== Subject:     DCE-RPC fragment length field is incorrectly checked.
== CVE ID#:     CVE-2013-4408
== Versions:    All versions of Samba later than 3.4.0
== Summary:     Incorrect length checks on DCE-RPC fragment lengths
==              cause Samba client utilities including winbindd to
==              be vulnerable to buffer overrun exploits.


Samba versions 3.4.0 and above (versions 3.4.0 - 3.4.17, 3.5.0 -
3.5.22, 3.6.0 - 3.6.21, 4.0.0 - 4.0.12 and including 4.1.2) are
vulnerable to buffer overrun exploits in the client processing of
DCE-RPC packets. This is due to incorrect checking of the DCE-RPC
fragment length in the client code.

This is a critical vulnerability as the DCE-RPC client code is part of
the winbindd authentication and identity mapping daemon, which is
commonly configured as part of many server installations (when joined
to an Active Directory Domain). A malicious Active Directory Domain
Controller or man-in-the-middle attacker impersonating an Active
Directory Domain Controller could achieve root-level access by
compromising the winbindd process.

Samba server versions 3.4.0 - 3.4.17 and versions 3.5.0 - 3.5.22 are
also vulnerable to a denial of service attack (server crash) due to a
similar error in the server code of those versions.

Samba server versions 3.6.0 and above (including all 3.6.x versions,
all 4.0.x versions and 4.1.x) are not vulnerable to this problem.

In addition range checks were missing on arguments returned from calls
to the DCE-RPC functions LookupSids (lsa and samr), LookupNames (lsa and samr)
and LookupRids (samr) which could also cause similar problems.

As this was found during an internal audit of the Samba code there are
no currently known exploits for this problem (as of December 9th 2013).

Patch Availability

Patches addressing all these issues have been posted to:

Samba versions 3.6.22, 4.0.13, and 4.1.3 have been released to
address this issue. Patches for 3.4.17 and 3.5.22 are available at the above URL.




This problem was found by an internal audit of the Samba code by
Stefan Metzmacher and Michael Adam of SerNet.

Patches provided by Stefan Metzmacher and Jeremy Allison of the Samba

== Our Code, Our Bugs, Our Responsibility.
== The Samba Team