CVE-2020-9544 in DSL-2640B E1
Summary
by MITRE
An issue was discovered on D-Link DSL-2640B E1 EU_1.01 devices. The administrative interface doesn't perform authentication checks for a firmware-update POST request. Any attacker that can access the administrative interface can install firmware of their choice.
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Analysis
by VulDB Data Team • 04/09/2024
The vulnerability identified as CVE-2020-9544 affects D-Link DSL-2640B E1 EU_1.01 wireless routers and represents a critical authentication bypass flaw in the device's administrative interface. This weakness stems from inadequate input validation and access control mechanisms within the firmware update functionality, creating a significant security risk for network infrastructure. The vulnerability exists in the web-based management interface that allows remote administration of the device, specifically targeting the firmware update POST request handler which fails to verify user credentials or authorization status before processing the update command.
This authentication flaw falls under the CWE-287 category of improper authentication, where the system fails to properly verify the identity of users attempting to perform privileged operations. The vulnerability creates a direct path for unauthorized firmware installation, as the device does not validate whether the request originates from an authenticated administrator or an unauthenticated attacker. The issue is particularly concerning because it allows remote code execution through firmware manipulation, as attackers can upload and install malicious firmware versions that could compromise the device's integrity and functionality. The affected device model represents a consumer-grade router that typically serves as a primary network gateway, making it a valuable target for attackers seeking persistent access to network environments.
The operational impact of this vulnerability extends beyond simple unauthorized firmware installation, as it creates potential for complete device compromise and network infiltration. Attackers can leverage this flaw to install backdoor firmware, modify network configurations, redirect traffic, or establish persistent access points within the network infrastructure. The vulnerability's remote exploitability means that attackers do not require physical access to the device, making it particularly dangerous for enterprise environments where such devices may be exposed to external networks. From an attack chain perspective, this vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter and T1068 for exploit for privilege escalation, as it enables attackers to gain elevated privileges through unauthorized firmware manipulation.
Mitigation strategies for CVE-2020-9544 should prioritize immediate network segmentation and access control implementation to restrict access to administrative interfaces. Organizations should ensure that administrative interfaces are not directly exposed to untrusted networks and implement strong authentication mechanisms including multi-factor authentication where possible. Device firmware should be updated to versions that address the authentication bypass issue, with vendors releasing patches to correct the improper validation of POST request parameters. Network monitoring should be enhanced to detect unusual firmware update activities, and access logging should be implemented to track administrative interface usage. The vulnerability also underscores the importance of network access control policies and the need for regular security assessments of network infrastructure devices to identify similar authentication bypass flaws that could compromise network security.