CVE-2016-7964 in DokuWiki
Summary
by MITRE
The sendRequest method in HTTPClient Class in file /inc/HTTPClient.php in DokuWiki 2016-06-26a and older, when media file fetching is enabled, has no way to restrict access to private networks. This allows users to scan ports of internal networks via SSRF, such as 10.0.0.1/8, 172.16.0.0/12, and 192.168.0.0/16.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/29/2022
The vulnerability identified as CVE-2016-7964 resides within the HTTPClient class of DokuWiki version 2016-06-26a and earlier installations, specifically in the sendRequest method located at /inc/HTTPClient.php. This flaw represents a critical server-side request forgery vulnerability that enables remote attackers to bypass network access controls and perform unauthorized network scanning of internal network segments. The vulnerability occurs when media file fetching functionality is enabled, creating a pathway for malicious actors to leverage the wiki's HTTP client to make requests to private network addresses that should normally be restricted from external access.
The technical implementation of this vulnerability stems from inadequate network boundary checks within the HTTPClient's sendRequest method. When DokuWiki processes requests for media files, it utilizes the HTTPClient to fetch resources from remote servers. However, the implementation fails to validate or restrict destination addresses against private network ranges, including Class A private networks 10.0.0.0/8, Class B private networks 172.16.0.0/12, and Class C private networks 192.168.0.0/16. This absence of network validation allows attackers to craft requests that target internal network addresses, effectively enabling them to perform port scanning and network reconnaissance against the organization's internal infrastructure. The vulnerability is classified as a CWE-918 Server-Side Request Forgery, which is a specific type of vulnerability that allows attackers to make requests through a vulnerable application to internal systems that would normally be protected by network firewalls or other access controls.
The operational impact of this vulnerability is significant and multifaceted, creating potential for both reconnaissance and exploitation activities. Attackers can leverage this vulnerability to map internal network topology, identify open ports and services running on internal hosts, and potentially discover sensitive systems that should remain hidden from external access. The ability to scan private network ranges effectively bypasses standard network security controls, as the attack originates from within the trusted network boundary of the web application. This vulnerability can be exploited to gain intelligence about internal systems, potentially leading to more sophisticated attacks such as service enumeration, vulnerability scanning, or even direct exploitation of internal services that may not be properly secured. The impact extends beyond simple information gathering, as it can facilitate lateral movement within networks and enable attackers to identify potential attack vectors that would otherwise remain hidden.
Mitigation strategies for CVE-2016-7964 should focus on both immediate patching and network-level controls. The most effective solution is to upgrade to DokuWiki version 2016-07-04 or later, which includes proper network boundary validation and access restriction mechanisms. Organizations should also implement network-level controls such as firewall rules that prevent outbound connections to private network ranges from the web server hosting DokuWiki, and consider implementing network segmentation to isolate the web application from internal network resources. Additional mitigations include configuring the HTTPClient to use a proxy server with appropriate access controls, implementing strict URL validation for media file requests, and monitoring network traffic for suspicious outbound connections to private network addresses. From an ATT&CK perspective, this vulnerability maps to T1133 External Remote Services and T1046 Network Service Scanning, indicating that defenders should implement appropriate network monitoring and access control measures to prevent such reconnaissance activities from occurring within their environments.