MITKRB5-SA-2011-006 KDC denial of service vulnerabilities [CVE-2011-1527 CVE-2011-1528 CVE-2011-1529]

2011-10-24T00:00:00
ID SECURITYVULNS:DOC:27181
Type securityvulns
Reporter Securityvulns
Modified 2011-10-24T00:00:00

Description

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MITKRB5-SA-2011-006

MIT krb5 Security Advisory 2011-006 Original release: 2011-10-18 Last update: 2011-10-18

Topic: KDC denial of service vulnerabilities

CVE-2011-1527: null pointer dereference in KDC LDAP back end

CVSSv2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:C/E:H/RL:OF/RC:C

CVSSv2 Base Score: 7.8

Access Vector: Network Access Complexity: Low Authentication: None Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete

CVSSv2 Temporal Score: 6.8

Exploitability: High Remediation Level: Official Fix Report Confidence: Confirmed

CVE-2011-1528: assertion failure in multiple KDC back ends

CVSSv2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:C/E:POC/RL:OF/RC:C CVSSv2 Base Score: 7.8 CVSSv2 Temporal Score: 6.1

CVE-2011-1529: null pointer dereference in multiple KDC back ends

CVSSv2 Vector: AV:N/AC:L/Au:N/C:N/I:N/A:C/E:POC/RL:OF/RC:C CVSSv2 Base Score: 7.8 CVSSv2 Temporal Score: 6.1

SUMMARY

CVE-2011-1527: In releases krb5-1.9 and later, the KDC can crash due to a null pointer dereference if configured to use the LDAP back end. A trigger condition is publicly known but not known to be widely circulated.

CVE-2011-1528: In releases krb5-1.8 and later, the KDC can crash due to an assertion failure. No exploit is known to exist, but there is public evidence that the unidentified trigger condition occurs in the field.

CVE-2011-1529: In releases krb5-1.8 and later, the KDC can crash due to a null pointer dereference. No exploit is known to exist.

IMPACT

CVE-2011-1527: An unauthenticated remote attacker can crash a KDC daemon via null pointer dereference if the KDC is configured to use the LDAP back end. (This is not the default configuration.)

CVE-2011-1528: An unauthenticated remote attacker can crash a KDC daemon via assertion failure.

CVE-2011-1529: An unauthenticated remote attacker can crash a KDC daemon via null pointer dereference.

AFFECTED SOFTWARE

  • The KDC in krb5-1.9 and later is vulnerable to CVE-2011-1527 when configured with the LDAP back end. Earlier releases had different code that masked this bug and did not crash under these conditions.

  • The KDC in krb5-1.8 and later is vulnerable to CVE-2011-1528 when configured with the LDAP back end. When configured with the Berkeley DB ("db2") back end, only releases krb5-1.8 through krb5-1.8.4 are vulnerable.

  • The KDC in krb5-1.8 and later is vulnerable to CVE-2011-1529 when configured with either the Berkeley DB ("db2") or the LDAP back end.

FIXES

  • Workaround: restart the KDC when it crashes, possibly using an automated monitoring process.

  • An upcoming release in the krb5-1.9.x series will fix CVE-2011-1527.

  • Upcoming releases in the krb5-1.8.x and krb5-1.9.x series will fix CVE-2011-1528 and CVE-2011-1529.

  • The patch for krb5-1.9.x is available at

http://web.mit.edu/kerberos/advisories/2011-006-patch.txt

A PGP-signed patch is available at

http://web.mit.edu/kerberos/advisories/2011-006-patch.txt.asc

  • The patch for krb5-1.8.x is available at

http://web.mit.edu/kerberos/advisories/2011-006-patch-r18.txt

A PGP-signed patch is available at

http://web.mit.edu/kerberos/advisories/2011-006-patch-r18.txt.asc

REFERENCES

This announcement is posted at:

http://web.mit.edu/kerberos/advisories/MITKRB5-SA-2011-006.txt

This announcement and related security advisories may be found on the MIT Kerberos security advisory page at:

    http://web.mit.edu/kerberos/advisories/index.html

The main MIT Kerberos web page is at:

    http://web.mit.edu/kerberos/index.html

CVSSv2:

http://www.first.org/cvss/cvss-guide.html
http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2

CVE: CVE-2011-1527 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1527

CVE: CVE-2011-1528 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1528

CVE: CVE-2011-1529 http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2011-1529

Debian bug #629558: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=629558

Ubuntu bug #715579: https://bugs.launchpad.net/ubuntu/+source/krb5/+bug/715579

ACKNOWLEDGMENTS

CVE-2011-1527: Nalin Dahyabhai and Andrej Ota independently reported this vulnerability. Kyle Moffett independently reported this bug to Debian.

CVE-2011-1528: Mark Deneen reported this vulnerability to Ubuntu.

CONTACT

The MIT Kerberos Team security contact address is <krbcore-security@mit.edu>. When sending sensitive information, please PGP-encrypt it using the following key:

pub 2048R/56CD8F76 2010-12-29 [expires: 2012-02-01] uid MIT Kerberos Team Security Contact <krbcore-security@mit.edu>

DETAILS

CVE-2011-1527: null pointer dereference in KDC LDAP back end

Under certain error conditions, krb5_ldap_get_principal() in the KDC LDAP back end can return success yet leave the client principal entry as a null pointer. Subsequently executed code attempts to dereference this null pointer.

CVE-2011-1528: assertion failure in multiple KDC back ends

In the KDC LDAP back end in releases krb5-1.8 and later, krb5_ldap_lockout_audit() calls assert() with an expression that could be false under as-yet unidentified conditions. A similar problem occurs in the KDC Berkeley DB ("db2") back end in krb5_db2_lockout_audit() in releases krb5-1.8 through krb5-1.8.4. (The db2 back end no longer has this assertion in releases krb5-1.9 and later, and is therefore not vulnerable.) There is a report that the assertion failure occurs in the field, but there is insufficient information to identify the actual vector.

CVE-2011-1529: null pointer dereference in multiple KDC back ends

In releases krb5-1.8 and later, lookup_lockout_policy() in both the Berkeley DB ("db2") and LDAP KDC back ends fails to check that the principal entry pointer is non-null prior to dereferencing it. This can happen if an error condition such as KRB5KDC_ERR_PREAUTH_FAILED or KRB5KRB_AP_ERR_BAD_INTEGRITY occurs in process_as_req() before it retrieves the principal database entry for the requested client.

REVISION HISTORY

2011-10-18 original release

Copyright (C) 2011 Massachusetts Institute of Technology -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.8 (SunOS)

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