Merge pull request #1841 from AFLplusplus/dev

Dev

3 files changed, 683 insertions, 1 deletions

diff --git a/custom_mutators/aflpp_tritondse/aflpp_tritondse.py b/custom_mutators/aflpp_tritondse/aflpp_tritondse.py
index 58b506b6..58739696 100644
--- a/custom_mutators/aflpp_tritondse/aflpp_tritondse.py
+++ b/custom_mutators/aflpp_tritondse/aflpp_tritondse.py
@@ -164,7 +164,7 @@ def init(seed):
         format = SeedFormat.COMPOSITE
     # Now set up TritonDSE
     config = Config(coverage_strategy = CoverageStrategy.PATH,
-                    debug = is_debug,
+    #                debug = is_debug,
                     pipe_stdout = is_debug,
                     pipe_stderr = is_debug,
                     execution_timeout = 1,
diff --git a/custom_mutators/examples/README.md b/custom_mutators/examples/README.md
index 655f7a5e..112db243 100644
--- a/custom_mutators/examples/README.md
+++ b/custom_mutators/examples/README.md
@@ -33,3 +33,6 @@ like surgical_havoc_mutate() that allow to perform a randomly chosen
 mutation from a subset of the havoc mutations.
 If you do so, you have to specify -I /path/to/AFLplusplus/include when
 compiling.
+
+elf_header_mutator.c - example ELF header mutator based on 
+ [LibGolf](https://github.com/xcellerator/libgolf/)
diff --git a/custom_mutators/examples/elf_header_mutator.c b/custom_mutators/examples/elf_header_mutator.c
new file mode 100644
index 00000000..b985257a
--- /dev/null
+++ b/custom_mutators/examples/elf_header_mutator.c
@@ -0,0 +1,679 @@
+/*
+   AFL++ Custom Mutator for ELF Headers
+   Written by @echel0n <melih.sahin@protonmail.com>
+   based on libgolf.h by @xcellerator
+   $ gcc -O3 -fPIC -shared -o elf_mutator.so -I ~/AFLplusplus/include/
+ */
+#include "afl-fuzz.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <linux/elf.h>
+
+/* EI_ABIVERSION isn't used anymore and elf.h defines EI_PAD to be 0x09 */
+#define EI_ABIVERSION 0x08
+#define EI_PAD 0x09
+/* Define the Architecture and ISA constants to match those in <linux/elf.h> */
+#define X86_64 EM_X86_64
+#define ARM32 EM_ARM
+#define AARCH64 EM_AARCH64
+#define uchar unsigned char
+#define DATA_SIZE 0x100
+
+/*
+ * The ELF and Program headers are different sizes depending on 32- and 64-bit
+ * architectures
+ * taken from libgolf.h
+ */
+#define EHDR_T(x) Elf##x##_Ehdr
+#define PHDR_T(x) Elf##x##_Phdr
+#define EHDR(x) ehdr##x
+#define PHDR(x) phdr##x
+#define GET_EHDR(x) (&(elf_ptr->EHDR(x)));
+#define GET_PHDR(x) (&(elf_ptr->PHDR(x)));
+#define REF_EHDR(b, x) ((Elf##b##_Ehdr *)ehdr)->x
+#define REF_PHDR(b, x) ((Elf##b##_Phdr *)phdr)->x
+int ehdr_size;
+int phdr_size;
+/*
+ * This struct holds the bytes that will be executed, and the size.
+ */
+typedef struct text_segment {
+
+  size_t         text_size;
+  unsigned char *text_segment;
+
+} TextSegment;
+
+// example shellcode that exits
+// taken from libgolf.h
+unsigned char buf[] = {0xb0, 0x3c, 0x31, 0xff, 0x0f, 0x05};
+
+/*
+ * This is the raw ELF file
+ * - EHDR(xx) is the ELF header
+ * - PHDR(xx) is the program header
+ * - text is the text segment
+ * - filename is the name of the golf'd binary
+ * - isa is the target architecture (X86_64, ARM32, AARCH64)
+ * taken from libgolf.h
+ */
+typedef struct rawbinary_t {
+
+  EHDR_T(32) EHDR(32);
+  PHDR_T(32) PHDR(32);
+  EHDR_T(64) EHDR(64);
+  PHDR_T(64) PHDR(64);
+  TextSegment text;
+  char       *filename;
+  int         isa;
+
+} RawBinary;
+
+/*
+ * Copy an E_IDENT array into the corresponding fields in the ELF header
+ * Called by populate_ehdr()
+ * taken from libgolf.h
+ */
+int populate_e_ident(RawBinary *elf_ptr, unsigned char e_ident[]) {
+
+  int i;
+  /* Depending on whether the target ISA is 32- or 64-bit, set e_ident */
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+    case AARCH64:
+      for (i = 0; i < EI_NIDENT; i++)
+        elf_ptr->EHDR(64).e_ident[i] = e_ident[i];
+      break;
+    case ARM32:
+      for (i = 0; i < EI_NIDENT; i++)
+        elf_ptr->EHDR(32).e_ident[i] = e_ident[i];
+      break;
+    default:
+      exit(1);
+
+  }
+
+  return 0;
+
+}
+
+/*
+ * Copy bytes from buf[] array into text_segment in ELF struct
+ * taken from libgolf.h
+ */
+int copy_text_segment(RawBinary *elf_ptr, unsigned char buf[], int text_size) {
+
+  int i;
+
+  /* Set size of text segment and allocate the buffer */
+  elf_ptr->text.text_size = text_size;
+  elf_ptr->text.text_segment =
+      malloc(elf_ptr->text.text_size * sizeof(unsigned char));
+
+  /* Copy the bytes into the text segment buffer */
+  for (i = 0; i < elf_ptr->text.text_size; i++) {
+
+    elf_ptr->text.text_segment[i] = buf[i];
+
+  }
+
+}
+
+/*
+ * Populate the ELF Header with sane values
+ * Returns a pointer to an EHDR struct
+ * taken from libgolf.h
+ */
+void *populate_ehdr(RawBinary *elf_ptr) {
+
+  /*
+   * Set ehdr_size and phdr_size. Determined by whether target ISA is 32- or
+   * 64-bit.
