[waraxe-2012-SA#096] - Multiple Vulnerabilities in Zenphoto 1.4.3.3
===============================================================================
Author: Janek Vind "waraxe"
Date: 03. November 2012
Location: Estonia, Tartu
Web: http://www.waraxe.us/advisory-96.html
Description of vulnerable software:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Zenphoto is a standalone CMS for multimedia focused websites. Our focus lies on
being easy to use and having all the features there when you need them (but out
of the way if you do not.)
Zenphoto features support for images, video and audio formats, and the Zenpage
CMS plugin provides a fully integrated news section (blog) and custom pages to
run entire websites.
http://www.zenphoto.org/
https://code.google.com/p/zenphoto/
Affected versions: Zenphoto 1.4.3.3 and older
Patched version: Zenphoto 1.4.3.4
###############################################################################
1. SQL Injection in "zp-core/zp-extensions/failed_access_blocker.php"
###############################################################################
Reason: insufficient sanitization of user-supplied data
Attack vector: user-supplied HTTP header "X_FORWARDED_FOR"
Preconditions:
1. plugin "failed_access_blocker" activated (disabled by default)
"failed_access_blocker" plugin will log every failed authentication attempt:
Php script "zp-core/zp-extensions/failed_access_blocker.php" line 75:
------------------------[ source code start ]----------------------------------
function failed_access_blocker_adminGate($allow, $page) {
...
// add this attempt
$sql = 'INSERT INTO '.prefix('plugin_storage').' (`type`, `aux`,`data`) VALUES
("failed_access", "'.time().'","'.getUserIP().'")';
query($sql);
// check how many times this has happened recently
count = db_count('plugin_storage','WHERE `type`="failed_access" AND
`data`="'.getUserIP().'"');
------------------------[ source code end ]------------------------------------
IP address of the user comes from function "getUserIP()" and is used in SQL
query. Let's look at the function "getUserIP()".
Php script "zp-core/functions.php" line 1979:
------------------------[ source code start ]----------------------------------
function getUserIP() {
if (isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
return sanitize($_SERVER['HTTP_X_FORWARDED_FOR'], 0);
} else {
return sanitize($_SERVER['REMOTE_ADDR'], 0);
------------------------[ source code end ]------------------------------------
Function "sanitize()" does following things to the input data:
1. strips slashes if magic_quotes_gpc=on
2. strips null bytes
3. strips html tags
So we can see, that function "sanitize()" will prevent null byte tricks and
most of the XSS exploits, but it does not escape or delete single and double
quotes, therefore SQL Injection may still be possible. Actually this function
makes SQL Injection more likely to occur because it reverts effects of the
"magic_quotes_gpc". As result of such insuffient input data sanitization,
attacker can use HTTP header "X_FORWARDED_FOR" for SQL Injection.
Test:
Let's use Firefox browser with Tamper Data Add-on.
1. Open admin page:
http://localhost/zenphoto1433/zp-core/admin.php
2. Activate Tamper data (Start Tamper)
3. Try to log in with bogus credentials, Tamper Data triggers
4. "Tamper with request?" -> "Tamper"
5. "Add element" -> X_FORWARDED_FOR=war"axe
6. Click "OK" and tampered request will go to the server
As result we will see blank page (OK 200 response code, content length 0).
But let's look at "debug.log" in "zp-data":
Backtrace: USER ERROR: MySql Error: ( INSERT INTO `[prefix]plugin_storage`
(`type`, `aux`,`data`) VALUES ("failed_access", "1349792737","war"axe") )
failed. MySql returned the error You have an error in your SQL syntax;
check the manual that corresponds to your MySQL server version for the right
syntax to use near 'axe")'
###############################################################################
2. SQL Injection in "zp-core/zp-extensions/search_statistics.php"
###############################################################################
Reason: insufficient sanitization of user-supplied data
Attack vector: user-supplied HTTP header "X_FORWARDED_FOR"
Preconditions:
1. plugin "search_statistics" activated (disabled by default)
Php script "zp-core/zp-extensions/search_statistics.php" line 101:
------------------------[ source code start ]----------------------------------
static function handler($search_statistics, $type, $success, $dynamic,
$iteration) {
...
