CVE-2016-9417 in MyBB
Summary
by MITRE
The fetch_remote_file function in MyBB (aka MyBulletinBoard) before 1.8.8 and MyBB Merge System before 1.8.8 allows remote attackers to conduct server-side request forgery (SSRF) attacks via unspecified vectors.
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Analysis
by VulDB Data Team • 08/08/2020
The vulnerability identified as CVE-2016-9417 affects MyBulletinBoard (MyBB) and its Merge System versions prior to 1.8.8, presenting a critical server-side request forgery flaw that enables remote attackers to manipulate the application's behavior through crafted requests. This vulnerability resides within the fetch_remote_file function, which is designed to retrieve files from remote servers for processing within the MyBB environment. The flaw allows adversaries to potentially bypass security controls and access internal resources that should remain protected from external access.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the fetch_remote_file function. Attackers can exploit this weakness by providing malicious URLs or parameters that cause the application to make unintended requests to internal systems or external malicious servers. The vulnerability operates at the application layer and can be leveraged to perform various malicious activities including internal network scanning, data exfiltration, or even further exploitation of vulnerable internal services. This type of vulnerability is categorized under CWE-918 as Server-Side Request Forgery, which specifically addresses weaknesses where applications make HTTP requests to arbitrary destinations based on user-provided input without adequate validation.
The operational impact of CVE-2016-9417 is significant for MyBB installations, as it can lead to unauthorized access to internal network resources, potential data breaches, and escalation of privileges within the affected environment. Attackers may use this vulnerability to probe internal systems, access sensitive information, or establish persistence within the network. The vulnerability can be particularly dangerous in environments where MyBB is deployed with administrative privileges or where internal systems are not properly isolated from external access. According to ATT&CK framework, this vulnerability maps to T1071.004 for Application Layer Protocol: DNS and T1566 for Phishing, as it enables attackers to leverage the application to perform unauthorized network requests.
Organizations using affected MyBB versions should immediately implement mitigations including updating to MyBB 1.8.8 or later, which contains patches addressing this vulnerability. Additional defensive measures include implementing proper input validation for all user-supplied data, restricting outbound network access from the MyBB server, and monitoring network traffic for suspicious requests. The vulnerability demonstrates the importance of validating and sanitizing all external inputs, particularly when dealing with remote resource fetching operations, as highlighted by security best practices outlined in OWASP Top 10 and NIST cybersecurity guidelines. System administrators should also consider implementing web application firewalls to detect and block malicious requests attempting to exploit this vulnerability, as well as conducting regular security assessments to identify similar weaknesses in other components of the application stack.