CVE-2017-6539 in webpagetest
Summary
by MITRE
Multiple Cross-Site Scripting (XSS) issues were discovered in webpagetest 3.0. The vulnerabilities exist due to insufficient filtration of user-supplied data (benchmark, time) passed to the webpagetest-master/www/benchmarks/delta.php URL. An attacker could execute arbitrary HTML and script code in a browser in the context of the vulnerable website.
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Analysis
by VulDB Data Team • 09/05/2020
The vulnerability identified as CVE-2017-6539 represents a critical cross-site scripting flaw in the webpagetest 3.0 application, specifically within the benchmark functionality. This issue stems from inadequate input validation and sanitization mechanisms that fail to properly filter user-supplied data before processing. The vulnerability manifests in the webpagetest-master/www/benchmarks/delta.php endpoint where benchmark and time parameters are directly incorporated into the web application's response without proper security measures. The flaw allows malicious actors to inject malicious scripts that execute within the context of the victim's browser session, effectively compromising the integrity of the web application and potentially leading to unauthorized access or data exfiltration.
The technical nature of this vulnerability aligns with CWE-79 which specifically addresses cross-site scripting vulnerabilities arising from insufficient input validation and output encoding. This particular implementation flaw demonstrates a classic case of reflected XSS where user-controllable parameters are echoed back to the browser without proper sanitization. The attack vector is straightforward yet dangerous as it requires minimal privileges to exploit, making it particularly attractive to threat actors. The vulnerability exists because the application fails to implement proper HTML escaping or encoding for user-supplied input, allowing attackers to inject script tags or other malicious code that executes when the page renders. This type of vulnerability is classified under the ATT&CK technique T1203 - Exploitation for Client Execution, which describes how adversaries use web-based attacks to execute malicious code in victim browsers.
The operational impact of this vulnerability extends beyond simple script execution, as it can lead to session hijacking, credential theft, and potential full system compromise. When an attacker successfully injects malicious code through the vulnerable delta.php endpoint, they can manipulate the web application's behavior and potentially access sensitive data or perform unauthorized actions on behalf of authenticated users. The reflected nature of this XSS vulnerability means that the malicious payload must be delivered to the victim through social engineering or by enticing them to click a malicious link containing the exploit. This creates a significant risk for organizations using webpagetest 3.0 for performance monitoring, as the tool may be exposed to untrusted users who could leverage this vulnerability to compromise the testing environment. The vulnerability affects not only the immediate web application but also any associated systems that rely on the test results or the testing infrastructure itself.
Mitigation strategies for CVE-2017-6539 should focus on implementing comprehensive input validation and output encoding mechanisms. Organizations should immediately patch the webpagetest 3.0 application to the latest version that addresses this vulnerability, as the developers have likely released a fix for the insufficient filtration issue. In the interim, administrators should implement proper HTML escaping for all user-supplied data before rendering it in web pages, particularly for parameters passed to the delta.php endpoint. Additional protective measures include implementing Content Security Policy (CSP) headers to limit script execution and using web application firewalls to detect and block malicious payloads. The vulnerability also underscores the importance of regular security assessments and input validation testing to prevent similar issues in other web applications. Organizations should conduct thorough code reviews focusing on user input handling and ensure that all dynamic content is properly sanitized before being incorporated into web responses, thereby reducing the attack surface and protecting against similar reflected XSS vulnerabilities.