$sql = 'INSERT INTO '.prefix('plugin_storage').' (`type`, `aux`,`data`) VALUES
("search_statistics", "'.getUserIP().'",'.db_quote(serialize($store)).')';
query($sql);
------------------------[ source code end ]------------------------------------
User's IP address comes from function "getUserIP()" and is used in SQL query.
As shown in previous case, it is possible to use HTTP header "X_FORWARDED_FOR"
for SQL Injection, because "getUserIP()" does not sufficiently sanitize
user-supplied input data.
###############################################################################
3. IP address spoofing vulnerability via HTTP header "X_FORWARDED_FOR"
###############################################################################
Reason: trusting spoofable input data
Attack vector: user-supplied HTTP header "X_FORWARDED_FOR"
Preconditions: none
We saw in two previous cases, that function "getUserIP()" can't be trusted,
because attacker can easily spoof his/her IP addresss by using HTTP header
"X_FORWARDED_FOR". Vulnerable function "getUserIP()" is heavily used in logging
functionality.
Example code lines from "zp-core/zp-extensions/security-logger.php":
security_logger::Logger($success, $user, $name, getUserIP(), 'Back-end',
$auth, $pass);
security_logger::Logger($success, $user, $name, getUserIP(), 'Front-end',
$athority, $pass);
security_logger::Logger(false, $user, $name, getUserIP(), 'Blocked access',
'', $page);
security_logger::Logger(false, $user, $name, getUserIP(), 'Blocked album',
'', $page);
security_logger::Logger(true, $user, $name, getUserIP(), 'user_'.$class,
'zp_admin_auth', $userobj->getUser());
security_logger::Logger(false, $user, $name, getUserIP(), 'XSRF access blocked',
'', $token);
security_logger::Logger($allow, $user, $name, getUserIP(), $action,
'zp_admin_auth', basename($log));
security_logger::Logger($success, $user, $name, getUserIP(), 'setup_'.$action,
'zp_admin_auth', $txt);
So we can conclude, that it is possible for attacker to spoof IP address in
Zenphoto security logs. By injecting newlines ("\n") and tabs ("\t") it's even
possible to add arbitrary fake entries to the security logs.
###############################################################################
4. File Type Restriction Bypass Vulnerability in
"zp-core/zp-extensions/uploader_jQuery/uploader.php"
###############################################################################
Preconditions:
1. Logged in as admin with image upload privileges
2. "uploader_jQuery" plugin activated (active by default)
Php script "zp-core/zp-extensions/uploader_jQuery/uploader.php" line 227:
------------------------[ source code start ]----------------------------------
private function handle_file_upload($uploaded_file, $name, $size, $type,
$error) {
...
$error = $this->has_error($uploaded_file, $file, $error);
if (!$error && $file->name) {
...
move_uploaded_file($uploaded_file, $file_path);
if (is_valid_image($name) || is_valid_other_type($name)) {
...
} else {
$error = UPLOAD_ERR_EXTENSION; // invalid file uploaded
break;
------------------------[ source code end ]------------------------------------
As seen above, uploaded file is first validated by function "has_error":
Php script "zp-core/zp-extensions/uploader_jQuery/uploader.php" line 26:
------------------------[ source code start ]----------------------------------
$types = array_keys($_zp_extra_filetypes);
$types = array_merge($_zp_supported_images, $types);
$types = zp_apply_filter('upload_filetypes',$types);
...
$options = array(
...
'accept_file_types' => '/('.implode('|',$types).')$/i'
...
private function has_error($uploaded_file, $file, $error) {
...
if (!preg_match($this->options['accept_file_types'], $file->name)) {
return 'acceptFileTypes';
------------------------[ source code end ]------------------------------------
We can see, that "preg_match()" regex validation is used for file extension
sanitization. Example validation regex from default installation:
"/(gif|jpg|jpeg|png|bmp|flv|fla|3gp|mov|mp3|mp4|m4v|m4a)$/i"
At first look it seems to be secure - only picture and video files are allowed
to be uploaded. But if we analyze this regex little bit more, then we can spot
one fatal flaw - it does not check for dot character before file extension.
