CVE-2015-0730 in Wide Area Application Services
Summary
by MITRE
The SMB module in Cisco Wide Area Application Services (WAAS) 6.0(1) allows remote attackers to cause a denial of service (module reload) via an invalid field in a Negotiate Protocol request, aka Bug ID CSCuo75645.
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Analysis
by VulDB Data Team • 04/01/2019
The vulnerability identified as CVE-2015-0730 resides within the Server Message Block (SMB) module of Cisco Wide Area Application Services version 6.0(1), representing a critical denial of service weakness that enables remote attackers to disrupt service availability. This flaw manifests when the WAAS module encounters an invalid field within a Negotiate Protocol request, causing the affected module to reload automatically and consequently interrupting network operations. The issue specifically targets the SMB protocol implementation within the WAAS framework, which is designed to optimize WAN application performance by reducing bandwidth consumption and improving application response times. The vulnerability affects organizations relying on Cisco WAAS appliances for network optimization, potentially compromising business continuity and application availability across distributed networks.
The technical mechanism underlying this vulnerability involves improper input validation within the SMB protocol handler of the WAAS module. When a malicious actor sends a specially crafted Negotiate Protocol request containing an invalid field, the system fails to properly sanitize or reject the malformed input, leading to an unexpected module reload process. This behavior stems from inadequate error handling and validation routines in the SMB implementation, allowing crafted malformed packets to trigger an internal module restart rather than gracefully rejecting the invalid request. The vulnerability operates at the application layer protocol handling level, where the WAAS appliance processes SMB negotiation requests from remote clients without sufficient validation of field contents. According to CWE classification, this represents a weakness in input validation and error handling, specifically CWE-20, which deals with improper input validation, and CWE-707, which addresses improper use of APIs. The flaw essentially creates a condition where malformed protocol data can trigger an unintended system behavior, leading to service disruption.
The operational impact of CVE-2015-0730 extends beyond simple service interruption, potentially affecting business operations that depend on continuous WAN application performance optimization. Organizations utilizing WAAS appliances for critical applications such as ERP systems, VoIP services, or database replication may experience significant downtime when this vulnerability is exploited. The automatic module reload process can disrupt ongoing network communications, forcing applications to re-establish connections and potentially causing data loss or transaction failures. Network administrators may observe unexpected service interruptions and system logs indicating module restarts, complicating troubleshooting efforts and potentially leading to extended outage periods. The vulnerability's remote exploitability means that attackers do not require physical access or network credentials to trigger the denial of service condition, making it particularly dangerous in environments where network security controls may be insufficient. From an ATT&CK framework perspective, this vulnerability maps to T1499.004, which covers network disruption attacks, and T1595.001, involving reconnaissance of network endpoints, as attackers may first identify vulnerable WAAS installations before exploiting this specific weakness.
Mitigation strategies for CVE-2015-0730 primarily involve implementing immediate software updates and patches provided by Cisco to address the specific validation issues within the SMB module. Organizations should prioritize applying the relevant security patches released by Cisco as part of their vulnerability management processes, particularly focusing on updating WAAS appliances to versions that contain fixed SMB protocol handling routines. Network segmentation and access controls should be implemented to limit exposure of WAAS appliances to untrusted networks, reducing the attack surface for remote exploitation. Additional defensive measures include implementing network monitoring to detect unusual module reload patterns and configuring intrusion detection systems to identify malformed SMB negotiation requests. Organizations should also consider disabling SMB protocol handling on WAAS appliances when not required for specific applications, reducing the potential attack vectors. The vulnerability highlights the importance of maintaining current security patches and implementing proper input validation mechanisms in network infrastructure devices, particularly those handling protocol negotiations and application optimization tasks. Regular vulnerability assessments and security audits should be conducted to identify similar weaknesses in other network components and ensure comprehensive protection against similar denial of service threats.