CVE-2020-8143 in Adserver
Summary
by MITRE
An Open Redirect vulnerability was discovered in Revive Adserver version < 5.0.5 and reported by HackerOne user hoangn144. A remote attacker could trick logged-in users to open a specifically crafted link and have them redirected to any destination.The CSRF protection of the “/www/admin/*-modify.php� could be skipped if no meaningful parameter was sent. No action was performed, but the user was still redirected to the target page, specified via the “returnurl� GET parameter.
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Analysis
by VulDB Data Team • 05/13/2024
The CVE-2020-8143 vulnerability represents a critical open redirect flaw in Revive Adserver versions prior to 5.0.5, demonstrating how seemingly minor implementation gaps can create significant security risks for web applications. This vulnerability specifically affects the administrative interface of the ad server software, where the application fails to properly validate redirect URLs before executing redirects. The flaw allows attackers to craft malicious links that appear legitimate to users but will redirect them to arbitrary destinations, potentially enabling phishing attacks or credential theft. The vulnerability was identified through responsible disclosure by HackerOne user hoangn144, highlighting the importance of community-driven security research in identifying application weaknesses.
The technical implementation of this vulnerability stems from inadequate input validation within the administrative modification pages of Revive Adserver. When users navigate to pages such as /www/admin/*-modify.php, the application accepts a returnurl GET parameter without proper sanitization or validation of the target URL. This parameter is used to determine where users should be redirected after performing administrative actions. The flaw exists because the system does not verify whether the provided redirect URL is within the application's domain or if it points to a trusted location. This allows attackers to manipulate the returnurl parameter to point to malicious domains, effectively bypassing the application's intended navigation flow. The vulnerability operates under CWE-601, which specifically addresses open redirect vulnerabilities where applications redirect users to untrusted destinations without proper validation.
The operational impact of CVE-2020-8143 extends beyond simple redirection attacks, creating potential vectors for more sophisticated social engineering campaigns. When logged-in administrators click on maliciously crafted links, they are automatically redirected to attacker-controlled domains, potentially exposing sensitive administrative credentials or enabling further exploitation. The vulnerability is particularly dangerous because it affects the administrative interface, which typically contains sensitive configuration options and user management capabilities. Attackers could leverage this flaw to redirect administrators to phishing pages that mimic legitimate administrative interfaces, potentially capturing login credentials or executing additional attacks. The vulnerability also aligns with ATT&CK technique T1566, which covers social engineering through spearphishing, as it enables attackers to manipulate user navigation to malicious sites. The fact that CSRF protection can be bypassed without performing any actual administrative actions makes this vulnerability particularly concerning, as it can be exploited for reconnaissance or credential harvesting without alerting system administrators.
Organizations using Revive Adserver versions prior to 5.0.5 should immediately implement mitigations to address this vulnerability, with the most effective solution being the upgrade to version 5.0.5 or later where the issue has been resolved. The primary technical mitigation involves implementing strict URL validation for all redirect parameters, ensuring that any returnurl parameter is either validated against a whitelist of trusted domains or properly sanitized to prevent protocol-relative URLs. Organizations should also consider implementing additional security measures such as Content Security Policy headers to prevent unauthorized redirects and monitoring for suspicious redirect patterns in web application logs. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in web application security, where administrative interfaces should never blindly trust user-provided redirect parameters. Security teams should also conduct regular vulnerability assessments of their web applications to identify similar issues in other components, as open redirect vulnerabilities are commonly found in web frameworks and applications where proper input validation is not consistently implemented.