CVE-2023-36091 in DIR-895
Summary
by MITRE • 07/31/2023
** UNSUPPORTED WHEN ASSIGNED ** Authentication Bypass vulnerability in D-Link DIR-895 FW102b07 allows remote attackers to gain escalated privileges via via function phpcgi_main in cgibin. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.
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Analysis
by VulDB Data Team • 07/12/2024
This authentication bypass vulnerability exists in the D-Link DIR-895 router firmware version FW102b07 and represents a critical security flaw that allows remote attackers to escalate privileges without proper authentication. The vulnerability specifically targets the phpcgi_main function within the cgi-bin directory, which serves as a gateway for executing PHP scripts on the device. The flaw enables attackers to bypass the standard authentication mechanisms that should protect administrative functions, potentially granting them full control over the router's configuration and network settings.
The technical implementation of this vulnerability stems from improper input validation and access control mechanisms within the web interface's PHP processing component. When the phpcgi_main function processes requests, it fails to adequately verify user credentials or implement proper authorization checks before executing administrative functions. This design flaw allows malicious actors to craft specific HTTP requests that circumvent the normal authentication flow and directly invoke privileged operations. The vulnerability's remote exploitability means that attackers do not require physical access to the device or local network presence to exploit it, making it particularly dangerous in exposed network environments.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it provides attackers with complete administrative control over the affected router. This includes the ability to modify network configurations, change administrator credentials, disable security features, and potentially establish persistent backdoors. Network defenders face significant challenges when dealing with such vulnerabilities, as they may remain undetected for extended periods while attackers maintain persistent access to the network infrastructure. The compromised router can serve as a pivot point for further attacks within the internal network, potentially enabling lateral movement and data exfiltration activities.
Given that this vulnerability affects a product that is no longer supported by the manufacturer, organizations must implement immediate mitigations to protect their networks. The most effective approach involves isolating affected devices from critical network segments and implementing network segmentation controls to limit potential attack vectors. Network administrators should also consider deploying intrusion detection systems that can identify suspicious traffic patterns associated with exploitation attempts. Additionally, organizations should conduct comprehensive network scans to identify all instances of the affected firmware versions and develop contingency plans for device replacement or firmware updates where possible. This vulnerability aligns with CWE-287 which addresses improper authentication issues, and represents a significant concern under the ATT&CK framework's privilege escalation techniques, specifically targeting the use of unauthenticated administrative interfaces for unauthorized system access.