CVE-2017-9071 in Revolution
Summary
by MITRE
In MODX Revolution before 2.5.7, an attacker might be able to trigger XSS by injecting a payload into the HTTP Host header of a request. This is exploitable only in conjunction with other issues such as Cache Poisoning.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability described in CVE-2017-9071 affects MODX Revolution content management systems prior to version 2.5.7, representing a cross-site scripting weakness that stems from improper handling of the HTTP Host header. This particular flaw demonstrates how seemingly innocuous header parameters can become attack vectors when not properly sanitized or validated within web applications. The vulnerability specifically manifests when an attacker injects malicious code into the Host header of HTTP requests, which then gets processed by the CMS without adequate input validation or output encoding measures.
The technical nature of this vulnerability aligns with CWE-79, which classifies cross-site scripting flaws as weaknesses that occur when an application includes untrusted data in a web page without proper validation or encoding. In MODX Revolution's case, the application fails to properly sanitize the Host header before using it in dynamic content generation, creating an environment where attacker-controlled input can be executed within the context of a victim's browser. This issue becomes particularly dangerous when combined with other vulnerabilities such as cache poisoning, as demonstrated in the original description, since attackers can leverage the Host header injection to manipulate cached content that may be served to multiple users simultaneously.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal sensitive cookies, redirect users to malicious sites, or even execute more sophisticated attacks through the exploitation of the compromised application context. When combined with cache poisoning techniques, the vulnerability becomes even more potent because the injected malicious code can persist in cached responses and affect numerous users over extended periods. This creates a scenario where a single injection point can compromise multiple users who access cached content, making the attack surface significantly larger than typical XSS vulnerabilities that only affect individual requests.
Security practitioners should note that this vulnerability highlights the importance of input validation at all levels of web application architecture, particularly in HTTP headers that are often overlooked during security assessments. The remediation approach for CVE-2017-9071 involves implementing proper header sanitization and validation mechanisms within MODX Revolution, ensuring that the Host header is properly encoded before being used in any dynamic content generation processes. Organizations should also consider implementing web application firewalls that can detect and block suspicious Host header patterns, while also ensuring that all MODX installations are updated to version 2.5.7 or later where this vulnerability has been addressed through proper input validation controls. The ATT&CK framework categorizes this type of vulnerability under T1203, which covers exploitation of web application vulnerabilities, and the remediation efforts should align with defensive techniques that focus on input validation and output encoding as primary mitigation strategies.