CVE-2022-28601 in Simple 2FA Plugin
Summary
by MITRE • 05/11/2022
A Two-Factor Authentication (2FA) bypass vulnerability in "Simple 2FA Plugin for Moodle" by LMS Doctor allows remote attackers to overwrite the phone number used for confirmation via the profile.php file. Therefore, allowing them to bypass the phone verification mechanism.
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Analysis
by VulDB Data Team • 05/13/2022
The CVE-2022-28601 vulnerability represents a critical security flaw in the Simple 2FA Plugin for Moodle, a widely used authentication solution in educational institutions. This vulnerability specifically targets the two-factor authentication mechanism that is designed to enhance security by requiring users to verify their identity through a second factor beyond their password. The flaw exists within the plugin's handling of user profile modifications, creating a pathway for malicious actors to manipulate the verification process. The vulnerability's severity stems from its ability to completely bypass the intended security controls that protect against unauthorized access to user accounts. Attackers can exploit this weakness to gain unauthorized access to user accounts by simply overwriting the phone number field in the profile.php file, effectively circumventing the phone-based verification mechanism that should prevent unauthorized account access.
The technical implementation of this vulnerability involves a lack of proper input validation and authorization checks within the profile modification functionality of the Moodle plugin. When users attempt to update their profile information, particularly the phone number field used for 2FA confirmation, the system fails to properly validate whether the requesting user has legitimate authorization to modify these specific fields. This represents a classic case of insufficient access control, which aligns with CWE-285, an issue that occurs when an application does not properly enforce access control mechanisms. The vulnerability allows remote attackers to craft malicious requests that manipulate the phone number field in the profile.php file, effectively enabling them to register any phone number they choose for verification purposes. This flaw particularly affects the authentication flow where users must confirm their phone numbers to complete the 2FA setup process, creating a direct path to account compromise.
The operational impact of this vulnerability extends beyond individual account compromise to potentially affect entire institutional security infrastructures. Educational institutions relying on Moodle for their learning management systems face significant risk when this vulnerability is exploited, as attackers can bypass the additional security layer that should protect against unauthorized access. The vulnerability's remote exploitability means that attackers do not need physical access to systems or network proximity to carry out attacks, making it particularly dangerous in environments where Moodle is deployed across multiple locations or accessed through various network connections. This weakness undermines the fundamental security principle of multi-factor authentication, which is designed to provide defense in depth against credential theft and unauthorized access attempts. The vulnerability also creates potential for privilege escalation and lateral movement within the institution's network, as compromised user accounts may provide access to additional resources that are protected by the same authentication mechanisms.
Mitigation strategies for CVE-2022-28601 should focus on immediate patching of the affected plugin, as the vendor has likely released updates addressing this specific vulnerability. Organizations should implement additional monitoring of profile modification activities, particularly those involving phone number changes, to detect potential exploitation attempts. Network segmentation and access control measures should be strengthened to limit the potential impact of compromised accounts. The vulnerability highlights the importance of proper input validation and authorization checks, which aligns with ATT&CK technique T1078.004 for Valid Accounts and T1566.001 for Phishing. Security teams should also consider implementing additional layers of authentication verification and regularly auditing user profile modifications to identify anomalous patterns that might indicate exploitation attempts. Organizations should ensure that their security monitoring systems are configured to alert on unusual profile changes, particularly those involving authentication-related fields, to provide early detection of potential exploitation attempts.