Kerberos 5 Release 1.8.4

• Announcement
• README file
• Known Bugs
• Documentation
• Retrieving

Kerberos 5 Release 1.8.4 is now available

The MIT Kerberos Team announces the availability of the krb5-1.8.4 release. The detached PGP signature is available without going through the download page, if you wish to verify the authenticity of a distribution you have obtained elsewhere.

Please see the README file for a more complete list of changes.

You may also see the current full list of fixed bugs tracked in our RT bugtracking system.

DES transition

The Data Encryption Standard (DES) is widely recognized as weak. The krb5-1.7 release contains measures to encourage sites to migrate away from using single-DES cryptosystems. Among these is a configuration variable that enables "weak" enctypes, which now defaults to "false" beginning with krb5-1.8. The krb5-1.8 release includes additional measures to ease the transition away from single-DES. These additional measures include:

• enctype config enhancements (so you can do "DEFAULT +des", etc.)
• new API to allow applications (e.g. AFS) to explicitly reenable weak crypto
• easier kadmin history key changes

Major changes in 1.8.4

• Fix vulnerabilities:
  • KDC uninitialized pointer crash [MITKRB5-SA-2010-006 CVE-2010-1322]
  • kpropd denial of service [MITKRB5-SA-2011-001 CVE-2010-4022]
  • KDC denial of service attacks [MITKRB5-SA-2011-002 CVE-2011-0281 CVE-2011-0282 CVE-2011-0283]
  • KDC double-free when PKINIT enabled [MITKRB5-SA-2011-003 CVE-2011-0284]
  • kadmind frees invalid pointer [MITKRB5-SA-2011-004 CVE-2011-0285]
• Interoperability:
  • Correctly encrypt GSSAPI forwarded credentials using the session key, not a subkey.
  • Set NT-SRV-INST on TGS principal names as expected by some Windows Server Domain Controllers.
  • Don't reject AP-REQ messages if their PAC doesn't validate; suppress the PAC instead.
  • Correctly validate HMAC-MD5 checksums that use DES keys

Major changes in 1.8.3

• Behavior Change:

  GSS-API context expiration -- the gss_wrap and gss_unwrap functions no longer check for ticket expiration. Applications wishing to enforce ticket lifetimes should check using the gss_inquire_context function. The previous behavior of checking for ticket expiration produced results that were not expected by application developers, and could lead to poor user experience.

• Fix an interoperability issue when the Microsoft HMAC-MD5 checksum type was used with non-RC4 keys.
• Fix an interoperability issue with ephemeral Diffie-Hellman key exchange in PKINIT that would happen for less than 1% of transactions.

Major changes in 1.8.2

This is primarily a bugfix release.

• Fix vulnerabilities:
  • CVE-2010-1320 KDC double free caused by ticket renewal (MITKRB5-SA-2010-004)
  • CVE-2010-1321 GSS-API lib null pointer deref (MITKRB5-SA-2010-005)
• Allow numeric IPv6 addresses for configuring KDC locations.

Major changes in 1.8.1

This is primarily a bugfix release.

• MITKRB5-SA-2010-002 CVE-2010-0628 denial of service in SPNEGO
• Support IPv6 in kpasswd client.
• Fix an authorization data type number assignment that conflicted with an undocumented Microsoft usage.

Major changes in 1.8

The krb5-1.8 release contains a large number of changes, featuring improvements in the following broad areas:

• Code quality
• Developer experience
• Performance
• End-user experience
• Administrator experience
• Protocol evolution

Code quality:

• Move toward test-driven development -- new features have test code, or at least written testing procedures.
• Remove applications to a separate distribution to simplify independent maintenance.
• Increase conformance to coding style
  • "The great reindent"
  • Selective refactoring

Developer experience

• Crypto modularity -- vendors can more easily substitute their own crypto implementations, which might be hardware-accelerated or validated to FIPS 140, for the builtin crypto implementation that has historically shipped as part of MIT Kerberos. Currently, only an OpenSSL provider is included, but others are planned for the future.
• Move toward improved KDB interface
• Improved API for verifying and interrogating authorization data Performance:
• Investigate and remedy repeatedly-reported performance bottlenecks.
• Encryption performance -- new crypto API with opaque key structures, to allow for optimizations such as caching of derived keys

End-user experience:

• Reduce DNS dependence by implementing an interface that allows client library to track whether a KDC supports service principal referrals.

Administrator experience:

• Disable DES by default -- this reduces security exposure from using an increasingly insecure cipher.
• More versatile crypto configuration, to simplify migration away from DES -- new configuration syntax to allow inclusion and exclusion of specific algorithms relative to a default set.
• Account lockout for repeated login failures -- mitigates online password guessing attacks, and helps with some enterprise regulatory compliance.
• Bridge layer to allow Heimdal HDB modules to act as KDB backend modules. This provides a migration path from a Heimdal to an MIT KDC.

Protocol evolution:

• FAST enhancements -- preauthentication framework enhancements to allow a client to securely negotiate the use of FAST with a KDC of unknown capabilities.
• Microsoft Services for User (S4U) compatibility: S4U2Self, also known as "protocol transition", allows for service to ask a KDC for a ticket to themselves on behalf of a client authenticated via a different means; S4U2Proxy allows a service to ask a KDC for a ticket to another service on behalf of a client.
• Anonymous PKINIT -- allows the use of public-key cryptography to anonymously authenticate to a realm
• Support doing constrained delegation similar to Microsoft's S4U2Proxy without the use of the Windows PAC. This functionality uses a protocol compatible with Heimdal.

Known Bugs

Known bugs reported against krb5-1.8.4 are listed here.

Documentation for krb5-1.8.4

Please note that the HTML versions of these documents are converted from texinfo, and that the conversion is imperfect. If you want PostScript or GNU info versions, please download the documentation tarball.

• install guide
• user guide
• admin guide
• krb425 guide
• documentation tarball

Retrieving Kerberos 5 Release 1.8.4

You may retrieve the Kerberos 5 Release 1.8.4 source from here. If you need to acquire the sources from some other distribution site, you may verify them against the detached PGP signature for krb5-1.8.4.