CVE-2017-18108 in Atlassian Crowd
Summary
by MITRE
The administration SMTP configuration resource in Atlassian Crowd before version 2.10.2 allows remote attackers with administration rights to execute arbitrary code via a JNDI injection.
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Analysis
by VulDB Data Team • 08/17/2023
The vulnerability identified as CVE-2017-18108 represents a critical remote code execution flaw within Atlassian Crowd's administrative SMTP configuration functionality. This issue affects versions prior to 2.10.2 and stems from insufficient input validation in the email server configuration interface. Attackers with administrative privileges can exploit this weakness by crafting malicious JNDI (Java Naming and Directory Interface) references within the SMTP settings, which then get processed by the application's backend components. The flaw operates through a classic server-side request forgery pattern where the application fails to properly sanitize user-supplied data before using it in JNDI lookups. This vulnerability directly maps to CWE-94, which describes the weakness of executing arbitrary code due to insufficient input validation and improper sanitization of external data sources. The attack vector is particularly dangerous because it requires only administrative access, which is often more limited than general user access but still represents a significant privilege escalation opportunity for attackers who have already gained foothold in the system.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to completely compromise the Crowd server and potentially gain access to all user accounts, authentication data, and integrated applications that rely on Crowd for identity management. The JNDI injection mechanism allows attackers to redirect the application's lookup requests to malicious LDAP or RMI servers they control, enabling them to execute arbitrary commands on the target system with the privileges of the Crowd application user. This creates a pathway for lateral movement throughout the network, as Crowd often serves as a central authentication hub for multiple applications and services. The vulnerability's exploitation aligns with ATT&CK technique T1059.007, which involves executing commands through the Windows Command Shell or similar system interfaces, and T1078.004, which covers legitimate credentials used for logon and authentication. Organizations using Crowd for identity management face significant risk exposure, as this vulnerability can lead to complete system compromise and data breaches.
Mitigation strategies for CVE-2017-18108 require immediate patching of affected Crowd installations to version 2.10.2 or later, which includes proper input validation and sanitization of SMTP configuration parameters. Administrators should also implement network-level restrictions to prevent outbound connections to untrusted external servers, particularly those that might be used for JNDI lookups. The principle of least privilege should be enforced by limiting administrative access to only those users who absolutely require it, and by implementing multi-factor authentication for all administrative accounts. Additional defensive measures include monitoring network traffic for suspicious JNDI lookup patterns, implementing application firewalls to block unauthorized outbound connections, and conducting regular security assessments of the Crowd configuration. Organizations should also review their overall identity and access management practices, as this vulnerability highlights the critical importance of securing administrative interfaces and validating all user-supplied data. The remediation process should include thorough testing of the patched environment to ensure that legitimate SMTP configurations continue to function properly while the vulnerability is eliminated.