CVE-2017-6932 in Drupal
Summary
by MITRE
Drupal core 7.x versions before 7.57 has an external link injection vulnerability when the language switcher block is used. A similar vulnerability exists in various custom and contributed modules. This vulnerability could allow an attacker to trick users into unwillingly navigating to an external site.
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2017-6932 represents a critical external link injection flaw within Drupal core 7.x versions prior to 7.57, specifically when utilizing the language switcher block functionality. This security weakness stems from inadequate validation of external URLs within the language switching mechanism, creating an avenue for malicious actors to manipulate user navigation through crafted link parameters. The vulnerability operates by exploiting the way Drupal processes language switcher block configurations, where external URLs are not properly sanitized before being rendered to end users, thereby enabling attackers to inject arbitrary external links that appear legitimate within the context of the website's navigation interface.
The technical implementation of this vulnerability aligns with CWE-601, which categorizes open redirect vulnerabilities where applications redirect users to untrusted domains without proper validation. Attackers can leverage this flaw by crafting malicious URLs that include encoded external links within the language switcher block parameters, causing the website to display navigation options that redirect users to attacker-controlled domains. The vulnerability's exploitation typically involves manipulating URL parameters or form submissions that feed into the language switcher block rendering process, where the system fails to validate that external links originate from trusted sources or properly encode the URLs before presentation.
From an operational impact perspective, this vulnerability poses significant risks to user trust and security awareness, as it enables social engineering attacks where users are unknowingly directed to malicious websites that may attempt to harvest credentials, install malware, or conduct phishing operations. The attack surface extends beyond Drupal core to include numerous custom and contributed modules that implement similar language switching functionality, amplifying the potential impact across the Drupal ecosystem. Security researchers have noted that the vulnerability's exploitation is relatively straightforward, requiring minimal technical expertise to craft effective attacks, making it particularly dangerous in environments where users frequently interact with language switcher interfaces.
Organizations affected by this vulnerability should prioritize immediate remediation through Drupal core updates to version 7.57 or later, which includes patches addressing the external link validation issues within language switcher blocks. Additionally, security administrators should implement comprehensive URL validation policies for all language switcher configurations and conduct thorough code reviews of custom modules to identify similar implementation flaws. Network monitoring should be enhanced to detect suspicious redirect patterns, while user education programs should emphasize the importance of verifying destination URLs before clicking navigation links. The ATT&CK framework categorizes this vulnerability under T1566, which covers "Phishing" techniques, as the primary attack vector involves deceiving users into navigating to malicious external sites through seemingly legitimate website navigation elements. Organizations should also consider implementing web application firewalls and content security policies to provide additional layers of protection against exploitation attempts.