As result, it is possible to upload file named like "info.php.123png" and it
will pass through first validation, done by "has_error()". We can see, that
after "has_error()" uploaded file is moved from temporal location to the target
album directory by "move_uploaded_file()" function. After that second
validation by function "is_valid_image()" follows:
Php script "zp-core/functions-basic.php" line 1173:
------------------------[ source code start ]----------------------------------
function is_valid_image($filename) {
global $_zp_supported_images;
$ext = strtolower(substr(strrchr($filename, "."), 1));
return in_array($ext, $_zp_supported_images);
}
------------------------[ source code end ]------------------------------------
We can see, that file extension is checked again and this time it is secure
validation and can't be fooled. This situation usually means, that exploitation
is not possible, but not this time. Uploaded file is already moved to the target
folder, directly accessible over HTTP and there is missing important piece of
php code, which should delete such files. What code does after failed
"is_valid_image()", is setting up error flag "UPLOAD_ERR_EXTENSION" followed by
"break". This seems to be as syntax error from programmer and will lead to php
fatal error: "Cannot break/continue 1 level". In my local testserver this means
error 500 response from webserver, but still, file is uploaded to the target
directory already and stays there, so exploitation is possible.
Test:
1. Log in as admin with image upload privileges and navigate to upload page:
http://localhost/zenphoto1433/zp-core/admin-upload.php?page=upload&tab=albums
Make sure, that "Upload handler" is "jQuery". In this test target album is
"testalbum".
2. Try to upload php file containing "" and named as
"info.php.123png"
As result we can see error message:
"info.php.123png 0.02 KB Error: Internal Server Error"
Still, despite of the error message, upload succeeded. Uploaded file can
be accessed directly, resulting in php code execution:
http://localhost/zenphoto1433/albums/testalbum/info.php.123png
###############################################################################
5. File Type Restriction Bypass Vulnerability in
"zp-core/admin-functions.php"
###############################################################################
Preconditions:
1. Logged in as admin with image upload privileges
2. "zip_open()" function not available
Php script "zp-core/admin-functions.php" line 2565:
------------------------[ source code start ]----------------------------------
/**
* Unzips an image archive
*
* @param file $file the archive
* @param string $dir where the images go
*/
function unzip($file, $dir) { //check if zziplib is installed
if(function_exists('zip_open')) {
$zip = zip_open($file);
if ($zip) {
while ($zip_entry = zip_read($zip)) { // Skip non-images in the zip file.
$fname = zip_entry_name($zip_entry);
$seoname = internalToFilesystem(seoFriendly($fname));
if (is_valid_image($seoname) || is_valid_other_type($seoname)) {
if (zip_entry_open($zip, $zip_entry, "r")) {
$buf = zip_entry_read($zip_entry, zip_entry_filesize($zip_entry));
...
} else {
require_once(dirname(__FILE__).'/lib-pclzip.php');
$zip = new PclZip($file);
if ($zip->extract(PCLZIP_OPT_PATH, $dir, PCLZIP_OPT_REMOVE_ALL_PATH) == 0) {
------------------------[ source code end ]------------------------------------
We can see that when "zip_open()" function is available, then Zenphoto will read
zip entries from archieve one by one and there is as checking for file type.
Only files with whitelisted extensions are extracted to the target folder.
But in case of missing function "zip_open()" (specific lib not installed)
custom third-party library "PclZip" will be used, this time without any checks
for file extensions. So it is possible to upload zip archive with php files
inside and they will be extracted to the target album, allowing attacker to
gain php level access.
