surgical_havoc_mutate() in custom mutator helpers

This commit is contained in:
Andrea Fioraldi
2020-03-23 10:47:17 +01:00
parent ee9447de01
commit f32d1022bd
4 changed files with 279 additions and 6 deletions

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@ -0,0 +1,2 @@
all:
$(CC) $(CFLAGS) -fPIC -shared -g -I ../../include example.c -o libexamplemutator.so

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@ -7,7 +7,7 @@ Note that if you compile with python3.7 you must use python3 scripts, and if
you use pyton2.7 to compile python2 scripts!
example.c - this is a simple example written in C and should be compiled to a
shared library
shared library. Use make to compile it and produce libexamplemutator.so
example.py - this is the template you can use, the functions are there but they
are empty

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@ -0,0 +1,266 @@
#ifndef CUSTOM_MUTATOR_HELPERS
#define CUSTOM_MUTATOR_HELPERS
#include "config.h"
#include "types.h"
#include <stdlib.h>
#define LIMIT_RAND(limit) (rand() % (limit))
static void surgical_havoc_mutate(u8 *out_buf, s32 begin, s32 end) {
static s8 interesting_8[] = {INTERESTING_8};
static s16 interesting_16[] = {INTERESTING_8, INTERESTING_16};
static s32 interesting_32[] = {INTERESTING_8, INTERESTING_16, INTERESTING_32};
switch (LIMIT_RAND(12)) {
case 0: {
/* Flip a single bit somewhere. Spooky! */
s32 bit_idx = ((LIMIT_RAND(end - begin) + begin) << 3) + LIMIT_RAND(8);
out_buf[bit_idx >> 3] ^= 128 >> (bit_idx & 7);
break;
}
case 1: {
/* Set byte to interesting value. */
u8 val = interesting_8[LIMIT_RAND(sizeof(interesting_8))];
out_buf[(LIMIT_RAND(end - begin) + begin)] = val;
break;
}
case 2: {
/* Set word to interesting value, randomly choosing endian. */
if (end - begin < 2) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 1) break;
switch (LIMIT_RAND(2)) {
case 0:
*(u16 *)(out_buf + byte_idx) =
interesting_16[LIMIT_RAND(sizeof(interesting_16) >> 1)];
break;
case 1:
*(u16 *)(out_buf + byte_idx) =
SWAP16(interesting_16[LIMIT_RAND(sizeof(interesting_16) >> 1)]);
break;
}
break;
}
case 3: {
/* Set dword to interesting value, randomly choosing endian. */
if (end - begin < 4) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 3) break;
switch (LIMIT_RAND(2)) {
case 0:
*(u32 *)(out_buf + byte_idx) =
interesting_32[LIMIT_RAND(sizeof(interesting_32) >> 2)];
break;
case 1:
*(u32 *)(out_buf + byte_idx) =
SWAP32(interesting_32[LIMIT_RAND(sizeof(interesting_32) >> 2)]);
break;
}
break;
}
case 4: {
/* Set qword to interesting value, randomly choosing endian. */
if (end - begin < 8) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 7) break;
switch (LIMIT_RAND(2)) {
case 0:
*(u64 *)(out_buf + byte_idx) =
(s64)interesting_32[LIMIT_RAND(sizeof(interesting_32) >> 2)];
break;
case 1:
*(u64 *)(out_buf + byte_idx) =
SWAP64((s64)interesting_32[LIMIT_RAND(sizeof(interesting_32) >> 2)]);
break;
}
break;
}
case 5: {
/* Randomly subtract from byte. */
out_buf[(LIMIT_RAND(end - begin) + begin)] -= 1 + LIMIT_RAND(ARITH_MAX);
break;
}
case 6: {
/* Randomly add to byte. */
out_buf[(LIMIT_RAND(end - begin) + begin)] += 1 + LIMIT_RAND(ARITH_MAX);
break;
}
case 7: {
/* Randomly subtract from word, random endian. */
if (end - begin < 2) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 1) break;
if (LIMIT_RAND(2)) {
*(u16 *)(out_buf + byte_idx) -= 1 + LIMIT_RAND(ARITH_MAX);
} else {
u16 num = 1 + LIMIT_RAND(ARITH_MAX);
*(u16 *)(out_buf + byte_idx) =
SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) - num);
}
break;
}
case 8: {
/* Randomly add to word, random endian. */
if (end - begin < 2) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 1) break;
if (LIMIT_RAND(2)) {
*(u16 *)(out_buf + byte_idx) += 1 + LIMIT_RAND(ARITH_MAX);
} else {
u16 num = 1 + LIMIT_RAND(ARITH_MAX);
*(u16 *)(out_buf + byte_idx) =
SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) + num);
}
break;
}
case 9: {
/* Randomly subtract from dword, random endian. */
if (end - begin < 4) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 3) break;
if (LIMIT_RAND(2)) {
*(u32 *)(out_buf + byte_idx) -= 1 + LIMIT_RAND(ARITH_MAX);
} else {
u32 num = 1 + LIMIT_RAND(ARITH_MAX);
*(u32 *)(out_buf + byte_idx) =
SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) - num);
}
break;
}
case 10: {
/* Randomly add to dword, random endian. */
if (end - begin < 4) break;
s32 byte_idx = (LIMIT_RAND(end - begin) + begin);
if (byte_idx >= end - 3) break;
if (LIMIT_RAND(2)) {
*(u32 *)(out_buf + byte_idx) += 1 + LIMIT_RAND(ARITH_MAX);
} else {
u32 num = 1 + LIMIT_RAND(ARITH_MAX);
*(u32 *)(out_buf + byte_idx) =
SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) + num);
}
break;
}
case 11: {
/* Just set a random byte to a random value. Because,
why not. We use XOR with 1-255 to eliminate the
possibility of a no-op. */
out_buf[(LIMIT_RAND(end - begin) + begin)] ^= 1 + LIMIT_RAND(255);
break;
}
}
}
#endif

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@ -5,6 +5,9 @@
Shengtuo Hu <h1994st@gmail.com>
*/
// You need to use -I /path/to/AFLplusplus/include
#include "custom_mutator_helpers.h"
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
@ -21,7 +24,7 @@ static size_t data_size = 100;
void afl_custom_init(unsigned int seed) {
srand(seed);
srand(seed); // needed also by surgical_havoc_mutate()
}
@ -54,9 +57,11 @@ size_t afl_custom_fuzz(uint8_t **buf, size_t buf_size, uint8_t *add_buf,
memcpy(mutated_out, commands[rand() % 3], 3);
// Mutate the payload of the packet
for (int i = 3; i < mutated_size; i++) {
int i;
for (i = 0; i < 8; ++i) {
mutated_out[i] = (mutated_out[i] + rand() % 10) & 0xff;
// Randomly perform one of the (no len modification) havoc mutations
surgical_havoc_mutate(mutated_out, 3, mutated_size);
}