|XDR Integer Overflow
Author : Marc Maiffret - firstname.lastname@example.org
XDR Integer Overflow
March 19, 2003
High (Remote Code Execution/Denial of Service)
Sun Microsystems Network Services Library (libnsl)
BSD-derived libraries with XDR/RPC routines (libc)
GNU C library with sunrpc (glibc)
XDR is a standard for the description and encoding of data which is used
heavily in RPC implementations. Several libraries exist that allow a
developer to incorporate XDR into his or her applications. Vulnerabilities
were discovered in these libraries during the testing of new Retina auditing
technologies developed by the eEye research department.
ADAM and EVE are two technologies developed by eEye to remotely and locally
audit applications for the existence of common vulnerabilities. During
ADAM audit, an integer overflow was discovered in the SUN Microsystems
library. By supplying specific integer values in length fields during
transaction, we were able to produce various overflow conditions in UNIX
The xdrmem_getbytes() function in the XDR library provided by Sun
Microsystems contains an integer overflow. Depending on the location and
of the vulnerable xdrmem_getbytes() routine, various conditions may be
presented that can permit an attacker to remotely exploit a service using
this vulnerable routine.
For the purpose of signature development and further security research
sample session is included below that replicates an integer overflow in
rpcbind shipped with various versions of the Solaris operating system.
char evil_rpc =
"\xFF\xFF\xFF\xFF" // RPC argument length
Sun Microsystems was contacted on November 13, 2002 and CERT was contacted
shortly afterwards. Vendors believed to be vulnerable were contacted by
during a grace period of several months. Due to some difficulties
communicating with vendors, after rescheduling several times a release
was set for March 18, 2003.
eEye recommends obtaining the necessary patches or updates from vendors
they become available after the release of this and the CERT advisory.
For a list of vendors and their responses, please review the CERT advisory
You can find the latest copy of this advisory, along with other eEye
research at http://www.eeye.com/.
Riley Hassell - Senior Research Associate
Liver destroyers of the world:
Barnes (DOW!), FX, and last but definitely not least, Heather and Jenn.
Copyright (c) 1998-2003 eEye Digital Security
Permission is hereby granted for the redistribution of this alert
electronically. It is not to be edited in any way without express consent
eEye. If you wish to reprint the whole or any part of this alert in any
other medium excluding electronic medium, please e-mail alert@eEye.com
The information within this paper may change without notice. Use of this
information constitutes acceptance for use in an AS IS condition. There
NO warranties with regard to this information. In no event shall the author
be liable for any damages whatsoever arising out of or in connection with
the use or spread of this information. Any use of this information is
user's own risk.
Please send suggestions, updates, and comments to:
eEye Digital Security