CVE-2019-20459 in Expression Home XP255
Summary
by MITRE • 11/07/2024
An issue was discovered on Epson Expression Home XP255 20.08.FM10I8 devices. With the SNMPv1 public community, all values can be read, and with the epson community, all the changeable values can be written/updated, as demonstrated by permanently disabling the network card or changing the DNS servers.
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Analysis
by VulDB Data Team • 11/07/2024
This vulnerability exists in Epson Expression Home XP255 printers running firmware version 20.08.FM10I8 and represents a critical security flaw in the device's SNMP implementation. The issue stems from improper access control mechanisms within the Simple Network Management Protocol v1 configuration, where the default public community string provides unrestricted read access to all system parameters. Additionally, the epson community string grants write privileges to configurable system settings, creating a dangerous combination that allows attackers to manipulate critical network configurations. The vulnerability falls under CWE-284 Access Control Issues, specifically demonstrating inadequate privilege separation between read and write operations. From an operational perspective, this weakness enables adversaries to execute persistent network disruptions and maintain long-term access to the device through unauthorized modifications. The ability to permanently disable network interfaces represents a significant availability threat that could prevent legitimate users from accessing the device or its network services.
The technical exploitation of this vulnerability follows ATT&CK technique T1071.004 Application Layer Protocol DNS, as attackers can modify DNS server settings to redirect network traffic or prevent communication with legitimate services. Network administrators who rely on SNMP for device monitoring and management face particular risk since the public community string allows comprehensive system enumeration without authentication. The epson community string, while more restrictive in its scope, still enables modification of critical network parameters including IP addresses, gateway settings, and DNS configurations that could facilitate network infiltration or denial of service attacks. This vulnerability aligns with ATT&CK technique T1566 Impersonation, as attackers can effectively impersonate legitimate administrative functions through the SNMP interface. The lack of proper authentication checks and the exposure of sensitive system parameters creates a pathway for attackers to escalate privileges and maintain persistent access to the network infrastructure.
Mitigation strategies should begin with immediate configuration changes including disabling SNMPv1 support entirely and transitioning to SNMPv3 with strong authentication and encryption. Network segmentation should be implemented to isolate printer devices from critical network segments, reducing the attack surface for potential exploitation. Regular firmware updates must be enforced, as this vulnerability has been addressed in subsequent releases through proper access control implementation. Network monitoring should include SNMP traffic analysis to detect unauthorized access attempts and parameter modifications. The principle of least privilege must be applied by ensuring that only authorized personnel have access to the epson community string, and that community names are changed from default values. Organizations should implement network access control lists to restrict SNMP traffic to trusted management stations only. Additionally, regular security audits should verify that SNMP services are properly configured and that default community strings have been removed from all networked devices. The vulnerability demonstrates the importance of proper protocol configuration and the dangers of leaving default administrative credentials enabled in networked devices, as outlined in industry best practices for secure network device management.