###############################################################################
6. File Existence Disclosure in
"zp-core/zp-extensions/uploader_flash/check.php"
###############################################################################
Preconditions: none
Php script "zp-core/zp-extensions/uploader_flash/check.php" line 26:
------------------------[ source code start ]----------------------------------
$fileArray = array();
foreach ($_POST as $key => $value) {
if ($key != 'folder') {
if (file_exists($_SERVER['DOCUMENT_ROOT'] . $_POST['folder'] . '/' . $value)) {
$fileArray[$key] = $value;
}
}
}
echo json_encode($fileArray);
------------------------[ source code end ]------------------------------------
Test:
-------------------------[ test code start ]-----------------------------------
--------------------------[ test code end ]------------------------------------
Result:
{"test":"..\/..\/..\/..\/..\/..\/..\/..\/etc\/passwd"}
Attacker is able to detect file presence on remote server, because server
response is different in case of existing and non-existent files.
###############################################################################
7. Database Backup Files Unauthorized Access Vulnerability
###############################################################################
Zenphoto offers database backup functionality in admin interface:
Php script "zp-core/utilities/backup_restore.php" line 140:
------------------------[ source code start ]----------------------------------
if (isset($_REQUEST['backup']) && db_connect()) {
...
$folder = SERVERPATH . "/" . BACKUPFOLDER;
$filename = $folder . '/backup-' . date('Y_m_d-H_i_s').'.zdb';
if (!is_dir($folder)) {
mkdir ($folder, FOLDER_MOD);
}
@chmod($folder, FOLDER_MOD);
$handle = fopen($filename, 'w');
------------------------[ source code end ]------------------------------------
We can see that database backup files are named using simple naming scheme.
Created backup files are directly accessible without any restrictions:
http://localhost/zenphoto1433/backup/backup-2012_10_07-19_20_15.zdb
As result there may be leakage of sensitive information, like admin's hashed
credentials:
s:4:"user";s:6:"waraxe";s:4:"pass";s:40:"123456789abcdef123456789abc...
There is "IndexIgnore *" directive in ".htaccess" file, so by default
directory browsing is not possible and filename must be guessed somehow,
but still there are vulnerable zenphoto installations on Internet:
Google Dork:
filetype:zdb inurl:backup
Besides, there is about 60 * 60 * 24 * 365 = 31 536 000 possible filenames
per year, so it is possible to use bruteforce method and try to guess backup's
filename.
###############################################################################
8. Reflected XSS in "zp-core/zp-extensions/federated_logon/OpenID_logon.php"
###############################################################################
Reason:
1. uninitialized variables "$msg", "$error", "$success"
2. insufficient sanitization of html output
Attack vector:
1. user-supplied parameters "msg", "error", "success"
2. user-supplied GET parameter "redirect"
Preconditions:
1. register_globals=on (for parameters "msg", "error", "success")
Php script "zp-core/zp-extensions/federated_logon/OpenID_logon.php" line 38:
------------------------[ source code start ]----------------------------------
$msg"; } ?>
$error"; } ?>
$success"; } ?>
------------------------[ source code end ]------------------------------------
Tests:
http://localhost/zenphoto1433/zp-core/zp-extensions/federated_logon/OpenID_logon.php?msg=
http://localhost/zenphoto1433/zp-core/zp-extensions/federated_logon/OpenID_logon.php?error=
http://localhost/zenphoto1433/zp-core/zp-extensions/federated_logon/OpenID_logon.php?success=
http://localhost/zenphoto1433/zp-core/zp-extensions/federated_logon/OpenID_logon.php?redirect="+onclick=alert(123)+w="
###############################################################################
9. Reflected XSS in "zp-core/zp-extensions/federated_logon/Verisign_logon.php"
###############################################################################
Reason: insufficient sanitization of html output
Attack vector: user-supplied GET parameter "redirect"
Preconditions: none
Test:
http://localhost/zenphoto1433/zp-core/zp-extensions/federated_logon/Verisign_logon.php?redirect="+onclick=alert(123)+w="
###############################################################################
10. Reflected XSS in "themes/stopdesign/comment_form/comment_form.php"
###############################################################################
Reason:
1. uninitialized variable "$_zp_themeroot"
2. insufficient sanitization of html output
Attack vector: user-supplied parameter "_zp_themeroot"
Preconditions: register_globals=on
Php script "themes/stopdesign/comment_form/comment_form.php" line 5:
------------------------[ source code start ]----------------------------------
global $_zp_themeroot;
?>