CVE-2019-3927 in AM-100
Summary
by MITRE
Crestron AM-100 with firmware 1.6.0.2 and AM-101 with firmware 2.7.0.2 anyone can change the administrator and moderator passwords via the iso.3.6.1.4.1.3212.100.3.2.8.1 and iso.3.6.1.4.1.3212.100.3.2.8.2 OIDs. A remote, unauthenticated attacker can use this vulnerability to change the admin or moderator user's password and gain access to restricted areas on the HTTP interface.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/11/2023
The CVE-2019-3927 vulnerability affects Crestron AM-100 and AM-101 devices running specific firmware versions, presenting a critical security flaw in the device's management interface. This vulnerability stems from improper access controls within the device's Simple Network Management Protocol (SNMP) implementation, specifically within the Object Identifier (OID) structure used for password management. The affected OIDs iso.3.6.1.4.1.3212.100.3.2.8.1 and iso.3.6.1.4.1.3212.100.3.2.8.2 are designed to allow password modification but lack adequate authentication mechanisms, enabling unauthorized users to manipulate administrative credentials.
The technical flaw manifests through the absence of proper authentication checks when accessing these specific SNMP OIDs, which are part of the Crestron proprietary management framework. This vulnerability aligns with CWE-287, which addresses improper authentication issues, and represents a significant weakness in the device's privilege management system. The flaw allows attackers to remotely modify administrator and moderator passwords without requiring any credentials, effectively bypassing the device's security model entirely. The vulnerability exists in the device's SNMP implementation where the OID access controls are not properly enforced, creating a path for unauthorized password modification through the network management interface.
The operational impact of this vulnerability is severe as it provides complete administrative control over affected devices, enabling attackers to gain unrestricted access to restricted areas of the HTTP interface. Once exploited, an attacker can modify user accounts, access sensitive configuration data, and potentially escalate privileges to gain full control of the network management system. This vulnerability directly maps to ATT&CK technique T1210, which covers exploitation of remote services, and T1078, which addresses valid accounts usage. The remote, unauthenticated nature of the attack means that any network-connected device can be compromised without prior access or credentials, making it particularly dangerous in enterprise environments where these devices often serve as critical infrastructure components.
Mitigation strategies should include immediate firmware updates from Crestron to address the authentication flaw, network segmentation to isolate these devices from critical systems, and implementation of SNMP access control lists to restrict OID access. Organizations should also monitor network traffic for suspicious SNMP activity and implement network access controls to prevent unauthorized access to management ports. The vulnerability demonstrates the importance of proper authentication implementation in network management protocols and highlights the need for regular security assessments of industrial control systems to identify similar weaknesses in proprietary implementations.