+   */
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+    case AARCH64:
+      ehdr_size = sizeof(EHDR_T(64));
+      phdr_size = sizeof(PHDR_T(64));
+      break;
+    case ARM32:
+      ehdr_size = sizeof(EHDR_T(32));
+      phdr_size = sizeof(PHDR_T(32));
+      break;
+    default:
+      exit(1);
+
+  };
+
+  /* Start with the E_IDENT area at the top of the file */
+  unsigned char e_ident[EI_NIDENT] = {0};
+
+  /* Magic Bytes */
+  e_ident[EI_MAG0] = 0x7F;
+  e_ident[EI_MAG1] = 0x45;  // E
+  e_ident[EI_MAG2] = 0x4C;  // L
+  e_ident[EI_MAG3] = 0x46;  // F
+
+  /*
+   * EI_CLASS denotes the architecture:
+   * ELFCLASS32: 0x01
+   * ELFCLASS64: 0x02
+   */
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+    case AARCH64:
+      e_ident[EI_CLASS] = ELFCLASS64;
+      break;
+    case ARM32:
+      e_ident[EI_CLASS] = ELFCLASS32;
+      break;
+    default:
+      exit(1);
+
+  }
+
+  /*
+   * EI_DATA denotes the endianness:
+   * ELFDATA2LSB:   0x01
+   * ELFDATA2MSB:   0x02
+   */
+  e_ident[EI_DATA] = ELFDATA2LSB;
+
+  /* EI_VERSION is always 0x01 */
+  e_ident[EI_VERSION] = EV_CURRENT;
+
+  /*
+   * EI_OSABI defines the target OS. Ignored by most modern ELF parsers.
+   */
+  e_ident[EI_OSABI] = ELFOSABI_NONE;
+
+  /* EI_ABIVERSION was for sub-classification. Un-defined since Linux 2.6 */
+  e_ident[EI_ABIVERSION] = 0x00;
+
+  /* EI_PAD is currently unused */
+  e_ident[EI_PAD] = 0x00;
+
+  /* Copy the E_IDENT section to the ELF struct */
+  populate_e_ident(elf_ptr, e_ident);
+
+  /*
+   * The remainder of the ELF header following E_IDENT follows.
+   *
+   * ehdr is a pointer to either an Elf32_Edhr, or Elf64_Ehdr struct.
+   */
+  void *ehdr = NULL;
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+    case AARCH64:
+      ehdr = (&(elf_ptr->EHDR(64)));
+      break;
+    case ARM32:
+      ehdr = (&(elf_ptr->EHDR(32)));
+      break;
+    default:
+      exit(1);
+
+  }
+
+  /*
+   * Depending on whether the ISA is 32- or 64-bit determines the size of
+   * many of the fields in the ELF Header. This switch case deals with it.
