CVE-2018-15833 in Vanilla
Summary
by MITRE
In Vanilla before 2.6.1, the polling functionality allows Insecure Direct Object Reference (IDOR) via the Poll ID, leading to the ability of a single user to select multiple Poll Options (e.g., vote for multiple items).
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Analysis
by VulDB Data Team • 03/18/2020
The vulnerability described in CVE-2018-15833 represents a critical Insecure Direct Object Reference flaw within the Vanilla forum platform prior to version 2.6.1. This security weakness specifically affects the polling functionality where users can manipulate the Poll ID parameter to access and interact with polls they should not have authorization to modify. The issue stems from inadequate input validation and access control mechanisms that fail to properly verify user permissions before processing polling operations. When a user attempts to vote on a poll, the system relies on the Poll ID parameter to determine which poll to modify, but this parameter can be easily manipulated by unauthorized users to target different polls within the system.
The technical implementation of this vulnerability allows attackers to exploit the lack of proper authorization checks during the polling process. In Vanilla versions before 2.6.1, the application does not validate whether the authenticated user has legitimate access rights to the specific poll they are attempting to modify. This creates an environment where any authenticated user can submit requests targeting different Poll IDs, effectively enabling them to cast votes on multiple polls simultaneously or manipulate poll results. The flaw operates at the application logic level where the system assumes that the Poll ID parameter represents a legitimate target without verifying the relationship between the user and the poll resource. This represents a classic IDOR vulnerability pattern where the application exposes internal object references without proper access controls.
The operational impact of this vulnerability extends beyond simple voting manipulation to potentially compromise the integrity of polling systems within the Vanilla platform. An attacker could systematically vote on multiple polls to skew results, create false representations of community sentiment, or manipulate the outcomes of important decisions made through polling mechanisms. The vulnerability affects all authenticated users who can access the polling functionality, meaning that even legitimate users with normal privileges could exploit this weakness to gain unauthorized access to poll manipulation capabilities. This type of vulnerability undermines the trustworthiness of polling data and can lead to significant reputational damage for organizations relying on Vanilla forums for community engagement and decision-making processes. The flaw essentially allows for vote manipulation at scale, where a single user could potentially influence multiple poll outcomes through simple parameter modification.
Security mitigations for this vulnerability should focus on implementing proper access control validation mechanisms that verify user authorization before processing any poll modifications. The recommended approach involves implementing robust input validation that checks the relationship between the authenticated user and the target poll resource before allowing any voting operations. Organizations should ensure that all poll-related operations require proper authorization checks that validate the user's legitimate access rights to the specific poll they are attempting to modify. This includes implementing proper session management, enforcing role-based access controls, and validating that the Poll ID parameter corresponds to a poll that the user is authorized to access or modify. The fix should be implemented as part of a comprehensive security review of the application's resource access controls and should be validated through penetration testing to ensure that similar vulnerabilities do not exist in other parts of the application. This vulnerability aligns with CWE-284 Access Control Issues and represents a violation of the principle of least privilege that should be addressed through proper authorization mechanisms. The ATT&CK framework would categorize this as a privilege escalation technique through insecure direct object references, where an attacker leverages weak access controls to gain unauthorized access to additional resources within the application.