CVE-2015-7256 in NWA1123-NI
Summary
by MITRE
ZyXEL NWA1100-N, NWA1100-NH, NWA1121-NI, NWA1123-AC, NWA1123-NI Access Points, P-660HN-51, P-663HN-51, VMG1312-B10A, VMG1312-B30A, VMG1312-B30B, VMG4380-B10A, VMG8324-B10A, VMG8924-B10A, VMG8924-B30A, VSG1435-B101 DSL CPEs, PMG5318-B20A GPON, SBG3300-N000, SBG3300-NB00, SBG3500-N000 Small Business Gateways, GS1900-8, GS1900-24 Switchs, and C1000Z, Q1000, FR1000Z, P8702N Project Models use non-unique X.509 certificates and SSH host keys.
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Analysis
by VulDB Data Team • 12/20/2024
The vulnerability described in CVE-2015-7256 represents a critical security flaw affecting numerous ZyXEL network devices including access points, DSL CPEs, small business gateways, switches, and project models. This issue stems from the manufacturer's failure to implement unique cryptographic identifiers across their product lineup, creating a widespread security risk that impacts thousands of devices deployed in both enterprise and small business environments. The flaw specifically affects the X.509 certificates and SSH host keys used by these devices, which are fundamental components for establishing secure communications and device authentication within network infrastructures.
The technical implementation of this vulnerability manifests through the use of identical or non-unique cryptographic certificates and keys across multiple device models and serial numbers. When devices share the same X.509 certificates and SSH host keys, attackers can exploit this weakness to perform man-in-the-middle attacks, impersonate legitimate devices, or conduct certificate-based authentication bypasses. This vulnerability directly maps to CWE-310 which addresses cryptographic issues, particularly those involving weak or predictable cryptographic keys. The shared certificates create a single point of failure where compromising one device effectively compromises the entire network segment that relies on these identical identifiers for secure communications.
The operational impact of this vulnerability extends far beyond simple network access issues, as it fundamentally undermines the trust model that secure network communications depend upon. Network administrators face significant challenges in maintaining security postures when devices within their infrastructure share identical cryptographic identifiers, making it extremely difficult to detect unauthorized access or device impersonation attempts. This weakness creates opportunities for attackers to establish persistent access points within networks, potentially leading to complete network compromise. The vulnerability affects a broad range of devices from wireless access points to core network infrastructure equipment, making it particularly dangerous in enterprise environments where multiple device types communicate with each other.
From an attack perspective, this vulnerability aligns with several ATT&CK framework techniques including T1021.004 (Remote Services: SSH) and T1552.001 (Unsecured Credentials: Credentials in Files) as attackers can leverage the shared keys to gain unauthorized access to network devices. The exploitation process becomes significantly easier when attackers can obtain a single valid certificate or key from one device and use it to authenticate to other devices within the same product line. Security professionals should note that this vulnerability represents a design flaw rather than a runtime issue, meaning it exists in the firmware itself and cannot be mitigated through software patches alone without complete device replacement or firmware updates from the manufacturer. Organizations should implement immediate network segmentation and monitoring to detect potential exploitation attempts while planning for device replacement or firmware upgrades to address this fundamental security weakness.