CVE-2015-7845 in eSpace U1910
Summary
by MITRE
The exception handling mechanism in the CLI Module in Huawei eSpace U1910, U1911, U1930, U1960, U1980, and U1981 unified gateways with software before V100R001C20SPH605 allows remote attackers to cause a denial of service (CLI outage) via crafted SSH packets.
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Analysis
by VulDB Data Team • 04/13/2018
The vulnerability identified as CVE-2015-7845 resides within the command line interface module of Huawei's unified communication gateways, specifically affecting models including the eSpace U1910, U1911, U1930, U1960, U1980, and U1981 series. This flaw manifests in the improper handling of exception conditions within the SSH protocol implementation, creating a pathway for remote exploitation that can result in complete service disruption. The affected devices operate with software versions prior to V100R001C20SPH605, indicating that this represents a significant security gap in the product lifecycle that was not addressed until a later software patch release.
The technical mechanism underlying this vulnerability involves the inadequate exception handling within the CLI module's SSH subsystem. When remote attackers craft specific malformed SSH packets, the system fails to properly process these malformed inputs, leading to an unhandled exception that causes the CLI service to crash or become unresponsive. This represents a classic buffer overflow or input validation vulnerability where the system does not adequately sanitize incoming data before processing it within the command line interface context. The flaw specifically impacts the SSH protocol implementation which serves as the primary remote access mechanism for system administration and configuration management.
The operational impact of this vulnerability extends beyond simple service disruption to encompass complete denial of service conditions that can severely impact business continuity. When the CLI module becomes unresponsive, system administrators lose the ability to remotely manage and configure the unified gateway, effectively rendering the device unusable for its intended purpose. This creates a cascading effect where network communications may be disrupted, voice services may fail, and critical system maintenance operations cannot be performed. The vulnerability's remote nature means that attackers do not require physical access or local network presence to exploit the flaw, making it particularly dangerous in environments where remote access is frequently used for system administration.
This vulnerability aligns with CWE-248, an unspecified exception, which describes the situation where an exception is thrown but not properly caught, leading to program termination or unstable behavior. The flaw also relates to ATT&CK technique T1210, Exploitation of Remote Services, as it specifically targets a remote service (SSH) to achieve system compromise. Organizations utilizing these Huawei unified gateways face significant risk of operational disruption and potential security breaches, as the vulnerability can be exploited without authentication requirements and can be executed from any network location. The attack surface is particularly concerning given that SSH is commonly enabled for legitimate administrative access, making the exploitation of this vulnerability both feasible and potentially devastating to network infrastructure.
The recommended mitigation strategy involves immediate deployment of the patched software version V100R001C20SPH605 or later, which addresses the exception handling flaw in the CLI module. System administrators should also implement network segmentation to limit SSH access to trusted administrative networks, enforce strict access controls, and monitor for unusual SSH connection patterns that may indicate exploitation attempts. Additionally, organizations should conduct thorough vulnerability assessments to identify all affected devices within their network infrastructure and establish incident response procedures specifically tailored to handle potential CLI service outages. Regular security updates and patch management processes should be strengthened to prevent similar vulnerabilities from remaining unaddressed in future software releases.