CVE-2015-7436 in Cognos Business Intelligence
Summary
by MITRE
IBM Tivoli Common Reporting (TCR) 2.1 before IF14, 2.1.1 before IF22, 2.1.1.2 before IF9, 3.1.0.0 through 3.1.2 as used in Cognos Business Intelligence before 10.2 IF16, and 3.1.2.1 as used in Cognos Business Intelligence before 10.2.1.1 IF12 preserves user permissions across group-add and group-remove operations, which allows local users to bypass intended access restrictions in opportunistic circumstances by leveraging administrative changes to group membership.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/26/2018
The vulnerability identified as CVE-2015-7436 affects IBM Tivoli Common Reporting and its integration with Cognos Business Intelligence platforms, representing a significant access control flaw that undermines the security model of these enterprise reporting systems. This issue stems from improper handling of user permissions during group membership modifications, creating a persistent security weakness that can be exploited by local attackers to gain unauthorized access to restricted resources. The vulnerability impacts multiple versions including TCR 2.1 before IF14, 2.1.1 before IF22, 2.1.1.2 before IF9, and various iterations of Cognos Business Intelligence up to specific interim fixes, indicating a widespread exposure across the product lifecycle.
The technical flaw manifests when administrative changes occur to group membership within the system, specifically during group-add and group-remove operations. Normally, when users are added to or removed from groups, their access permissions should be recalculated and enforced according to the new group memberships. However, this vulnerability causes the system to preserve existing user permissions across these operations, effectively maintaining access rights that should have been revoked when users were removed from groups or that should have been granted when they were added. This behavior creates a scenario where users can maintain access to resources they should no longer be able to access, particularly when group membership changes occur in a specific sequence or timing that allows the preserved permissions to be leveraged.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it creates opportunities for privilege escalation and data exposure that can significantly compromise enterprise security. Local users who can manipulate group membership changes can exploit this weakness to bypass intended access restrictions, potentially gaining access to sensitive reports, data sets, or administrative functions that should be restricted to specific user groups. This vulnerability particularly affects organizations that rely heavily on group-based access control mechanisms, as it undermines the fundamental security principle that access rights should be dynamically adjusted according to current group memberships. The opportunistic nature of the exploit means that the vulnerability may not be immediately apparent, as it depends on specific timing and sequence of administrative operations, making it particularly challenging to detect and remediate.
Organizations should implement immediate mitigations including applying the vendor-provided patches and interim fixes for the affected versions of IBM Tivoli Common Reporting and Cognos Business Intelligence. System administrators should conduct comprehensive audits of group membership configurations and access permissions to identify any potential exploitation that may have occurred. The vulnerability aligns with CWE-284, which describes improper access control, and can be mapped to ATT&CK technique T1078 for valid accounts and T1484 for domain policy modification, as it enables unauthorized access through manipulated group membership. Additionally, organizations should consider implementing additional monitoring controls to detect unusual group membership changes and access patterns that could indicate exploitation attempts. Regular security assessments and privilege reviews should be conducted to ensure that access controls remain properly enforced across all reporting and business intelligence platforms.