Vulnerability Note VU#467828

Mac OS X LDAP plugins transmit user credentials in clear text

Overview

Versions 10.2 and later of Apple's MacOS X operating system include support for the Lightweight Directory Access Protocol (LDAP). A vulnerability in the way some of these versions of MacOS X handle authentication in certain environments could expose user's passwords in plaintext as they're transmitted across the network.

I. Description

Client systems using Kerberos login passwords and integration with an LDAP server may inadvertently send the account password over the network to the LDAP server in clear text format. If the "authentication authority" attribute is not set on the LDAP server, the loginwindow application will try to authenticate the account to the configured LDAP server. After trying to authenticate the user with an encrypted password, the loginwindow application falls back to trying a Bind using an AuthenticationChoice of simple on the server. This fallback action causes the account password to be transmitted over the network in clear text.

This vulnerability is exposed strictly in an environment where clients are configured to use Kerberos for authentication and LDAP for lookup of other user records. This configuration is not the default for MacOS X, but is commonly recommended and used for environments with a large userbase.

II. Impact

An attacker who has the ability to sniff packets as they cross the network or has access to logs on the LDAP servers can acquire the plaintext passwords of users authenticating to the Kerberos system. The attacker could subsequently use these passwords to impersonate the corresponding users and gain the privileges of that principle in the Kerberos realm.

III. Solution

Patches and workarounds are available for this vulnerability. Please see the vendors section of this document for more details.

Sites may also wish to enable Secure Sockets Layer (SSL) connectivity to LDAP servers in order to prevent other sensitive information that may be exchanged during the LDAP session from being passed over the network in cleartext.

Systems Affected

Vendor	Status	Date Notified	Date Updated
Apple Computer Inc.	Vulnerable	23-Jun-2003

References

http://docs.info.apple.com/article.html?artnum=107579
http://www.secunia.com/advisories/8945/
http://securitytracker.com/alerts/2003/Jun/1006922.html

Credit

Thanks to Patrick M McNeal for reporting this vulnerability.

This document was written by Chad R Dougherty.

Other Information

Date Public:	2003-05-27
Date First Published:	2003-06-04
Date Last Updated:	2003-06-23
CERT Advisory:
CVE-ID(s):	CAN-2003-0378
NVD-ID(s):	CAN-2003-0378
US-CERT Technical Alerts:
Severity Metric:	7.76
Document Revision:	16

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