pam_ldap and nss_ldap: Plain text authentication leak

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200507-13 / pam_ldap nss_ldap
Release Date	July 14, 2005
Latest Revision	July 14, 2005: 01
Impact	normal
Exploitable	remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
sys-auth/nss_ldap	< 239-r1	>= 239-r1, revision >= 226-r1	All supported architectures
sys-auth/pam_ldap	< 178-r1	>= 178-r1	All supported architectures

Related bugreports: #96767

Synopsis

pam_ldap and nss_ldap fail to restart TLS when following a referral, possibly leading to credentials being sent in plain text.

2. Impact Information

Background

pam_ldap is a Pluggable Authentication Module which allows authentication against an LDAP directory. nss_ldap is a Name Service Switch module which allows 'passwd', 'group' and 'host' database information to be pulled from LDAP. TLS is Transport Layer Security, a protocol that allows encryption of network communications.

Description

Rob Holland of the Gentoo Security Audit Team discovered that pam_ldap and nss_ldap fail to use TLS for referred connections if they are referred to a master after connecting to a slave, regardless of the "ssl start_tls" ldap.conf setting.

Impact

An attacker could sniff passwords or other sensitive information as the communication is not encrypted.

3. Resolution Information

Workaround

pam_ldap and nss_ldap can be set to force the use of SSL instead of TLS.

Resolution

All pam_ldap users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-auth/pam_ldap-178-r1"

All nss_ldap users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose sys-auth/nss_ldap

4. References

CAN-2005-2069

Updated July 14, 2005

Summary: This is a Gentoo Linux Security Advisory

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