CVE-2017-11149 in Download Station
Summary
by MITRE
Server-side request forgery (SSRF) vulnerability in Downloader in Synology Download Station 3.8.x before 3.8.5-3475 and 3.x before 3.5-2984 allows remote authenticated users to download arbitrary local files via crafted URI.
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Analysis
by VulDB Data Team • 12/15/2022
The CVE-2017-11149 vulnerability represents a critical server-side request forgery flaw within Synology Download Station's Downloader component, specifically affecting versions prior to 3.8.5-3475 and 3.x versions before 3.5-2984. This vulnerability resides in the server-side processing logic that handles URI requests, creating a dangerous pathway for authenticated attackers to exploit. The flaw enables remote attackers with valid credentials to manipulate the download functionality and access arbitrary local files on the server system, fundamentally compromising the integrity and confidentiality of the affected environment. The vulnerability stems from insufficient input validation and sanitization of URI parameters, allowing maliciously crafted requests to traverse the intended download boundaries.
The technical implementation of this SSRF vulnerability occurs through the Downloader module's improper handling of user-supplied URI data. When authenticated users submit download requests with crafted URI parameters, the system fails to properly validate or sanitize the input before processing. This allows attackers to construct malicious URIs that can bypass normal access controls and potentially reach internal resources or local file systems. The vulnerability specifically targets the URI parsing mechanism within the download station's server-side components, where the system processes requests without adequate restrictions on the protocols or file paths that can be accessed. This flaw aligns with CWE-918, which categorizes server-side request forgery vulnerabilities as those that allow attackers to manipulate server-side requests to access resources that should otherwise be restricted.
The operational impact of CVE-2017-11149 extends beyond simple unauthorized file access, as it provides attackers with potential access to sensitive system information, configuration files, and potentially system credentials stored locally on the server. An attacker could leverage this vulnerability to extract database files, application configuration data, or system logs that might contain sensitive information. The vulnerability also opens possibilities for further exploitation, including potential privilege escalation or lateral movement within the network environment. Attackers could use the compromised download station to access internal network resources that are normally protected from external access, effectively turning the vulnerable system into a potential pivot point for broader network attacks. This vulnerability directly relates to ATT&CK technique T1071.004, which covers application layer protocol tunneling, as the malicious requests can bypass normal network controls to access restricted resources.
Mitigation strategies for this vulnerability require immediate patching of affected Synology Download Station versions to the latest releases that contain the necessary security fixes. Organizations should also implement network-level controls such as firewall rules to restrict access to internal resources from the download station service, particularly when it operates in environments with mixed trust levels. Additional security measures include implementing proper input validation for all URI parameters, using allowlists for permitted protocols and destinations, and regularly monitoring download station logs for suspicious activity patterns. The vulnerability highlights the importance of secure coding practices in server-side applications, particularly around URI handling and input validation, as outlined in OWASP Top Ten categories related to injection flaws and insecure deserialization. Network segmentation and principle of least privilege should be enforced to limit the potential impact of such vulnerabilities, ensuring that even if an attacker compromises one component, they cannot easily access other sensitive systems within the organization.