NetBSD Security Advisory 2014-007: bozohttpd basic http authentication bypass

[NetBSD Security Officer <security-officer%NetBSD.org@localhost>]

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                 NetBSD Security Advisory 2014-007
                 =================================

Topic:          bozohttpd basic http authentication bypass

Version:        NetBSD-current:         20140708
                NetBSD 6.1*:            affected
                NetBSD 6.0*:            affected
                NetBSD 5.2*:            affected
                NetBSD 5.1*:            affected
                pkgsrc:                 bozohttpd package prior to 20140708.

Severity:       Remote user may access protected files

Fixed:          NetBSD-current:         July 8th, 2014
                NetBSD-6 branch:        July 10th, 2014
                NetBSD-6-1 branch:      July 10th, 2014
                NetBSD-6-0 branch:      July 10th, 2014
                NetBSD-5 branch:        July 10th, 2014
                NetBSD-5-2 branch:      July 10th, 2014
                NetBSD-5-1 branch:      July 10th, 2014
                pkgsrc:         bozohttpd-20140708 corrects this issue

Please note that NetBSD releases prior to 5.1 are no longer supported.
It is recommended that all users upgrade to a supported release.


Abstract
========

When checking for restricted access via .htpasswd files, bozohttpd
fails to properly check for truncation, allowing specially crafted
requests to bypass access control without a password.  Files of
length 10 or more are not affected.


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

A call to snprintf() was not properly checking for truncation of
a provided user path, allowing a later concatenation of the
".htpasswd" file name to exceed the maximum pathname length.  This
stops the check for .htpasswd file from working correctly, bypassing
the basic HTTP authentication scheme.  Files with names longer than
".htpasswd" are not visible as they require at least enough for a
valid path to be available.


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

This problem only affects users of .htpasswd files.  The simplest
fix is to install the latest pkgsrc bozohttpd which fixes this
problem (and use it instead of the system httpd).

Alternatively, to fetch a fitting base.tgz from the releng builds
and install a fixed httpd from there:

cd /var/tmp
ftp 
http://nyftp.netbsd.org/pub/NetBSD-daily/<rel>/<build>/<arch>/binary/sets/base.tgz
cd /
tar xzpf /var/tmp/base.tgz ./usr/libexec/httpd

with the following replacements:
<rel>   = the release version you are using
<build> = the source date of the build. 20140710* and later will fit
<arch>  = your system's architecture

The following instructions describe how to upgrade your bozohttpd
binaries by updating your source tree and rebuilding and
installing a new version of bozohttpd.

The following instructions describe how to upgrade your bozohttpd
binary by updating your source tree and rebuilding and installing
a new version of bozohttpd.

* NetBSD-current:

        Systems running NetBSD-current dated from before 2014-07-08
        should be upgraded to NetBSD-current dated 2014-07-10 or later.

        The following files/directories need to be updated from the
        netbsd-current CVS branch (aka HEAD):
                src/libexec/httpd

        To update from CVS, re-build, and re-install bozohttpd:
                # cd src
                # cvs update -d -P libexec/httpd
                # cd libexec/httpd
                # make USETOOLS=no cleandir dependall
                # make USETOOLS=no install

* NetBSD 6.*:

        Systems running NetBSD 6.* sources dated from before
        2014-07-10 should be upgraded from NetBSD 6.* sources dated
        2014-07-10 or later.

        The following files/directories need to be updated from the
        netbsd-6, netbsd-6-1 or netbsd-6-0 branches:
                src/libexec/httpd

        To update from CVS, re-build, and re-install bozohttpd:

                # cd src
                # cvs update -r <branch_name> -d -P libexec/httpd
                # cd libexec/httpd
                # make USETOOLS=no cleandir dependall
                # make USETOOLS=no install

* NetBSD 5.*:

        Systems running NetBSD 5.* sources dated from before
        2014-07-10 should be upgraded from NetBSD 5.* sources dated
        2014-07-10 or later.

        The following files/directories need to be updated from the
        netbsd-5, netbsd-5-2 or netbsd-5-1 branches:
                src/libexec/httpd

        To update from CVS, re-build, and re-install bozohttpd:

                # cd src
                # cvs update -r <branch_name> -d -P libexec/httpd
                # cd libexec/httpd
                # make USETOOLS=no cleandir dependall
                # make USETOOLS=no install


Thanks To
=========

Thanks go to Mateusz Kocielski who found this problem and supplied
the fixes.


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

        2014-07-17      Initial release


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

Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at 
  http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2014-007.txt.asc

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

Copyright 2014, The NetBSD Foundation, Inc.  All Rights Reserved.
Redistribution permitted only in full, unmodified form.

$NetBSD: NetBSD-SA2014-007.txt,v 1.1 2014/07/17 21:02:39 tonnerre Exp $

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