CVE-2017-16250 in Mitel ST
Summary
by MITRE
A vulnerability in Mitel ST 14.2, release GA28 and earlier, could allow an attacker to use the API function to enumerate through user-ids which could be used to identify valid user ids and associated user names.
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Analysis
by VulDB Data Team • 01/12/2020
The vulnerability identified as CVE-2017-16250 resides within Mitel ST 14.2 release GA28 and earlier versions of the communication platform. This issue represents a significant security flaw that undermines the system's authentication and authorization mechanisms by exposing user enumeration capabilities through the application programming interface. The vulnerability allows unauthorized actors to systematically discover valid user identifiers and associated usernames, creating a pathway for further malicious activities.
The technical implementation flaw stems from insufficient input validation and access control measures within the API functions that handle user identification requests. When legitimate authentication attempts are made through the vulnerable interface, the system fails to properly sanitize or limit the responses provided to unauthorized users. This weakness enables attackers to perform iterative queries against the API endpoints, gradually mapping out the user directory structure and identifying valid accounts within the system. The flaw operates at the application layer and specifically targets the authentication and user management components of the Mitel ST platform.
The operational impact of this vulnerability extends beyond simple information disclosure, creating a foundation for more sophisticated attacks within the compromised environment. An attacker who successfully exploits this vulnerability can construct comprehensive user directories that may include administrative accounts and privileged users. This enumeration capability enables social engineering campaigns, targeted phishing attacks, and brute force authentication attempts against identified valid accounts. The vulnerability also potentially facilitates privilege escalation scenarios where attackers can identify high-value targets within the user base for further exploitation.
Security professionals should recognize this vulnerability as a variant of CWE-200 Information Exposure, where the system inadvertently reveals sensitive information about its internal structure through improper error handling or response design. The attack pattern aligns with techniques documented in the ATT&CK framework under T1087 Account Discovery, where adversaries systematically identify user accounts and permissions within target systems. Organizations utilizing affected Mitel ST versions face elevated risk of credential theft, unauthorized access, and potential data breaches when this vulnerability remains unaddressed.
Mitigation strategies should prioritize immediate implementation of API rate limiting and access control restrictions to prevent automated enumeration attempts. Organizations must ensure that API responses do not provide distinguishing information between valid and invalid user identifiers, implementing consistent error handling across all authentication endpoints. The recommended remediation includes updating to Mitel ST 14.2 release GA29 or later versions that contain patched implementations of the affected API functions. Additionally, network-level controls such as firewall rules and intrusion detection systems should be configured to monitor and restrict access to the vulnerable API endpoints, while comprehensive logging should be enabled to detect suspicious enumeration patterns and unauthorized access attempts.