Bugzilla – Bug 105118
VUL-0: CVE-2005-2641: pam_ldap password policy vulnerability
Last modified: 2021-11-21 15:36:24 UTC
This came in from Luke Howare <lukeh@padl.com>: When the new password policy control is in use, a DSA that returns the control on bind failure where there is no password policy error will cause pam_ldap to allow the user to logon anyway.
Here is some more information that came in yesterday: CONTACT INFORMATION =============================================================================== Let us know who you are: Name : Luke Howard E-mail : lukeh@padl.com Phone / fax : +61 3 9671 3515 / 3517 Affiliation and address: PADL Software Pty Ltd Have you reported this to the vendor? [yes/no] Yes If so, please let us know whom you've contacted: Date of your report : 08/16 Vendor contact name : Luke Howard Vendor contact phone : +61 3 9671 3515 Vendor contact e-mail : lukeh@padl.com Vendor reference number : If not, we encourage you to do so--vendors need to hear about vulnerabilities from you as a customer. POLICY INFO =============================================================================== We encourage communication between vendors and their customers. When we forward a report to the vendor, we include the reporter's name and contact information unless you let us know otherwise. If you want this report to remain anonymous, please check here: ___ Do not release my identity to your vendor contact. TECHNICAL INFO =============================================================================== If there is a CERT Vulnerability tracking number please put it here (otherwise leave blank): VU#______. Please describe the vulnerability. - ---------------------------------- This vulnerability was introduced in pam_ldap-169, which included preliminary support for draft-behera-ldap-password-policy-07.txt. If a pam_ldap client authenticates against an LDAP server that returns a passwordPolicyResponse control, but omits the optional "error" field of the PasswordPolicyResponseValue, then the LDAP authentication result will be ignored and the authentication step will always succeed. While any password policy error should be propagated to the account management (authorization) step, under no circumstance should the absence of the error field override the BindResponse resultCode. A fix that corrects this will be available in pam_ldap-180, available from www.padl.com/OSS/pam_ldap.html. What is the impact of this vulnerability? - ----------------------------------------- (For example: local user can gain root/privileged access, intruders can create root-owned files, denial of service attack, etc.) a) What is the specific impact: When pam_ldap is configured against a directory server that returns the passwordPolicyResponse control in a BindResponse with no error field, any user will be allowed to logon to the local system, regardless of whether the underlying BindRequest succeeded. This behaviour is likely to occur consistently, so one would expect it to be noticed during the provisioning of the pam_ldap module. b) How would you envision it being used in an attack scenario: One could exploit this by removing the error field from the encoded passwordPolicyResponse on the wire if integrity protection is not used on the underlying LDAP connection. However, this would be contrary to the best practices for deploying pam_ldap (integrity and confidentiality should be used). If integrity and confidentiality protection are not used, then more trivial MITM attacks exist. Otherwise, a competent system administrator deploying pam_ldap with an LDAP server that triggers this vulnerability would likely notice that all logons succeed during the initial configuration of the software. The only potentially dangerous exploit would be if it were possible for a legitimate client authentication to trigger the omission of the error field in the passwordPolicyResponse in a manner which is unlikely to be noticed by an administrator during the initial configuration of the software. To your knowledge is the vulnerability currently being exploited? - ----------------------------------------------------------------- [yes/no] I'm not aware of any exploits; as mentioned above, one would expect to have notice this during provisioning. We have only seen the vulnerability triggered when pam_ldap is used with the OpenLDAP password policy module. (The contributor of this functionality tested with a directory server that did not trigger the issue.) If there is an exploitation script available, please include it here. - --------------------------------------------------------------------- N/A Do you know what systems and/or configurations are vulnerable? - -------------------------------------------------------------- [yes/no] (If yes, please list them below) This vulnerability applies to all versions of pam_ldap since 169, on all platforms (unless the underlying LDAP client library does not support LDAPv3 controls, in which case the functionality would be disabled). pam_ldap is shipped with popular Linux distributions, including Red Hat and SuSE, as well as SGI IRIX. I have no information as to which vendors, if any, ship versions of pam_ldap that are vulnerable.
Created attachment 46248 [details] Proposed fix This patch contains a fix for the problem. Proposed by Luke Howard.
Submitted fixed package to STABLE.
Ok. fix in STABLE is sufficient. closing.
CVE-2005-2641
CVE-2005-2641: CVSS v2 Base Score: 7.5 (AV:N/AC:L/Au:N/C:P/I:P/A:P)