ftpd setproctitle vulnerability

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===========================================================================
              AUSCERT External Security Bulletin Redistribution

              ESB-2000.170 -- NetBSD Security Advisory 2000-009
                       ftpd setproctitle vulnerability
                                14 July 2000

===========================================================================

	AusCERT Security Bulletin Summary
	---------------------------------

Product:		ftpd
Vendor:			NetBSD
Operating System:	NetBSD

Platform:		N/A

Impact:			Execute Arbitrary Code/Commands
			
Access Required:	Remote

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                 NetBSD Security Advisory 2000-009
                 =================================

Topic:		ftpd setproctitle vulnerability.
Version:	All releases before 2000/07/08
Severity:	High: Potential remote root access.


Abstract
========

An improper use of the setproctitle() library function by ftpd may
allow a malicious remote ftp client to subvert an FTP server,
including possibly getting remote access to a system.


Technical Details
=================

The BSD setproctitle() function, like printf(), accepts a format
string and a variable number of arguments; the format string is
interpreted to determine how to display the other arguments to the
function.  

If the format string can contain arbitrary user-supplied data, it may
be possible to trick the program into reading or writing arbitrary
memory locations, resulting in a security compromise.

A more extensive audit of the NetBSD sources for problems of this form
is under way.


Solutions and Workarounds
=========================

This problem affects all versions of NetBSD.  Patches are available
for the NetBSD-1.4 series of releases.

If you're runing NetBSD 1.4, 1.4.1, or 1.4.2, fetch the following
patch, apply it to src/libexec/ftpd/ftpd.c using the patch(1) command,
rebuild and reinstall ftpd, and kill off any existing FTP daemons (to
ensure that any improperly granted access is revoked).

    ftp://ftp.NetBSD.ORG/pub/NetBSD/misc/security/patches/20000708-ftpd

If you're running a version of NetBSD-current or the NetBSD 1.5 branch
from before 2000/07/05, you should update to a newer version of
NetBSD-current.  Similarly, if you're running a version of
NetBSD-release (NetBSD 1.4 branch) from before 2000/07/08, you should
update to a newer version of NetBSD-release.

Thanks To
=========

Jun-ichiro Hagino <itojun@netbsd.org>


Revision History
================

	20000708	Initial version.


More Information
================

Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.ORG/ and http://www.NetBSD.ORG/Security/.


Copyright 2000, The NetBSD Foundation, Inc.  All Rights Reserved.

$NetBSD: NetBSD-SA2000-009.txt,v 1.1 2000/07/08 21:03:11 sommerfeld Exp $

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