Security Bulletin: Vulnerability in RC4 stream cipher affects Rational Directory Server (CVE-2015-2808)

Summary

The RC4 “Bar Mitzvah” Attack for SSL/TLS affects IBM Rational Directory Server and Administrator.

Vulnerability Details

CVEID: CVE-2015-2808 DESCRIPTION: The RC4 algorithm, as used in the TLS protocol and SSL protocol, could allow a remote attacker to obtain sensitive information. An attacker could exploit this vulnerability to remotely expose account credentials without requiring an active man-in-the-middle session. Successful exploitation could allow an attacker to retrieve credit card data or other sensitive information. This vulnerability is commonly referred to as “Bar Mitzvah Attack”.
CVSS Base Score: 5
CVSS Temporal Score: See https://exchange.xforce.ibmcloud.com/vulnerabilities/101851 for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:L/Au:N/C:P/I:N/A:N)

Affected Products and Versions

Product

| Version
—|—
Rational Directory Server (Tivoli) | 5.2 - 5.2.1_iFix006
Rational Directory Server (Apache)| 5.1.1 - 5.1.1.2_iFix007

Remediation/Fixes

NOTE: You should verify applying this fix does not cause any compatibility issues. The fix disables RC4 stream cipher by default. If you change this setting you will expose yourself to the attack described above. IBM recommends that you review your entire environment to identify other areas where you have enabled the RC4 stream cipher and take appropriate mitigation and remediation actions.

_For Rational Directory Server and Administrator, versions prior to 5.2 (Tivoli) and 5.1.1 (Apache) _IBM recommends upgrading to supported version of the product.

Workarounds and Mitigations

For IBM Tivoli Directory Server, certain configuration changes are required to mitigate this issue.

1. Go to the tdsadminInstance folder

a. For Windows based system: Go to folder location C:\idsslapd-tdsadmin\etc

b. For UNIX based system: Go to folder location <RDS Install Location>/Instance/idsslapd-tdsadmin/etc
2. Take a backup of the file ibmslapd.conf

3. Open the file for editing.

4. Search for ibm-slapdSslCipherSpec

5. Under this attribute, comment all ciphers that start with RC4. Your sample ibmslapd.confshould look like this

#ibm-slapdSslCipherSpec: RC4-128-MD5

#ibm-slapdSslCipherSpec: RC4-128-SHA

ibm-slapdSslCipherSpec: AES

ibm-slapdSslCipherSpec: AES-128

ibm-slapdSslCipherSpec: TripleDES-168

ibm-slapdSslCipherSpec: DES-56

#ibm-slapdSslCipherSpec: RC4-40-MD5

#ibm-slapdSslCipherSpec: RC2-40-MD5

You should verify applying this configuration change does not cause any compatibility issues. Not disabling the RC4 stream cipher will expose yourself to the attack described above. IBM recommends that you review your entire environment to identify other areas where you have enabled the RC4 stream cipher and take appropriate mitigation and remediation actions.