone environment. When the system processes user-supplied input through string format methods, it fails to properly sanitize or validate the formatting parameters, creating an opportunity for attackers to inject malicious format specifiers. This weakness enables adversaries to craft specific input sequences that can trigger the Python interpreter to reveal internal object references, memory addresses, or other sensitive information that should normally be protected by the sandbox mechanism. The exploitation occurs at the core level where Python's string formatting functionality interacts with Plone's security controls, effectively neutralizing the intended isolation between user input and system internals.
From an operational impact perspective, this vulnerability poses significant risks to organizations relying on Plone for content management and web application hosting. The bypass of sandbox protections means that attackers can potentially access sensitive data, system configurations, and internal application structures that could facilitate further exploitation attempts. The remote nature of the attack vector eliminates the need for physical access or local system compromise, making the vulnerability particularly dangerous for publicly accessible Plone installations. Security researchers have categorized this issue under CWE-20, which describes improper input validation, and the attack pattern aligns with techniques described in the ATT&CK framework under privilege escalation and information gathering tactics. Organizations may face data breaches, system compromise, and regulatory compliance violations if this vulnerability remains unaddressed.
The recommended mitigations for CVE-2017-5524 include immediate application of official patches released by the Plone community and implementation of comprehensive input validation measures. System administrators should ensure all Plone installations are updated to versions that contain the necessary security fixes, typically involving enhanced sanitization of string formatting operations and stricter validation of user input before processing. Additional defensive measures include implementing web application firewalls that can detect and block suspicious string formatting patterns, conducting regular security assessments of Plone applications, and establishing monitoring procedures to identify anomalous access patterns that may indicate exploitation attempts. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts, while maintaining regular vulnerability scanning to identify similar issues in other components of their web application infrastructure.