CVE-2018-15396 in Unity Connection
Summary
by MITRE
A vulnerability in the Bulk Administration Tool (BAT) for Cisco Unity Connection could allow an authenticated, remote attacker to cause high disk utilization, resulting in a denial of service (DoS) condition. The vulnerability exists because the affected software does not restrict the maximum size of certain files that can be written to disk. An attacker who has valid administrator credentials for an affected system could exploit this vulnerability by sending a crafted, remote connection request to an affected system. A successful exploit could allow the attacker to write a file that consumes most of the available disk space on the system, causing application functions to operate abnormally and leading to a DoS condition.
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Analysis
by VulDB Data Team • 05/22/2023
The vulnerability identified as CVE-2018-15396 resides within Cisco Unity Connection's Bulk Administration Tool, representing a critical security flaw that enables authenticated remote attackers to execute denial of service attacks through excessive disk space consumption. This weakness specifically targets the file handling mechanisms within the BAT component, where proper input validation and size restrictions are absent, creating an avenue for malicious exploitation that directly impacts system availability and operational integrity.
The technical flaw manifests as a lack of proper file size limitations within the Bulk Administration Tool's disk writing operations. When an authenticated administrator with valid credentials sends a crafted remote connection request, the system fails to enforce maximum file size constraints, allowing an attacker to upload or generate files of arbitrary size that rapidly consume available disk space. This design oversight creates a condition where disk utilization can escalate to critical levels, ultimately rendering the system incapable of performing normal operations due to insufficient storage capacity for legitimate application functions.
From an operational perspective, this vulnerability presents a significant risk to organizations relying on Cisco Unity Connection for voice messaging and collaboration services. The impact extends beyond simple service disruption to potentially compromising business continuity, as the DoS condition affects core communication infrastructure that may support critical operations. The vulnerability's remote exploitation capability means that attackers do not require physical access or local network presence, making it particularly dangerous in environments where network segmentation may not adequately protect administrative interfaces.
The attack vector for this vulnerability aligns with common exploitation patterns documented in the attack mitigation framework, where authenticated access combined with insufficient input validation creates a pathway for resource exhaustion attacks. This flaw demonstrates characteristics consistent with CWE-770, which addresses allocation of resources without proper limits, and relates to broader concepts within the ATT&CK framework under privilege escalation and resource consumption tactics. Organizations with administrative access to affected systems are particularly vulnerable, as the attack requires only valid credentials rather than complex exploitation techniques.
Mitigation strategies should focus on implementing proper file size restrictions and disk space monitoring within the Bulk Administration Tool configuration. Cisco has released patches and updates to address this vulnerability, which should be applied immediately to affected systems. Network segmentation and access control measures can help limit the scope of potential exploitation, while regular disk space monitoring and alerting mechanisms can provide early detection of abnormal resource consumption patterns. Additionally, implementing rate limiting and file size validation controls within the application layer provides defense-in-depth protection against similar vulnerabilities in other components.