CVE-2017-9447 in Remote Application Server
Summary
by MITRE
In the web interface of Parallels Remote Application Server (RAS) 15.5 Build 16140, a vulnerability exists due to improper validation of the file path when requesting a resource under the "RASHTML5Gateway" directory. A remote, unauthenticated attacker could exploit this weakness to read arbitrary files from the vulnerable system using path traversal sequences.
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Analysis
by VulDB Data Team • 01/09/2020
The vulnerability identified as CVE-2017-9447 affects Parallels Remote Application Server version 15.5 Build 16140 and resides within its web interface component. This security flaw specifically impacts the RASHTML5Gateway directory functionality where the application fails to properly validate file paths during resource requests. The vulnerability represents a critical path traversal issue that allows malicious actors to access sensitive system files without authentication. The flaw exists in the web application's input sanitization mechanisms, where user-supplied path parameters are not adequately filtered or validated before being processed by the server's file system operations.
The technical implementation of this vulnerability stems from insufficient input validation within the web server's request handling logic. When a user submits a request to the RASHTML5Gateway directory, the application processes the file path parameter without proper sanitization measures. This allows attackers to inject directory traversal sequences such as ../ or ..\ into the requested file path, effectively bypassing normal file system access controls. The vulnerability aligns with CWE-22 - Improper Limitation of a Pathname to a Restricted Directory, which specifically addresses path traversal attacks that occur when applications fail to properly validate or sanitize file path inputs. The attack vector is particularly dangerous because it requires no authentication credentials, making it accessible to any remote attacker who can reach the vulnerable web interface.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with unrestricted access to the underlying file system of the affected server. An attacker could potentially read system configuration files, database credentials, application source code, and other sensitive data that may contain authentication tokens or other critical information. The vulnerability affects the confidentiality and integrity of the system, as unauthorized access to these files could lead to further exploitation opportunities including privilege escalation or complete system compromise. Organizations using Parallels RAS may face significant security implications, particularly in environments where the server hosts sensitive corporate data or serves as a gateway to internal networks. This vulnerability also violates fundamental security principles outlined in the NIST Cybersecurity Framework, specifically addressing the protection of information systems and the prevention of unauthorized access to sensitive data.
Mitigation strategies for CVE-2017-9447 should focus on immediate patching of the affected Parallels RAS version, as the vendor has likely released a security update addressing this specific path traversal vulnerability. Organizations should implement network segmentation to limit access to the vulnerable web interface, ensuring that only authorized personnel can reach the affected system. Input validation controls should be strengthened at the application level, including implementing proper path normalization and restricting file access to predefined directories. The principle of least privilege should be enforced by configuring the web server to operate with minimal required permissions and by implementing strict file access controls. Additionally, organizations should deploy web application firewalls and intrusion detection systems to monitor for suspicious path traversal attempts, which aligns with ATT&CK technique T1213 - Data from Information Repositories, as these systems can detect and prevent exploitation attempts. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other web applications within the organization's attack surface, ensuring comprehensive protection against similar path traversal attacks.