CVE-2013-4446 in context
Summary
by MITRE
The _json_decode function in plugins/context_reaction_block.inc in the Context module 6.x-2.x before 6.x-3.2 and 7.x-3.x before 7.x-3.0 for Drupal, when using a version of PHP that does not support the json_decode function, allows remote attackers to execute arbitrary PHP code via unspecified vectors related to Ajax operations, possibly involving eval injection.
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Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2013-4446 represents a critical remote code execution flaw within the Context module for Drupal platforms. This issue specifically affects versions 6.x-2.x prior to 6.x-3.2 and 7.x-3.x prior to 7.x-3.0, creating a dangerous attack surface when Drupal installations operate with PHP versions lacking native json_decode support. The vulnerability stems from the _json_decode function implementation in plugins/context_reaction_block.inc, which handles Ajax operations within the Drupal framework.
The technical exploitation mechanism involves improper handling of JSON data processing within the Context module's reaction block functionality. When PHP environments lack native json_decode capabilities, the module falls back to custom implementation that inadvertently introduces code execution vulnerabilities. Attackers can leverage this weakness through Ajax requests that contain maliciously crafted data, potentially leading to eval injection attacks where arbitrary PHP code gets executed on the target server. This represents a classic server-side code injection vulnerability that bypasses normal input validation mechanisms.
The operational impact of this vulnerability extends beyond simple data compromise, as successful exploitation allows attackers to execute arbitrary commands with the privileges of the web server process. This can result in complete system compromise, data exfiltration, and potential lateral movement within network environments where Drupal installations reside. The vulnerability affects organizations running Drupal 6 and 7 platforms, particularly those with legacy PHP installations that don't support modern JSON processing functions. The attack vector through Ajax operations makes this vulnerability particularly dangerous as it can be triggered through normal user interactions with web forms and dynamic content loading features.
Security professionals should prioritize patching affected Drupal installations immediately, upgrading to Context module versions 6.x-3.2 and 7.x-3.0 or later. Organizations should also implement network-level protections such as web application firewalls to monitor and block suspicious Ajax requests containing potentially malicious JSON data. The vulnerability aligns with CWE-94, which covers "Improper Control of Generation of Code ('Code Injection')" and relates to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Python" where the attack chain may involve code execution through web interfaces. Additional mitigations include restricting Ajax endpoint access through proper authentication mechanisms and implementing strict input validation for all JSON data processing within Drupal modules.
This vulnerability demonstrates the critical importance of proper JSON handling in web applications and the dangers of fallback code implementations that bypass standard security controls. The issue highlights how seemingly minor functionality gaps in PHP versions can create significant security risks when combined with custom module implementations. Organizations should conduct comprehensive security assessments of their Drupal installations to identify other potential modules with similar vulnerabilities and establish robust patch management processes to prevent such issues from occurring in the future.