CVE-2012-5704 in Hotblocks
Summary
by MITRE
The Hotblocks module 6.x-1.x before 6.x-1.8 for Drupal allows remote authenticated users with the "administer hotblocks" permission to cause a denial of service (infinite loop and time out) via a block that references itself.
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Analysis
by VulDB Data Team • 02/23/2019
The vulnerability identified as CVE-2012-5704 affects the Hotblocks module version 6.x-1.x prior to 6.x-1.8 in the Drupal content management system. This security flaw represents a classic denial of service condition that can be exploited by authenticated users who possess the specific permission to administer hotblocks within the Drupal environment. The issue arises from insufficient input validation and recursive reference handling within the module's block processing logic, creating a scenario where maliciously crafted block configurations can trigger system instability.
The technical exploitation of this vulnerability occurs when an authenticated user with the "administer hotblocks" permission creates or modifies a block configuration that references itself either directly or indirectly through a chain of references. This self-referential block structure causes the module's processing routine to enter an infinite loop when attempting to resolve the block hierarchy during rendering or administrative operations. The infinite loop consumes excessive CPU resources and system time, ultimately leading to a service timeout that prevents legitimate users from accessing the affected functionality.
From an operational impact perspective, this vulnerability demonstrates a significant security risk within Drupal's module architecture where proper input sanitization and dependency resolution mechanisms are lacking. The flaw can be particularly dangerous in high-traffic environments where the denial of service condition could impact multiple users simultaneously, effectively rendering the hotblocks administrative functionality unusable. The vulnerability also highlights the importance of proper permission controls and input validation in web applications, as it requires only a specific administrative role to exploit rather than more privileged access levels.
The root cause of this vulnerability aligns with CWE-835, which describes the weakness of an infinite loop or infinite recursion in software systems. This weakness specifically manifests when a program fails to properly terminate iterative or recursive processes, often due to missing termination conditions or flawed logic in dependency resolution. The vulnerability also relates to ATT&CK technique T1499.004, which covers network denial of service through resource exhaustion, where the infinite loop serves as the mechanism to consume system resources and cause service unavailability.
Organizations should implement immediate mitigations including updating to the patched version 6.x-1.8 or later of the Hotblocks module, implementing additional input validation measures within their Drupal installations, and monitoring for suspicious block configurations that might indicate exploitation attempts. Security teams should also consider implementing rate limiting and resource monitoring to detect and prevent similar vulnerabilities from being exploited in other modules or components of their Drupal infrastructure. Regular security audits and dependency management practices are essential to prevent such issues from occurring in other third-party modules that may have similar recursive reference handling flaws.