Source: cret@cert.org
Belkin F9K1102 2 devices with firmware 2.10.17 rely on client-side JavaScript code for authorization, which allows remote attackers to obtain administrative privileges via certain changes to LockStatus and Login_Success values.
Belkin F9K1102 routers running firmware 2.10.17 are vulnerable to a critical flaw where client-side JavaScript authorization is bypassed, allowing remote attackers to gain administrative control. This vulnerability enables attackers to fully compromise the router, potentially leading to network breaches and data exfiltration, impacting confidentiality, integrity, and availability.
Step 1: Target Identification: Identify a vulnerable Belkin F9K1102 router running firmware 2.10.17.
Step 2: Request Interception: Intercept HTTP requests sent to the router, typically using a proxy like Burp Suite or by crafting the requests manually.
Step 3: Parameter Manipulation: Modify the HTTP requests to include or alter the values of LockStatus and Login_Success. The attacker sets these values to indicate a successful login and unlocked status, bypassing the authentication.
Step 4: Request Submission: Send the modified HTTP request to the router.
Step 5: Administrative Access: The router, trusting the manipulated client-side data, grants administrative access to the attacker.
The vulnerability stems from flawed client-side authorization logic implemented in JavaScript. The router relies on JavaScript code to determine user privileges based on the values of LockStatus and Login_Success variables. Attackers can manipulate these variables through crafted HTTP requests, bypassing the intended authentication process. The root cause is the lack of server-side validation of these critical values. The JavaScript code on the client-side is trusted to enforce access control, which is easily circumvented. This is a classic example of insecure design where the security boundary is placed on the client, making it trivial to bypass.
While no specific APTs are directly linked to this CVE, the ease of exploitation makes it attractive to various threat actors. This type of vulnerability is often used by attackers for initial access and lateral movement. This CVE is not listed in the CISA KEV catalog.
Analyze router logs for suspicious HTTP requests, specifically those targeting administrative interfaces with unusual LockStatus or Login_Success values.
Monitor network traffic for unusual patterns, such as repeated attempts to access administrative pages without proper authentication.
Implement a Network Intrusion Detection System (NIDS) with rules to detect malicious HTTP requests that manipulate LockStatus and Login_Success parameters.
Examine the router's configuration files for unauthorized changes.
Upgrade the router's firmware to a patched version (if available).
Implement server-side validation of all user input, including LockStatus and Login_Success values.
Disable remote administration if not required.
Change the default administrative password to a strong, unique password.
Segment the network to limit the impact of a compromised router.
Regularly audit router configurations and logs for suspicious activity.