CVE-2017-18110 in Atlassian Crowd
Summary
by MITRE
The administration backup restore resource in Atlassian Crowd before version 3.0.2 and from version 3.1.0 before version 3.1.1 allows remote attackers to read files from the filesystem via a XXE vulnerability.
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Analysis
by VulDB Data Team • 08/17/2023
The vulnerability identified as CVE-2017-18110 represents a critical XML External Entity processing flaw within Atlassian Crowd's administrative backup and restore functionality. This issue affects versions prior to 3.0.2 and specifically targets the 3.1.0 release series before 3.1.1, creating a persistent security weakness that enables remote attackers to exploit the system's XML parser. The vulnerability stems from inadequate input validation and sanitization within the backup restore resource, which processes XML data without proper restrictions on external entity references.
The technical exploitation of this XXE vulnerability allows attackers to perform unauthorized file system access by crafting malicious XML payloads that reference local files through external entity declarations. When the system processes these malformed XML inputs during backup restoration operations, it inadvertently resolves external entity references and exposes sensitive system files to remote attackers. This flaw operates at the application layer and can be leveraged without authentication, making it particularly dangerous as it bypasses normal access controls and privilege boundaries. The vulnerability aligns with CWE-611, which categorizes insecure direct object references and XML external entity processing issues, and maps to ATT&CK technique T1213.002 for data from information repositories, as attackers can extract sensitive data through this vector.
The operational impact of this vulnerability extends beyond simple file reading capabilities, as attackers can potentially access configuration files, database credentials, and other sensitive information stored within the application's file system. This exposure can lead to privilege escalation, lateral movement within the network, and complete system compromise. Organizations using affected Crowd versions face significant risk of data breaches, especially in environments where the application processes untrusted XML data from external sources. The vulnerability particularly affects enterprise environments where Crowd serves as a central identity management solution, potentially compromising user authentication and authorization mechanisms.
Mitigation strategies for CVE-2017-18110 require immediate patching of affected Crowd installations to versions 3.0.2 or 3.1.1 and later, which contain proper XML parsing restrictions and entity validation. Organizations should implement additional defensive measures including network segmentation, firewall rules restricting access to administrative interfaces, and monitoring for suspicious XML traffic patterns. Input validation should be strengthened to reject malformed XML content and disable external entity processing entirely within the application's XML parsers. Security teams should also conduct comprehensive vulnerability assessments to identify other potential XXE vulnerabilities in related systems and implement automated scanning tools to detect similar flaws. The remediation process must include thorough testing of backup and restore functionality to ensure that security patches do not disrupt legitimate administrative operations while maintaining the integrity of the system's backup mechanisms.