CVE-2019-1854 in Expressway
Summary
by MITRE
A vulnerability in the management web interface of Cisco Expressway Series could allow an authenticated, remote attacker to perform a directory traversal attack against an affected device. The vulnerability is due to insufficient input validation on the web interface. An attacker could exploit this vulnerability by sending a crafted HTTP request to the web interface. A successful exploit could allow the attacker to bypass security restrictions and access the web interface of a Cisco Unified Communications Manager associated with the affected device. Valid credentials would still be required to access the Cisco Unified Communications Manager interface.
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Analysis
by VulDB Data Team • 09/12/2023
The vulnerability identified as CVE-2019-1854 affects Cisco Expressway Series devices and represents a critical directory traversal flaw in the management web interface. This vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing. The flaw exists within the web interface component of Cisco Expressway Series products, which are commonly deployed in unified communications environments to facilitate video conferencing and collaboration services. The vulnerability is particularly concerning because it allows authenticated remote attackers to exploit the weakness without requiring additional privileges beyond valid credentials.
The technical exploitation of this vulnerability occurs through crafted HTTP requests that manipulate the web interface's input handling mechanisms. When an attacker submits malicious input through the web interface, the insufficient validation allows the system to interpret and process directory traversal sequences such as ../ or ..\ that can navigate beyond the intended file access boundaries. This weakness enables attackers to bypass normal security restrictions and potentially access sensitive files or directories that should be protected. The vulnerability specifically targets the web interface's handling of user input, making it a classic example of improper input validation that falls under CWE-22, which describes directory traversal or path traversal vulnerabilities. Attackers can leverage this flaw to access the web interface of associated Cisco Unified Communications Manager systems, though they still require valid authentication credentials to access the underlying communication manager interface itself.
The operational impact of this vulnerability extends beyond simple unauthorized access to potentially compromise entire unified communications infrastructures. An attacker who successfully exploits this vulnerability could gain access to sensitive configuration data, user credentials, or system files that could be used for further attacks within the network. The vulnerability affects Cisco Expressway Series devices that are commonly used in enterprise environments where communication security is paramount, making the potential impact significant for organizations relying on these platforms. The exploitation requires an authenticated session, meaning that attackers must first obtain valid credentials, but once achieved, the vulnerability provides a pathway to escalate privileges and access associated systems. This type of attack pattern aligns with ATT&CK technique T1078 which covers valid accounts and T1566 which covers credential harvesting, making it a particularly dangerous vulnerability in the context of enterprise security.
Organizations affected by this vulnerability should implement immediate mitigations including applying the latest security patches from Cisco, which address the input validation issues in the web interface. Network segmentation and access controls should be enhanced to limit exposure of management interfaces to trusted networks only, reducing the attack surface. Regular monitoring of web interface access logs should be implemented to detect suspicious directory traversal attempts, which can serve as indicators of exploitation attempts. The vulnerability also highlights the importance of implementing robust input validation controls across all web applications and interfaces, particularly those handling user-supplied data. Security teams should conduct comprehensive vulnerability assessments to identify similar issues in other network devices and applications, as the underlying cause of this vulnerability - insufficient input validation - is a common weakness that can manifest in various forms across different systems. Additionally, implementing web application firewalls and intrusion detection systems can provide additional layers of protection against directory traversal attacks targeting web interfaces.