CVE-2017-5258 in ePMP
Summary
by MITRE
In version 3.5 and prior of Cambium Networks ePMP firmware, an attacker who knows or can guess the RW community string can provide a URL for a configuration file over SNMP with XSS strings in certain SNMP OIDs, serve it via HTTP, and the affected device will perform a configuration restore using the attacker's supplied config file, including the inserted XSS strings.
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Analysis
by VulDB Data Team • 12/17/2019
The vulnerability identified as CVE-2017-5258 represents a critical security flaw in Cambium Networks ePMP firmware versions 3.5 and earlier, demonstrating a dangerous combination of insecure configuration management and cross-site scripting exploitation. This vulnerability exists within the Simple Network Management Protocol implementation of the affected devices, specifically allowing unauthorized attackers to manipulate the configuration restoration process through carefully crafted SNMP OID values. The flaw stems from insufficient input validation and sanitization within the SNMP configuration handling mechanism, creating a pathway for attackers to inject malicious payloads that persist through device configuration updates.
The technical exploitation of this vulnerability requires an attacker to possess knowledge of or be able to guess the read-write community string, which serves as the authentication mechanism for SNMP operations. Once obtained, the attacker can craft malicious SNMP requests containing XSS payloads within specific OID values that control configuration file retrieval. When the device processes these requests and attempts to restore configuration from the supplied URL, it inadvertently executes the injected JavaScript code during the configuration parsing phase. This occurs because the firmware fails to properly sanitize or validate the content of configuration files retrieved via HTTP, allowing malicious scripts to be embedded directly into the device's operational environment. The vulnerability operates at the intersection of network management protocols and web-based configuration interfaces, creating a unique attack surface that combines SNMP-based remote command execution with web-based cross-site scripting capabilities.
The operational impact of this vulnerability extends far beyond simple script injection, as it enables attackers to gain persistent access to network infrastructure devices that are typically considered secure within corporate environments. Device administrators who rely on SNMP for network monitoring and management may unknowingly facilitate attacks by using default or predictable community strings, which are common practices in many network deployments. The configuration restoration process becomes a vector for code execution, potentially allowing attackers to establish backdoors, modify network policies, or redirect traffic through compromised devices. This vulnerability particularly affects wireless network infrastructure deployments where Cambium ePMP devices are commonly used, potentially enabling attackers to compromise entire wireless networks by targeting a single vulnerable device within the infrastructure.
Mitigation strategies for CVE-2017-5258 must address both the immediate exposure and underlying architectural weaknesses that enable the attack. Organizations should immediately update to firmware versions that resolve this vulnerability, as Cambium has released patches specifically addressing the insecure configuration handling and input validation issues. Network segmentation and access control measures should be implemented to limit SNMP access to trusted management stations only, while strong community string policies must be enforced using complex, non-default values that are regularly rotated. The implementation of network monitoring solutions capable of detecting anomalous SNMP traffic patterns and configuration file transfers can provide early warning of attempted exploitation. Additionally, security awareness training for network administrators should emphasize the importance of proper SNMP configuration management and the risks associated with predictable community strings. This vulnerability aligns with CWE-79 Cross-site Scripting and CWE-20 Improper Input Validation, and maps to ATT&CK techniques involving configuration manipulation and credential access through network protocols. Organizations should also consider implementing network access control lists and firewall rules that restrict HTTP access from SNMP management interfaces to prevent the exploitation of this vulnerability through HTTP-based configuration file delivery mechanisms.