CVE-2018-20675 in DIR-850L C1
Summary
by MITRE
D-Link DIR-822 C1 before v3.11B01Beta, DIR-822-US C1 before v3.11B01Beta, DIR-850L A* before v1.21B08Beta, DIR-850L B* before v2.22B03Beta, and DIR-880L A* before v1.20B02Beta devices allow authentication bypass.
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Analysis
by VulDB Data Team • 04/26/2020
The vulnerability identified as CVE-2018-20675 affects multiple D-Link router models including DIR-822 and DIR-850L series devices. This authentication bypass flaw represents a critical security weakness that allows unauthorized users to gain administrative access to affected network equipment without proper credentials. The vulnerability specifically impacts firmware versions prior to the specified beta releases, indicating that D-Link had acknowledged and addressed this issue in their subsequent software updates. The affected devices operate within the consumer and small office networking segment, making them attractive targets for attackers seeking to compromise home and small business network infrastructures. This type of vulnerability directly undermines the fundamental security posture of network devices by eliminating the primary authentication mechanism that should protect administrative functions.
The technical implementation of this authentication bypass stems from improper validation of user credentials within the web-based administration interface of these routers. The flaw likely exists in how the device handles session management or credential verification processes, potentially allowing attackers to bypass the login screen entirely or exploit weak authentication mechanisms. According to CWE classification, this vulnerability aligns with CWE-287 which addresses improper authentication issues, specifically focusing on authentication bypass scenarios where legitimate authentication checks are circumvented. The vulnerability's impact extends beyond simple unauthorized access as it provides attackers with complete administrative control over the affected routers, enabling them to modify network configurations, intercept traffic, or establish persistent access points within the network.
From an operational perspective, this vulnerability creates significant risk for organizations and individuals using affected D-Link devices, as it enables attackers to assume full administrative control over network infrastructure. The compromised devices can serve as entry points for broader network attacks, allowing threat actors to pivot to other systems within the local network or establish backdoors for continued access. The attack surface is particularly concerning given that these devices are typically deployed in environments where network security is not adequately considered, such as home offices or small businesses. The vulnerability's persistence across multiple device models and firmware versions indicates a systemic issue within D-Link's development and testing processes, potentially affecting thousands of devices in the wild. This type of vulnerability also aligns with ATT&CK technique T1078 which covers valid accounts and legitimate credentials for lateral movement and persistence within networks.
The recommended mitigation strategy involves immediate firmware updates from D-Link to address the authentication bypass vulnerability. Network administrators should prioritize updating all affected devices to the latest stable firmware versions that contain the necessary security patches. Additionally, organizations should implement network segmentation to limit the potential impact of compromised devices and monitor network traffic for suspicious activities that might indicate exploitation attempts. The vulnerability highlights the importance of maintaining current firmware versions and conducting regular security assessments of network infrastructure components. Network defenders should also consider implementing additional monitoring controls specifically designed to detect unauthorized access attempts to network administration interfaces, as the authentication bypass may not always be immediately apparent through standard network monitoring tools.