关键信息 Title Missing Brute-Force Protection on UART Diagnostic Authentication Mechanism Affected Product Product: Beetel 777VR1 Broadband Router Firmware Version: V01.00.09 / V01.00.09_55 Distribution: ISP-provisioned firmware Vulnerability Type Improper Authentication Attempt Restriction CWE CWE-307 — Improper Restriction of Excessive Authentication Attempts Severity Critical Attack Vector Physical (UART) Description The UART-based diagnostic authentication mechanism on the Beetel 777VR1 router does not implement any form of brute-force protection. The interface allows unlimited authentication attempts without rate limiting, delay, CAPTCHA, or account lockout. An attacker with physical access can repeatedly attempt credentials without restriction, enabling credential guessing or brute-force attacks against administrative accounts. This weakness exists regardless of password strength and significantly reduces the effort required to obtain unauthorized access. Impact Increased likelihood of successful credential compromise leading to unauthorized diagnostic shell access. The BEETEL 777VR1 router is widely deployed in India in residential and small-enterprise environments by ISPs. Due to its prevalence and default configurations, successful exploitation impacts a large number of installations. Preconditions Physical access to the UART interface Device running affected firmware Evidence/Proof Included screenshot showing repeated authentication attempts. Exploitability High. Unlimited attempts enable rapid brute-force or credential-stuffing attacks. Mitigation Implement authentication rate limiting Introduce exponential back-off or fixed delays Lock accounts after repeated failed attempts Log and alert on repeated authentication failures Credit Discovered and reported by: RAGHAV AGRAWAL