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@stake, Inc.
www.atstake.com
Security Advisory
Advisory Name: Remote Vulnerabilities in Bugzilla
Release Date: 04/30/2001
Application: Bugzilla (2.10)
Platform: Unix or any other platform supporting perl CGI scripts and
MySQL (most often Unix+Apache)
Severity: Remote users could execute arbitrary commands as the web
server user, view unauthorized information.
Authors: Dave Aitel [daitelat_private],
Andrew Danforth [acdat_private]
Vendor Status: Vendor has fixed version
CVE Candidate: CAN-2001-0329, CAN-2001-0330
Reference: www.atstake.com/research/advisories/2001/a043001-1.txt
Executive Summary:
Bugzilla is a web-based bug (and enhancement) tracking engine built over
MySQL. It's often used for distributed OpenSource development, but is used
by corporations (both internally and externally) as well. A bug in
Bugzilla allows remote users who have registered with shell characters in
their email addresses to execute commands on the web server as an
unprivileged user.
Overview:
The attack is to register as a user named "|somecommand;@yourdomain.com"
(root access at yourdomain.com _may_ be required.) Then submit a bug.
It is prudent to segment Bugzilla (or otherwise interactive
web sites) from code repository and download sites. This would prevent
this, or future bugs from compromising the source tree or distribution
binaries of an OpenSource or collaborative project.
Detailed Description:
Perl's system call acts differently based on the type of argument given;
if it's a list, it takes the first element as the program and the rest as
the arguments. If the argument is a scalar, it feeds it thru sh for
parsing. The Bugzilla guys got it right for one of the system() calls
(see below), but the rest are broken.
- - --- output from some grepping (greppage, greps?) ---
Broken (scalars):
post_bug.cgi:system("./processmail $id $::COOKIE{'Bugzilla_login'}");
process_bug.cgi: system("./processmail $num $::FORM{'who'}");
process_bug.cgi: system("./processmail $k $::FORM{'who'}");
Not Broken (list):
process_bug.cgi: system("./processmail", "-forcecc", $origCcString,
$id, $::FORM{'who'});
A similar vulnerability is described at
http://packetstorm.securify.com/0005-exploits/bugzilla.txt
Additionally, it is possible to obtain the Bugzilla global configuration
code by pointing a web browser at http://bug.zilla.site/globals.pl. The
conf file contains some site-specific configuration directives such as
paths and global variables, the juiciest of which are the database
username and password.
This brings up an typical problem with perly web apps. Programmers often
define globals and configuration info in modules or files containing bits
of perl code, and 'use' or 'require' them in their cgi. Typically, the
perl scripts are named foo.cgi so the web server configuration doesn't
need to be modified (ala AddHandler cgi-script .pl). The modules and such
retain .pl or .pm extensions, so the web server feeds them to a requestor
as plain text.
Solutions:
If you can you should upgrade to the latest version of Bugzilla 2.12 which
fixes these problems.
As a temporary solution, all Bugzilla system() calls should be modified to
pass arguments as an array rather than a scalar.
Also, on line 469 of defparams.pl, replace the regular expression
definition
q:^[^@, ]*@[^@, ]*\\.[^@, ]*$:
with
q:^[\w-\./]+@[A-Za-z\d-\.]+$:
Please note that the new regular expression will not match all valid RFC
822 email addresses. A perl regex that does just that can be found at
<http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/ckaddr.gz>, but
Integrating it with Bugzilla is beyond the scope of this advisory.
Scripts:
This is a script that should fix the system call bugs - run it in the
bugzilla directory:
<cut here>
#!/usr/bin/perl
#
# bugzilla system() fixer -- run in bugzilla CGI directory
#
# Andrew Danforth <acdat_private>, 2001
# note, grep and ed must be in path. Tested on Debian Linux.
foreach(`grep -n system\\( *.cgi`) {
my ($file, $line, $code) = split(/:/, $_, 3);
next if ($code =~ /,/);
if ($code !~ /system\(("[^"]+")\)/) {
print "couldn't find arguments to system for $file:$line\n";
next;
}
print "changing line $line for $file\n";
open ED, "|ed -s $file";
print ED $line, "c\n", $`, "system(", join('","', split(' ', $1)), ")",
$', ".\nw\nq\n";
close ED;
}
<end cut>
Vendor Response:
Vendor has released a new release, Bugzilla 2.12, that addresses these
problems:
http://ftp.mozilla.org/pub/webtools/bugzilla-2.12.tar.gz
Common Vulnerabilities and Exposures (CVE) Information:
The Common Vulnerabilities and Exposures (CVE) project has assigned
the following names to these issues. These are candidates for
inclusion in the CVE list (http://cve.mitre.org), which standardizes
names for security problems.
CAN-2001-0329 - shell metacharacters in email addresses
CAN-2001-0330 - sensitive information from globals.pl
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