CVE-2019-1765 in IP Phone 8800
Summary
by MITRE
A vulnerability in the web-based management interface of Session Initiation Protocol (SIP) Software for Cisco IP Phone 8800 Series could allow an authenticated, remote attacker to write arbitrary files to the filesystem. The vulnerability is due to insufficient input validation and file-level permissions. An attacker could exploit this vulnerability by uploading invalid files to an affected device. A successful exploit could allow the attacker to write files in arbitrary locations on the filesystem. This vulnerability affects Cisco IP Phone 8800 Series products running a SIP Software release prior to 11.0(5) for Wireless IP Phone 8821 and 8821-EX; and 12.5(1)SR1 for the IP Conference Phone 8832 and the rest of the IP Phone 8800 Series.
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Analysis
by VulDB Data Team • 05/19/2020
The vulnerability identified as CVE-2019-1765 represents a critical security flaw in the web-based management interface of Cisco IP Phone 8800 Series devices running SIP Software. This issue stems from inadequate input validation mechanisms and improper file-level permissions that collectively create an exploitable condition within the device's file system operations. The vulnerability specifically targets the authentication and authorization controls that govern file upload operations, allowing malicious actors with valid credentials to manipulate the device's underlying file structure. The affected products include various models within the 8800 Series such as the Wireless IP Phone 8821 and 8821-EX, along with the IP Conference Phone 8832 and other devices in the series, all operating on software versions prior to the specified security patches.
The technical exploitation of this vulnerability occurs through a carefully crafted file upload attack that bypasses normal file validation procedures. Attackers with authenticated access can manipulate the web interface to upload malicious files that are then written to arbitrary locations within the device's file system. This flaw operates under the principle of insufficient input validation as classified by CWE-20, where the system fails to properly validate or sanitize user-supplied data before processing it. The vulnerability essentially allows for privilege escalation through file system manipulation, as the attacker can write files to locations that should normally be restricted. The weakness in file-level permissions means that the device does not adequately enforce access controls during file operations, enabling unauthorized file placement in critical system directories.
The operational impact of this vulnerability extends beyond simple file manipulation to encompass potential system compromise and persistent access. An attacker who successfully exploits this vulnerability can potentially install malicious software, modify system configuration files, or create backdoor access points within the device. This capability transforms a simple authentication bypass into a significant threat to network security, as compromised phones can serve as entry points for broader network infiltration. The vulnerability affects not just individual devices but can potentially enable attackers to establish persistent presence within enterprise networks where these phones are deployed, particularly in environments where phones are not regularly updated or monitored for security patches. The attack surface is further expanded by the fact that these devices are often deployed in mission-critical communication environments where unauthorized access could disrupt business operations.
Mitigation strategies for CVE-2019-1765 primarily focus on immediate software updates and enhanced network monitoring. Organizations should prioritize upgrading all affected Cisco IP Phone 8800 Series devices to the patched software versions specified in the security advisories, which include releases 11.0(5) for Wireless IP Phone 8821 and 8821-EX, and 12.5(1)SR1 for the IP Conference Phone 8832 and other 8800 Series devices. Network segmentation and access control measures should be implemented to limit the scope of potential exploitation, ensuring that only authorized personnel can access the web-based management interfaces. Additionally, organizations should conduct comprehensive vulnerability assessments to identify all devices running vulnerable software versions and establish monitoring protocols to detect unauthorized file system modifications. The ATT&CK framework categorizes this vulnerability under privilege escalation and persistence techniques, emphasizing the need for layered security controls that go beyond simple authentication to include file system integrity monitoring and network-based anomaly detection. Regular security audits and patch management processes should be implemented to prevent similar vulnerabilities from emerging in other network components.