CVE-2018-19201 in MyBB
Summary
by MITRE
A reflected XSS vulnerability in the ModCP Profile Editor in MyBB before 1.8.20 allows remote attackers to inject JavaScript via the 'username' parameter.
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Analysis
by VulDB Data Team • 05/23/2020
The vulnerability identified as CVE-2018-19201 represents a critical reflected cross-site scripting flaw within the ModCP Profile Editor component of MyBB forums prior to version 1.8.20. This vulnerability resides in the handling of user input parameters, specifically the 'username' field which is processed through the moderation control panel profile editor functionality. The flaw enables remote attackers to execute malicious JavaScript code within the context of a victim's browser session, potentially compromising user accounts and data confidentiality.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the ModCP Profile Editor module. When the system processes the 'username' parameter without proper sanitization, it fails to escape or encode special characters that could be interpreted as HTML or JavaScript code. This creates an environment where attacker-controlled input can be directly reflected back to users without appropriate security measures. The vulnerability is classified under CWE-79 as a Reflected Cross-Site Scripting flaw, which occurs when user-supplied data is immediately returned to users without proper validation or encoding.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with the capability to perform session hijacking, credential theft, and data exfiltration. An attacker could craft malicious URLs containing JavaScript payloads that, when clicked by an authenticated user with moderation privileges, would execute in the victim's browser context. This could lead to unauthorized access to administrative functions, modification of user profiles, or redirection to malicious sites. The attack vector is particularly dangerous because it targets the ModCP functionality, which typically requires elevated privileges, potentially allowing attackers to escalate their privileges within the forum environment.
The exploitation of this vulnerability aligns with ATT&CK technique T1531 for Establishing Persistence and T1059 for Command and Scripting Interpreter, as attackers can leverage the reflected XSS to maintain access through malicious scripts. The attack requires minimal user interaction, typically involving social engineering to convince victims to click malicious links, making it particularly effective in forum environments where users frequently interact with external links. Organizations running MyBB versions prior to 1.8.20 face significant risk of account compromise and data breaches when this vulnerability is exploited.
Mitigation strategies for CVE-2018-19201 require immediate patching of the MyBB software to version 1.8.20 or later, which includes proper input validation and output sanitization for the affected parameter. Additional defensive measures should include implementing Content Security Policy headers to restrict script execution, deploying web application firewalls to detect and block malicious payloads, and conducting regular security assessments of forum components. Organizations should also implement proper input validation at multiple layers, including client-side and server-side sanitization, and establish monitoring protocols to detect unusual activity patterns that may indicate exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date software and implementing comprehensive security controls to protect against common web application vulnerabilities.