CVE-2021-21800 in R-SeeNet
Summary
by MITRE • 07/16/2021
Cross-site scripting vulnerabilities exist in the ssh_form.php script functionality of Advantech R-SeeNet v 2.4.12 (20.10.2020). If a user visits a specially crafted URL, it can lead to arbitrary JavaScript code execution in the context of the targeted user’s browser. An attacker can provide a crafted URL to trigger this vulnerability.
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Analysis
by VulDB Data Team • 07/19/2021
The vulnerability identified as CVE-2021-21800 represents a critical cross-site scripting flaw within the Advantech R-SeeNet version 2.4.12 web interface. This security weakness specifically affects the ssh_form.php script component that handles secure shell connection configurations within the network management platform. The vulnerability stems from inadequate input validation and output encoding mechanisms that fail to properly sanitize user-supplied data before rendering it within the web application's response. The affected system processes user-provided parameters without sufficient sanitization, creating an environment where malicious input can be interpreted as executable JavaScript code rather than benign data.
The technical exploitation of this vulnerability occurs through a carefully crafted URL that contains malicious JavaScript payloads within its parameters. When an unsuspecting user navigates to this specially constructed link, the web application processes the malformed input through the ssh_form.php script without proper validation. The vulnerability operates under CWE-79 which classifies it as a Cross-Site Scripting attack, specifically targeting the application's failure to properly encode output data. The flaw allows attackers to inject arbitrary JavaScript code that executes within the context of the victim's browser session, potentially compromising the user's authentication state and enabling further attacks.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with persistent access to the targeted user's browser session. This can lead to session hijacking, credential theft, and unauthorized access to network management functions that require elevated privileges. The attack vector is particularly dangerous because it requires minimal user interaction beyond visiting a malicious link, making it susceptible to phishing campaigns and social engineering attacks. The vulnerability affects the entire R-SeeNet platform's web interface, potentially compromising multiple administrative functions and network monitoring capabilities. Attackers could leverage this weakness to establish persistent backdoors, modify network configurations, or exfiltrate sensitive operational data.
Mitigation strategies should focus on immediate input validation and output encoding improvements within the ssh_form.php script. The recommended approach involves implementing comprehensive parameter sanitization that filters out potentially malicious input patterns before processing user data. Security patches should enforce strict content type validation and implement proper HTML encoding for all dynamic content generated by the application. Organizations should also consider implementing content security policies to prevent unauthorized script execution and establish network monitoring to detect anomalous traffic patterns associated with exploitation attempts. The vulnerability aligns with ATT&CK technique T1566 which covers social engineering tactics, and T1059 which addresses command and script injection methods. Regular security updates and penetration testing should be implemented to prevent similar vulnerabilities from emerging in other components of the R-SeeNet platform.