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.

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.

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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.

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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.

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Vendor Information

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Apple Computer Inc. __ Affected

Notified: May 19, 2003 Updated: June 23, 2003

Status

Affected

Vendor Statement

Apple: This is fixed in Security Update 2003-06-09 which is available as a free download from: ``<http://docs.info.apple.com/article.html?artnum=120223>``

Further information, including a workaround for previous versions, is available in the AppleCare Knowledge Base at ``<http://docs.info.apple.com/article.html?artnum=107579>`` "How to Avoid Sending Clear Passwords in a Kerberos Environment With LDAPv3."

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23467828 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

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

Acknowledgements

Thanks to Patrick M McNeal for reporting this vulnerability.

This document was written by Chad R Dougherty.

Other Information

CVE IDs:	CVE-2003-0378
Severity Metric:	7.76 Date Public: