CVE-2016-3171 in Drupal
Summary
by MITRE
Drupal 6.x before 6.38, when used with PHP before 5.4.45, 5.5.x before 5.5.29, or 5.6.x before 5.6.13, might allow remote attackers to execute arbitrary code via vectors related to session data truncation.
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Analysis
by VulDB Data Team • 10/05/2018
This vulnerability affects Drupal 6.x versions prior to 6.38 when running on specific PHP versions that lack proper session data handling mechanisms. The issue stems from a critical flaw in how session data is processed and truncated within the application's session management system. When Drupal operates with PHP versions before the specified patches, it becomes susceptible to a remote code execution attack through manipulation of session data. The vulnerability specifically exploits the way PHP handles session data truncation, which creates a condition where attacker-controlled data can be injected into session storage and subsequently executed as code.
The technical root cause of this vulnerability lies in the improper handling of session data boundaries within the PHP runtime environment. When session data exceeds certain size thresholds, the truncation process fails to properly sanitize or validate the data, allowing malicious input to persist in the session storage. This creates a persistent injection vector that can be leveraged by remote attackers to execute arbitrary commands on the affected system. The vulnerability is particularly dangerous because it operates at the session management layer, which is fundamental to web application security and user authentication processes.
From an operational impact perspective, this vulnerability represents a severe threat to Drupal 6.x installations that have not been updated to the patched versions. Attackers can exploit this weakness to gain full control over affected systems, potentially leading to complete compromise of the web application and underlying infrastructure. The remote nature of the attack means that exploitation can occur from anywhere on the internet without requiring physical access or prior authentication. This vulnerability directly impacts the integrity and confidentiality of data stored within Drupal systems, as well as the availability of the web services provided by these applications. Organizations running vulnerable versions face significant risk of data breaches, system compromise, and potential regulatory compliance violations.
Security mitigations for this vulnerability include immediate upgrade of Drupal 6.x installations to version 6.38 or later, along with updating the underlying PHP runtime to versions that include proper session data handling. System administrators should also implement network-level protections such as firewalls and intrusion detection systems to monitor for suspicious session-related traffic patterns. Additionally, organizations should conduct thorough security assessments of their Drupal installations to identify any potential exploitation attempts and implement proper input validation and sanitization measures. This vulnerability aligns with CWE-122, which describes buffer overflow vulnerabilities in session management, and maps to ATT&CK technique T1059.007 for remote code execution through web application vulnerabilities. Organizations should also consider implementing web application firewalls and monitoring for anomalous session data patterns that could indicate exploitation attempts.