Security Bulletin: IBM HTTP Server CPU utilization (CVE-2014-0963)

Summary

IBM HTTP Server is affected by a problem related to the SSL implementation which, under very specific conditions, can cause CPU utilization to rapidly increase.

Vulnerability Details

CVE ID: CVE-2014-0963

DESCRIPTION:
IBM HTTP Server is affected by a problem with the handling of certain SSL messages. The TLS implementation can, under very specific conditions, cause CPU utilization to rapidly increase. The situation occurs only in a certain error case that causes a single thread to begin looping. If this happens multiple times, more threads will begin to loop and an increase in CPU utilization will be seen. This increase could ultimately result in CPU exhaustion and unresponsiveness of the IBM HTTP Server and other software running on the affected system.

This issue can affect the availability of the system, but does not impact system confidentiality or integrity. This vulnerability can be remotely exploited, authentication is not required and the exploit is moderately complex.

To determine if your systems are being affected by this issue, you can monitor the CPU utilization for IBM HTTP Server instances, or monitor the mod_mpmstats output written to the ErrorLog.

CVSS Base Score: 7.1
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/92844 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:N/A:C)

Affected Products and Versions

This problem affects the IBM HTTP Server component in all editions of WebSphere Application Server and bundling products:
· Version 8.5.5
· Version 8.5
· Version 7.0
· Version 6.1
· Version 6.0

Remediation/Fixes

The recommended solutions is to apply the interim fix, Fix Pack or PTF containing APAR PI17025 for each named product as soon as practical

For affected IBM HTTP Server for WebSphere Application Server:

For V8.5.0.0 through 8.5.5.2 Full Profile:

· Apply Interim Fix PI17025

--OR–

· Apply Fix Pack 8.5.5.3 or later.

**
For V8.0 through 8.0.0.8:**

· Apply Interim Fix PI17025

--OR–

· Apply Fix Pack 8.0.0.9 or later.

For V7.0.0.0 through 7.0.0.31:

· Apply Interim Fix PI17025

--OR–

· Apply Fix Pack 7.0.0.33 or later.

For V6.1.0.0 through 6.1.0.47:

· Apply Interim Fix PI17025

**
For V6.0.0.0 through 6.0.2.43:**

· Apply Interim Fix PI17025

Workarounds and Mitigations

Use any of these workarounds:

• For Any Release:
  • Disable_ mod_reqtimeout_ by commenting out both the line beginning with “LoadModule reqtimeout_module…” in httpd.conf and any line beginning with “RequestReadTimeout”. Note: This is not intuitive, but CVE-2014-0963 does not manifest in IBM HTTP Server without mod_reqtimeout also loaded.
  • Configure very short thresholds with mod_reqtimeout, which shortens the amount of time a thread can be tied up by CVE-2014-0963. See the RequestReadTimeout directive.
• • Monitor CPU utilization of your IBM HTTP Server instances. If utilization becomes abnormally high, stop and restart the affected instance.
• • Monitor mod_mpmstats output for unusual build-up of threads with active module “mod_ibm_ssl"