CVE-2016-6901 in AR100
Summary
by MITRE
Format string vulnerability in Huawei AR100, AR120, AR150, AR200, AR500, AR550, AR1200, AR2200, AR2500, AR3200, and AR3600 routers with software before V200R007C00SPC900 and NetEngine 16EX routers with software before V200R007C00SPC900 allows remote authenticated users to cause a denial of service via format string specifiers in vectors involving partial commands.
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Analysis
by VulDB Data Team • 09/21/2022
This vulnerability represents a critical format string flaw in Huawei's enterprise routing infrastructure affecting multiple router models including AR100, AR120, AR150, AR200, AR500, AR550, AR1200, AR2200, AR2500, AR3200, AR3600, and NetEngine 16EX devices. The vulnerability resides in the command processing mechanism where the system fails to properly validate user input before using it in format string operations. This flaw specifically impacts devices running software versions prior to V200R007C00SPC900, creating a persistent security risk across Huawei's router portfolio. The vulnerability is classified under CWE-134 as improper use of format string, which is a well-documented weakness in software security that occurs when format string arguments are constructed from untrusted input without proper validation or sanitization. The attack vector involves authenticated remote users who can manipulate partial commands to inject format string specifiers, exploiting the lack of input validation in the command processing pipeline.
The operational impact of this vulnerability extends beyond simple denial of service, creating significant risks for network infrastructure security. When exploited, the format string vulnerability allows attackers to cause system instability, leading to complete service disruption of the affected routers. The remote authenticated nature of the attack means that an attacker with valid credentials can leverage this flaw to compromise network availability, potentially disrupting critical business operations and communications. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1499.004 for Network Denial of Service, where attackers manipulate system resources to deny service to legitimate users. The flaw affects the core command processing functionality of the routers, which means that even legitimate administrative operations could be disrupted, potentially preventing network administrators from maintaining their systems during an attack. The vulnerability's persistence across multiple router families indicates a fundamental design flaw in the software implementation rather than an isolated incident.
The technical exploitation of this vulnerability requires an authenticated session to the affected router, which limits the attack surface but does not eliminate the risk. Attackers can craft malicious commands containing format string specifiers that, when processed by the vulnerable software, cause the system to behave unpredictably. This can result in memory corruption, stack manipulation, or other low-level system failures that lead to denial of service conditions. The vulnerability is particularly concerning because it affects enterprise-grade networking equipment that typically operates in critical infrastructure environments where availability is paramount. Network administrators may not immediately detect the exploitation due to the subtle nature of format string attacks, which can manifest as intermittent service disruptions rather than clear system crashes. The affected software versions represent a significant portion of Huawei's router installations, making this vulnerability a widespread concern for organizations relying on these devices for their network infrastructure. Organizations should implement immediate mitigation strategies including software updates, network segmentation to limit access, and monitoring for suspicious command usage patterns to prevent exploitation.