Security Bulletin: Information Disclosure vulnerability affects IBM® DB2® LUW (CVE-2017-1150)

Summary

When a table is renamed and a new table is created with the old name, users who had access on the old table may be able to access the new table.

Vulnerability Details

A user may incorrectly acquire privileges on a table if the table is created with the same name as a previously renamed table. During a RENAME TABLE, a user maintains privileges on the renamed table. However, if a new table is then created with the old name, the user may also incorrectly maintain their privileges on this new table. The problem is caused by the rename operation not updating the user authorization cache. The error will be cleared up when the database is deactivated or when the DB2 instance is restarted.

For example:
User A is granted select privilege to table ABC.T1
An authorized user renames table ABC.T1 to ABC.T2
An authorized user creates a new table called ABC.T1
User A can correctly select from ABC.T2 (the new name for the renamed table) but will incorrectly gain the ability to select from ABC.T1 (new table)

CVEID: CVE-2017-1150**
DESCRIPTION: *IBM DB2 for Linux, UNIX and Windows (includes DB2 Connect Server) could allow an authenticated attacker with specialized access to tables that they should not be permitted to view.
CVSS Base Score: 3.1
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/122291 for the current score
CVSS Environmental Score: Undefined
CVSS Vector: (CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N)

Affected Products and Versions

All fix pack levels of IBM DB2 V10.1, V10.5 and V11.1 editions listed below and running on AIX, Linux, HP, Solaris or Windows are affected:

IBM® DB2® Express Edition
IBM® DB2® Workgroup Server Edition
IBM® DB2® Enterprise Server Edition
IBM® DB2® Advanced Enterprise Server Edition
IBM® DB2® Advanced Workgroup Server Edition
IBM® DB2® Direct Advanced Edition
IBM® DB2® Direct Standard Edition
IBM® DB2® Connect™ Application Server Edition
IBM® DB2® Connect™ Enterprise Edition
IBM® DB2® Connect™ Unlimited Edition for System i®
IBM® DB2® Connect™ Unlimited Edition for System z®

The DB2 Connect products mentioned are affected only if a local database has been created.

Remediation/Fixes

The recommended solution is to apply the appropriate fix for this vulnerability.

FIX:

The fix for DB2 and DB2 Connect release is in V10.1 FP6 is available for download from Fix Central.

Customers running any vulnerable fixpack level of an affected Program, V10.5 and V11.1 can download the special build containing the interim fix for this issue from Fix Central. These special builds are available based on the most recent fixpack level for each impacted release: DB2 V10.5 FP8 and DB2 V11.1.1 FP1. They can be applied to any affected fixpack level of the appropriate release to remediate this vulnerability.

Workarounds and Mitigations

Workaround #1
Recycling the database:

• db2stop
• db2start
• Workaround #2

1. Create a new table with the old table name.
   For each affected grantee:
2. Grant the privilege(s) held by the grantee on the old table.
3. Revoke the granted privilege(s) from step a.
4. Drop the table created on step 1 (if not needed anymore).

Workaround #3
Revoke all the privileges from other grantees prior to the RENAME TABLE and re-grant the privileges to the grantees on the newly named table.