PHP Input Validation Flaw in ZipArchive::extractTo() May Let Remote Users Overwrite Files on the Target System
SecurityTracker Alert ID: 1021303|
SecurityTracker URL: http://securitytracker.com/id/1021303
(Links to External Site)
Updated: Dec 23 2008|
Original Entry Date: Dec 4 2008
Execution of arbitrary code via network, Modification of user information, User access via network|
Fix Available: Yes Vendor Confirmed: Yes Exploit Included: Yes |
Version(s): 5.2.6 and prior versions|
A vulnerability was reported in PHP. A remote user may be able to create or overwrite files on the target system.|
The ZipArchive::extractTo() function does not properly validate user-supplied input. A remote user can supply a zip archive containing a specially crafted file name to PHP applications that use the function to cause the target application to create or overwrite files on target system with the privileges of the web service.
A remote user may be able to exploit this to execute arbitrary code on the target system with the privileges of the web service.
A demonstration exploit file name is provided:
The vendor was notified on June 23, 2008.
Stefan Esser of SektionEins GmbH reported this vulnerability.
The original advisory is available at:
A remote user can create or overwrite files on the target system with the privileges of the web service.|
The vendor has issued a fixed version (5.2.7), available at:|
Vendor URL: www.php.net/ (Links to External Site)
Input validation error|
|Underlying OS: Linux (Any), UNIX (Any), Windows (Any)|
This archive entry has one or more follow-up message(s) listed below.|
Source Message Contents
Subject: [Full-disclosure] Advisory 06/2008: PHP ZipArchive::extractTo()|
-----BEGIN PGP SIGNED MESSAGE-----
-= Security Advisory =-
Advisory: PHP ZipArchive::extractTo() Directory Traversal Vulnerability
Release Date: 2008/12/04
Last Modified: 2008/12/04
Author: Stefan Esser [stefan.esser[at]sektioneins.de]
Application: PHP 5 <= 5.2.6
Severity: PHP applications using ZipArchive::extractTo() to unpack zip
archive files can be tricked to overwrite arbitrary files
writable by the webserver which might result in PHP remote
Vendor Status: Vendor has released PHP 5.2.7 which contains an updated
ZipArchive::extractTo() method that flattens the filename
stored inside zip archives before unpacking
Quote from http://www.php.net
"PHP is a widely-used general-purpose scripting language that
is especially suited for Web development and can be embedded
PHP comes with the zip extension that provides the ZipArchive
class for zip archive manipulation. During an audit of a large
scale PHP applications that uses ZipArchive::extractTo() to
unpack user uploaded zip archives to temporary directories it
was discovered that ZipArchive::extractTo() does not flatten
the filenames stored inside the zip archives.
Therefore it is possible to create zip archives containing
relative filenames that when unpacked will create or overwrite
files outside of the temporary directory.
In the applications like the one in question this results in
a remote PHP code execution vulnerability, because we are
able to drop new PHP files in writable directories within
the webserver's document root directory.
No details required. To exploit this an attacker just needs to
create a zip archive containing filenames like
An easy way to achieve that is to just store a file with a long
name inside the zip archive and then change it with a hex editor
Proof of Concept:
SektionEins GmbH is not going to release a proof of concept
exploit for this vulnerability.
23. June 2008 - Notified firstname.lastname@example.org
04. December 2008 - PHP developers released PHP 5.2.7
04. December 2008 - Public Disclosure
It is recommended to upgrade to the latest version of PHP
which also fixes additional vulnerabilities reported by
Grab your copy at:
The Common Vulnerabilities and Exposures project (cve.mitre.org) has
not assigned a name to this vulnerability yet.
pub 1024D/15ABDA78 2004-10-17 Stefan Esser <email@example.com>
Key fingerprint = 7806 58C8 CFA8 CE4A 1C2C 57DD 4AE1 795E 15AB DA78
Copyright 2008 SektionEins GmbH. All rights reserved.
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