Parallels Plesk 7.0 - 8.2 | Open URL Redirection Vulnerability

Parallels Plesk 7.0 - 8.2 | Open URL Redirection Vulnerability

1. OVERVIEW

The Plesk versions from 7.0 to 8.2 are vulnerable to Open URL
Redirection when "Enable [email protected]" access format, a new
feature introduced in Plesk 7.0, is enabled in user preferences.

2. BACKGROUND

Parallels Plesk Panel is a turnkey Web hosting system that includes
fully automated billing and provisioning, an integrated SiteBuilder,
and access to over a hundred Web-based applications that you can use
to create unique service plans that meet a variety of customer needs.

3. VULNERABILITY DESCRIPTION

The Plesk 7.0 - 8.2 versions contain a flaw that allows a remote cross
site redirection attack. This flaw exists because the application does
not properly parse Query String parameter to set it apart from
[email protected] format upon submission to the default web root url
(/) of the affected domain (i.e www.domain.com/) . To further explain,
when the URL with the format, http://domain.com/[email protected], is
requested, the Plesk mistakenly parses domain.com/? as a web user and
attacker.com as the main domain. This allows an attacker to create a
specially crafted URL, that if clicked, would redirect a victim from
the intended legitimate web site (domain.com) to an arbitrary web site
(attacker.in) of the attacker's choice. This flaw takes place in the
file, at_domains_index.html, part of the Plesk application.
Vulnerable code snippets of at_domains_index.html are as follows:

////////////////////////////////////////////////////////////////////////////////////
…
<title>Relocate</title>
<script language="javascript">
var url = window.location.href;
if (url.charAt(url.length - 1) != "/")
url = url + "/";
var s = url.indexOf("//") + 2;
var e = url.indexOf("@");
if (e > 0) {
var atpart = url.substring(s, e);
var newurl = url.substring(0, s) + url.substring(e + 1 , url.length);
window.location = newurl + "~" + atpart + "/";
} else {
window.location= "/index.html";
}
</script>
…
////////////////////////////////////////////////////////////////////////////////////

Domains with [email protected] access format disabled are not vulnerable.

4. VERSIONS AFFECTED

7.0 - 8.2

5. PROOF-OF-CONCEPT/EXPLOIT

http://www.victim.com/?@&#37;61&#37;74&#37;74&#37;61&#37;63&#37;6b&#37;65&#37;72&#37;2e&#37;69&#37;6e
http://www.victim.com/[email protected]

6. SOLUTION

Vendor will not release patch file for customers of affected versions.

One of the following:

• Use Plesk 8.3 or higher
• Disable [email protected] access format
• Patch at_domains_index.html with
  http://yehg.net/lab/pr0js/advisories/plesk/patches/open-redirect/at_domains_index.html.zip
  [note: extract & edit file to modify your index url]

7. VENDOR

Parallels Holdings Ltd
http://www.parallels.com/

8. CREDIT

Aung Khant, http://yehg.net, YGN Ethical Hacker Group, Myanmar.

9. DISCLOSURE TIME-LINE

2011-03-09: notified vendor though publicly available emails
2011-03-22: no reply
2011-03-23: reported again through an email that asked feedback for
using trial version of Plesk 10.x
2011-03-23: vendor confirmed that the issue is affected till the version 8.2
2011-03-25: vulnerability disclosed

10. REFERENCES

Original Advisory URL:
http://yehg.net/lab/pr0js/advisories/[plesk_7.0-8.2]_open_url_redirection
Parallels Plesk Home Page: http://www.parallels.com/products/plesk
OWASP Top 10 2010 - A 10:
http://www.owasp.org/index.php/Top_10_2010-A10-Unvalidated_Redirects_and_Forwards
SANS Top 25 - Rank 23: http://cwe.mitre.org/top25/#CWE-601
CWE-601: http://cwe.mitre.org/data/definitions/601.html

#yehg [2011-03-25]

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Best regards,
YGN Ethical Hacker Group
Yangon, Myanmar
http://yehg.net
Our Lab | http://yehg.net/lab
Our Directory | http://yehg.net/hwd