CVE-2016-6555 in OpenNMS
Summary
by MITRE • 09/25/2021
OpenNMS version 18.0.1 and prior are vulnerable to a stored XSS issue due to insufficient filtering of SNMP trap supplied data. By creating a malicious SNMP trap, an attacker can store an XSS payload which will trigger when a user of the web UI views the events list page. This issue was fixed in version 18.0.2, released on September 20, 2016.
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Analysis
by VulDB Data Team • 10/02/2021
The vulnerability identified as CVE-2016-6555 represents a critical stored cross-site scripting flaw within OpenNMS versions 18.0.1 and earlier. This security weakness stems from inadequate input validation mechanisms within the SNMP trap processing functionality of the network monitoring platform. The flaw allows malicious actors to inject persistent XSS payloads through specially crafted SNMP trap data that gets stored within the system's event database. When unsuspecting administrators or users navigate to the events list page in the web interface, the malicious script executes within their browser context, potentially leading to unauthorized actions or data exfiltration.
The technical implementation of this vulnerability occurs at the data ingestion layer where SNMP trap information is processed and stored without proper sanitization of user-supplied input. This type of flaw falls under CWE-79 which specifically addresses cross-site scripting vulnerabilities, and more precisely maps to CWE-939 which deals with insufficient input filtering in web applications. The vulnerability exploits the trust relationship between the system and its users by leveraging legitimate SNMP trap functionality to deliver malicious payloads. Attackers can construct SNMP traps containing malicious JavaScript code that gets persisted in the OpenNMS database, making the payload execute every time the affected page is loaded.
The operational impact of CVE-2016-6555 extends beyond simple script execution, as it can enable attackers to perform session hijacking, steal cookies, redirect users to malicious sites, or even execute arbitrary commands within the victim's browser context. This is particularly concerning in enterprise environments where OpenNMS is used for critical network monitoring, as the attackers could potentially gain access to sensitive network information or manipulate monitoring data. The vulnerability affects the web-based user interface components of OpenNMS, specifically the events listing functionality, making it a prime target for exploitation. According to ATT&CK framework, this vulnerability maps to T1059.007 for script injection and T1566 for social engineering through malicious payloads, as the attack requires user interaction to trigger the XSS payload execution.
The remediation for this vulnerability required the implementation of proper input sanitization and output encoding mechanisms within the SNMP trap processing pipeline. OpenNMS version 18.0.2 addressed the issue by introducing comprehensive filtering of SNMP trap data before storage, ensuring that any potentially malicious content is properly escaped or removed. Organizations should implement immediate patching of affected systems to prevent exploitation, while also considering network segmentation and monitoring for unusual SNMP traffic patterns. The fix demonstrates the importance of input validation at all levels of application processing, particularly for data that originates from external sources and will be rendered in web contexts. Security teams should also review other input handling mechanisms within the OpenNMS platform to ensure similar vulnerabilities are not present in related components.