CVE-2017-9551 in Mahara
Summary
by MITRE
Mahara 15.04 before 15.04.14 and 16.04 before 16.04.8 and 16.10 before 16.10.5 and 17.04 before 17.04.3 are vulnerable to a user submitting potential dangerous payload, e.g. XSS code, to be saved as their name in the usr_registration table. The values are then emailed to the the user and administrator and if accepted become part of the new user's account.
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Analysis
by VulDB Data Team • 11/19/2019
The vulnerability identified as CVE-2017-9551 affects the Mahara learning management system version 15.04 before 15.04.14 and 16.04 before 16.04.8 and 16.10 before 16.10.5 and 17.04 before 17.04.3. This represents a critical security flaw that allows authenticated users to inject malicious payloads into their user registration information, specifically within the usr_registration table. The vulnerability stems from inadequate input validation and sanitization mechanisms that fail to properly filter or escape user-supplied data before it is stored in the database and subsequently processed for email notifications. The flaw manifests when users can submit potentially dangerous content such as cross-site scripting (XSS) code as part of their registration name field, which then gets stored and later transmitted through email communications to both the user and system administrators.
The technical implementation of this vulnerability resides in the insufficient sanitization of user input within the registration process, which directly maps to CWE-79 - Cross-site Scripting. The system fails to properly validate and escape user-provided data before it is stored in the usr_registration table, creating a persistent XSS vulnerability that can be exploited through the email delivery mechanism. When the registration information is emailed to both users and administrators, any malicious scripts embedded in the name field execute in the context of the recipient's browser, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability is particularly dangerous because it operates through legitimate system processes, making detection more challenging as the malicious payloads are delivered through normal email communications rather than direct attack vectors.
The operational impact of this vulnerability extends beyond simple XSS exploitation, as it can be leveraged to compromise entire user sessions and potentially gain unauthorized access to administrative functions. Attackers can craft malicious payloads that, when executed in the context of an administrator's browser, could lead to privilege escalation or unauthorized modifications to user accounts. The vulnerability affects the core registration functionality of Mahara, potentially compromising the integrity of user data and system security. Additionally, the email delivery mechanism creates a vector for social engineering attacks where administrators might unknowingly execute malicious code simply by opening registration emails. The vulnerability also impacts the system's trust model, as any user can potentially compromise the security of other users through the registration process, violating the principle of least privilege and potentially enabling broader system compromise.
Mitigation strategies for CVE-2017-9551 require immediate implementation of proper input validation and output encoding mechanisms throughout the registration process. Organizations should implement comprehensive sanitization of all user input fields, particularly those that are subsequently displayed or emailed to other users, following the principles outlined in the OWASP Input Validation and Output Encoding guidelines. The system should employ strict validation of user-supplied data against known safe character sets and implement proper HTML escaping for all output contexts, particularly email communications. Updates to the affected Mahara versions are essential, with administrators upgrading to the patched versions 15.04.14, 16.04.8, 16.10.5, and 17.04.3 respectively. Additionally, security monitoring should be enhanced to detect anomalous registration patterns and potential exploitation attempts, while implementing content security policies to prevent execution of unauthorized scripts in email clients. The vulnerability also highlights the importance of principle of least privilege in system design, where user input should never be trusted without proper sanitization, aligning with ATT&CK technique T1059.007 - Command and Scripting Interpreter: PowerShell and broader defensive strategies for preventing data injection attacks.