External risk intelligence

ASUS Router Authentication Bypass Vulnerability

CVE advisoryKnown Exploit

CVE-2021-32030

A vulnerability in ASUS routers allows authentication bypass, potentially granting attackers unauthorized access to the administrator interface. This poses a risk to organizational security by allowing unauthorized control over network settings and data.

5Halo Surface Signal

Authentication Bypass

Asus Lyra Mini Firmware

before 3.0.0.4.384.46630before 3.0.0.4.386.42643

External exposure likelihood

Halo Surface Signal score for CVE-2021-32030

The vulnerability affects the administrative interface of consumer routers. While remote management is an optional feature, it is a core functional capability designed to be exposed to the internet for remote access, making the administrative login portal directly reachable from the public internet if configured or enabled by the user.

Horizon Alert

Summary of the vulnerability and why it matters

ASUS routers, specifically the GT-AC2900 and Lyra Mini models, have a vulnerability that permits an attacker to bypass normal authentication procedures. This flaw allows unauthorized individuals to access the device's administrative interface. The potential impact includes unauthorized control over network settings and data, posing a significant risk to organizational security and operations.

Vulnerable administrative applications
Authentication bypass flaw
Unauthorized administrative access

Attack Path

How an attacker could exploit the issue

This vulnerability allows an unauthenticated user to bypass authentication when processing remote input. Attackers can gain unauthorized access to the administrator interface by exploiting this flaw. This could lead to a compromise of the device and its network.

Exposure: Remote administrator interface
Attacker access: Unauthenticated remote input
Trigger and result: Bypass authentication, gain admin access

Live Threat

Current exploitation, exposure, and threat context

This vulnerability allows an unauthenticated attacker to bypass authentication and gain unauthorized access to the administrator interface of affected ASUS devices. The attack can be performed remotely, requiring an attacker to possess a low skill level and exploit a weakness in how the device handles remote input. Successful exploitation could lead to a complete compromise of the device's administrative functions.

Low skill level attackers
No authentication required
High business risk; urgent action advised

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

An authentication bypass vulnerability exists in the administrator application of certain ASUS routers. This vulnerability could allow an unauthenticated user to gain unauthorized access to the administrator interface. Organizations with affected devices should take immediate steps to identify and mitigate their risk.

Find all affected ASUS router assets.
Disable remote access from the WAN.
Apply vendor firmware updates.
Verify updates were successful.
Monitor for related security incidents.

Frequently asked questions

What is the authentication bypass vulnerability affecting ASUS routers?

The ASUS GT-AC2900 and Lyra Mini routers have a vulnerability in their administrator application that allows unauthenticated users to bypass authentication when processing remote input. This grants unauthorized access to the administrator interface, potentially leading to a compromise of network settings and data. The weakness lies in how the device handles remote input, where an attacker-supplied value can match the device's default value in certain situations.

What is the weakness class and trigger path for the ASUS router vulnerability?

The weakness class is CWE-287, which pertains to improper authentication. The trigger path involves processing remote input from an unauthenticated user. Specifically, an attacker can supply a value of '\0' which, in some scenarios, matches the device's default '\0' value, thus bypassing the authentication mechanism and granting unauthorized access to the administrator interface.

How can an attacker exploit the ASUS router authentication bypass vulnerability?

An attacker can exploit this vulnerability by sending specially crafted remote input to the administrator application. By supplying a specific value, such as '\0', the attacker can bypass the authentication checks. This allows them to gain unauthorized access to the administrator interface without needing any credentials, enabling them to control the device's network settings.

What is the relevance of the ASUS router vulnerability, and why is it a concern?

This vulnerability is highly relevant because it allows unauthenticated, remote attackers with a low skill level to gain full administrative control over affected ASUS routers. The Halo Surface Signal indicates it's 'Very likely' to be exploited due to the administrative interface being directly reachable from the internet if remote management is enabled. Successful exploitation could lead to significant security breaches and operational disruption.

What practical steps should be taken to address the ASUS router vulnerability?

To address this vulnerability, organizations should first identify all affected ASUS GT-AC2900 and Lyra Mini router assets. The most immediate mitigation is to disable remote access features from the WAN. Additionally, applying the latest vendor firmware updates (version 3.0.0.4.386.42643 for GT-AC2900 and 3.0.0.4_384_46630 for Lyra Mini) is crucial. After applying updates, verify their successful installation and monitor for any related security incidents.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.