CVE-2021-25810 in Mercury X18G
Summary
by MITRE • 04/29/2021
Cross site Scripting (XSS) vulnerability in MERCUSYS Mercury X18G 1.0.5 devices, via crafted values to the 'src_dport_start', 'src_dport_end', and 'dest_port' parameters.
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Analysis
by VulDB Data Team • 05/03/2021
The CVE-2021-25810 vulnerability represents a critical cross site scripting flaw discovered in MERCUSYS Mercury X18G 1.0.5 network devices, exposing users to significant security risks through improper input validation mechanisms. This vulnerability resides within the device's web-based management interface, where the system fails to adequately sanitize user-supplied parameters during configuration operations. The affected parameters include 'src_dport_start', 'src_dport_end', and 'dest_port' which are utilized in port filtering and firewall configuration settings, making them particularly dangerous as they handle network traffic control data. The vulnerability stems from the device's failure to implement proper output encoding or input validation when processing these specific parameters, creating an avenue for malicious actors to inject arbitrary script code into the device's web interface.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious input values for the specified parameters and submits them through the device's web management interface. When the device processes these crafted values without proper sanitization, the malicious scripts become embedded within the web page responses and execute in the context of the victim's browser session. This allows attackers to perform actions such as stealing session cookies, modifying device configurations, or redirecting users to malicious sites. The vulnerability operates under CWE-79 which specifically addresses cross site scripting flaws, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as the attack chain involves executing malicious code through web-based interfaces. The device's failure to implement proper input validation creates a persistent security gap that can be exploited by attackers with minimal privileges, as the web interface typically requires only basic authentication credentials.
The operational impact of this vulnerability extends beyond simple script execution, as it fundamentally compromises the integrity and confidentiality of the network device's management interface. Attackers can leverage this vulnerability to gain unauthorized access to device configuration settings, potentially leading to complete network compromise through altered firewall rules, modified routing configurations, or unauthorized access point modifications. The vulnerability affects the device's ability to maintain secure communication channels and can enable attackers to establish persistent access points within the network infrastructure. Network administrators may find their security monitoring systems compromised as malicious scripts can manipulate the device's logging and reporting capabilities, masking the actual attack activity. The vulnerability also poses risks to downstream systems as attackers can manipulate port filtering rules to create backdoors or redirect network traffic through malicious endpoints.
Mitigation strategies for CVE-2021-25810 should prioritize immediate firmware updates from MERCUSYS to address the identified input validation flaws. Organizations should implement network segmentation to limit access to the device's management interface to authorized personnel only, utilizing network access control lists and firewall rules to restrict communication to only necessary IP addresses. Additional defensive measures include implementing web application firewalls that can detect and block malicious script injection attempts, conducting regular security assessments of network device configurations, and establishing monitoring protocols to detect unusual parameter values in device logs. Network administrators should disable unnecessary web management interfaces when not actively required, and implement multi-factor authentication for device access. The vulnerability demonstrates the importance of input validation and output encoding practices, aligning with security best practices outlined in NIST SP 800-160 and OWASP Top 10 categories for injection flaws, emphasizing the need for comprehensive security controls that address both application-level and network-level threats.