CVE-2017-9307 in Disk
Summary
by MITRE
SSRF vulnerability in remotedownload.php in Allen Disk 1.6 allows remote authenticated users to conduct port scans and access intranet servers via a crafted file parameter.
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Analysis
by VulDB Data Team • 12/07/2022
The CVE-2017-9307 vulnerability represents a critical server-side request forgery flaw discovered in Allen Disk version 1.6 within the remotedownload.php component. This vulnerability exposes organizations to significant security risks by allowing authenticated attackers to manipulate the application's file parameter processing mechanism. The flaw stems from insufficient input validation and sanitization of user-supplied data, particularly when the application attempts to download files from remote locations. Attackers can exploit this weakness by crafting malicious file parameters that direct the application to establish connections to internal network services or perform port scanning activities that would otherwise be restricted by network firewalls.
The technical implementation of this vulnerability aligns with CWE-918, which specifically addresses server-side request forgery conditions where applications fail to properly validate or sanitize URLs or other network resource identifiers. The flaw operates by accepting user-provided URLs through the file parameter without adequate restrictions on the target destinations, enabling attackers to bypass normal network access controls. When authenticated users submit malicious URLs to the remotedownload.php script, the application processes these requests without proper validation, allowing the system to make connections to internal services that should remain isolated from external access. This behavior creates a pathway for reconnaissance activities and potential exploitation of internal network resources.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to perform port scanning operations against internal systems that are typically protected by firewalls and network segmentation. Security analysts should note that this vulnerability operates at the application layer and can be leveraged by attackers who have already obtained legitimate authentication credentials. The ability to scan internal ports and access intranet services significantly increases the attack surface and allows for more sophisticated reconnaissance activities. This vulnerability particularly affects organizations that rely on Allen Disk for file management and remote access capabilities, where internal network resources are not adequately protected from authenticated users within the application's access controls.
Organizations should implement multiple layers of defense to mitigate this vulnerability, including strict input validation for all user-supplied parameters, implementation of allowlists for acceptable URL schemes and domains, and proper network segmentation to isolate critical internal services. The remediation approach should focus on validating and sanitizing all external resource requests through the application, ensuring that only pre-approved domains or IP addresses can be accessed. Network-based mitigations should include implementing firewall rules that restrict outbound connections from the application server to internal networks, while application-level controls should enforce strict URL parsing and validation. Security teams should also consider implementing web application firewalls to monitor and block suspicious requests, and conduct regular security assessments to identify similar vulnerabilities in other application components. This vulnerability demonstrates the importance of implementing principle of least privilege controls and proper access validation within web applications, particularly those handling external resource requests. The ATT&CK framework categorizes this type of vulnerability under initial access and reconnaissance techniques, where attackers can establish persistent access and gather intelligence about internal network configurations through automated scanning activities.