Zimbra Collaboration Suite Cross Site Scripting

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#  
# COMPASS SECURITY ADVISORY https://www.compass-security.com  
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#  
# CVE ID : CVE-2017-8802  
# Product: Zimbra Collaboration Suite (ZCS) [1]  
# Vendor: Synacor Inc. [2]  
# Subject: Stored Cross-Site Scripting (XSS) Vulnerability  
# Risk: High  
# Effect: Exploitable by Anonymous Internet Adversaries  
# Triggered in the Context of an Authenticated Zimbra Email User  
# Authors: Damian Pfammatter ([email protected])  
# Alessandro Zala ([email protected])  
# Date: January 10th 2018  
#  
####################################################################################################  
  
  
Introduction:  
-------------  
The Zimbra Collaboration Suite (ZCS) is a collaborative software suite that includes Email servers  
as well as Email clients. According to the product website, more than 500 million people are  
currently using the Email collaboration tool [1].  
  
Security Analysts of Compass Security Schweiz AG [3] discovered a Stored Cross-Site Scripting (XSS)  
vulnerability in the Zimbra Email web client, potentially resulting in a number of different attack  
scenarios.  
  
  
Affected Versions:  
------------------  
No confirmed information about all affected versions is available. Versions prior to 8.8 GA Release  
are likely affected.  
  
  
Technical Description:  
----------------------  
The Zimbra Email web client is affected by a Stored Cross-Site Scripting (XSS) vulnerability.  
  
Remote attackers can target the vulnerability by sending an Email with XSS payload (e.g. JavaScript)  
in its body. In case the recipient selects the email in the Zimbra client, and accesses the "Show  
Snippet" functionality using the "Q" shortcut, the XSS payload is executed in the context of the  
recipient's Zimbra client.  
  
For example through social engineering, attackers could bring their victims into pressing "Q" while  
reading the compromised email, triggering the payload. Beside others, the malicious payload could  
compromise the confidentility, integrity as well as availability of the victim's emails. Also it  
could be possible to change Zimbra settings of the corresponding victim.  
  
  
Hotfix:  
-------  
The corresponding patch has been released in version 8.8.0 Beta2 [4] (Bug #107925). The patch is  
part of public release 8.8 GA Release.  
  
  
Timeline:  
---------  
2017-05-04: Vulnerability discovered  
2017-05-05: Initial vendor notification  
2017-05-05: Vendor confirmed security issue  
2017-05-05: MITRE reserved CVE-2017-8802 for the issue  
2017-12-12: Vendor released security fix & guidance to its customers  
2018-01-10: Public disclosure  
  
  
References:  
-----------  
[1] https://www.zimbra.com/  
[2] https://www.synacor.com/  
[3] https://www.compass-security.com/research/advisories/  
[4] https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories  
`