+   */
+  switch (elf_ptr->isa) {
+
+    // 64-Bit ISAs
+    case X86_64:
+    case AARCH64:
+      /*
+       * e_type specifies what kind of ELF file this is:
+       * ET_NONE:         0x00    // Unknown Type
+       * ET_REL:          0x01    // Relocatable
+       * ET_EXEC:         0x02    // Executable File
+       * ET_DYN:          0x03    // Shared Object
+       * ET_CORE:         0x04    // Core Dump
+       */
+      REF_EHDR(64, e_type) = ET_EXEC;  // 0x0002
+
+      /* e_machine specifies the target ISA */
+      REF_EHDR(64, e_machine) = elf_ptr->isa;
+
+      /* e_version is always set of 0x01 for the original ELF spec */
+      REF_EHDR(64, e_version) = EV_CURRENT;  // 0x00000001
+
+      /*
+       * e_entry is the memory address of the entry point
+       * Set by set_entry_point() after p_vaddr is set in the phdr
+       */
+      REF_EHDR(64, e_entry) = 0x0;
+
+      /*
+       * e_phoff points to the start of the program header, which
+       * immediately follows the ELF header
+       */
+      REF_EHDR(64, e_phoff) = ehdr_size;
+
+      /* e_shoff points to the start of the section header table */
+      REF_EHDR(64, e_shoff) = 0x00;
+
+      /* e_flags is architecture dependent */
+      REF_EHDR(64, e_flags) = 0x0;
+
+      /* e_ehsize contains the size of the ELF header */
+      REF_EHDR(64, e_ehsize) = ehdr_size;
+
+      /* e_phentsize is the size of the program header */
+      REF_EHDR(64, e_phentsize) = phdr_size;
+
+      /*
+       * e_phnum contains the number of entries in the program header
+       * e_phnum * e_phentsize = size of program header table
+       */
+      REF_EHDR(64, e_phnum) = 0x1;
+
+      /* e_shentsize contains the size of a section header entry */
+      REF_EHDR(64, e_shentsize) = 0x0;
+
+      /*
+       * e_shnum contains the number of entries in the section header
+       * e_shnum * e_shentsize = size of section header table
+       */
+      REF_EHDR(64, e_shnum) = 0x0;
+
+      /*
+       * e_shstrndx contains the index of the section header table that
+       * contains the section names
+       */
+      REF_EHDR(64, e_shstrndx) = 0x0;
+
+      break;
+    // 32-Bit ISAs
+    case ARM32:
+      /*
+       * e_type specifies what kind of ELF file this is:
+       * ET_NONE:         0x00    // Unknown Type
+       * ET_REL:          0x01    // Relocatable
+       * ET_EXEC:         0x02    // Executable File
+       * ET_DYN:          0x03    // Shared Object
+       * ET_CORE:         0x04    // Core Dump
+       */
+      REF_EHDR(32, e_type) = ET_EXEC;  // 0x0002
+
+      /* e_machine specifies the target ISA */
+      REF_EHDR(32, e_machine) = elf_ptr->isa;
+
+      /* e_version is always set of 0x01 for the original ELF spec */
+      REF_EHDR(32, e_version) = EV_CURRENT;  // 0x00000001
+
+      /*
+       * e_entry is the memory address of the entry point
+       * Set by set_entry_point() after p_vaddr is set in the phdr
+       */
+      REF_EHDR(32, e_entry) = 0x0;
+
+      /*
+       * e_phoff points to the start of the program header, which
+       * immediately follows the ELF header
+       */
+      REF_EHDR(32, e_phoff) = ehdr_size;
+
+      /* e_shoff points to the start of the section header table */
+      REF_EHDR(32, e_shoff) = 0x0i;
+
+      /* e_flags is architecture dependent */
+      REF_EHDR(32, e_flags) = 0x0;
+
+      /* e_ehsize contains the size of the ELF header */
+      REF_EHDR(32, e_ehsize) = ehdr_size;
+
+      /* e_phentsize is the size of the program header */
+      REF_EHDR(32, e_phentsize) = phdr_size;
+
+      /*
+       * e_phnum contains the number of entries in the program header
+       * e_phnum * e_phentsize = size of program header table
+       */
+      REF_EHDR(32, e_phnum) = 0x1;
+
+      /* e_shentsize contains the size of a section header entry */
+      REF_EHDR(32, e_shentsize) = 0x0;
+
+      /*
+       * e_shnum contains the number of entries in the section header
+       * e_shnum * e_shentsize = size of section header table
+       */
+      REF_EHDR(32, e_shnum) = 0x0;
+
+      /*
+       * e_shstrndx contains the index of the section header table that
+       * contains the section names
+       */
+      REF_EHDR(32, e_shnum) = 0x0;
+
+      break;
+
+  }
+
+  return ehdr;
+
+}
+
+/*
+ * Populate the program headers with sane values
+ * Returns a pointer to a PHDR struct
+ * taken from libgolf.h
+ */
+void *populate_phdr(RawBinary *elf_ptr) {
+
+  /*
+   * All offsets are relative to the start of the program header (0x40)
+   *
+   * phdr is a pointer to either an Elf32_Phdr, or Elf64_Phdr struct.
+   */
+  void *phdr = NULL;
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+    case AARCH64:
+      phdr = (&(elf_ptr->PHDR(64)));
+      break;
+    case ARM32:
+      phdr = (&(elf_ptr->PHDR(32)));
+      break;
+    default:
+      exit(1);
+
+  }
+
+  /*
+   * Depending on whether the ISA is 32- or 64-bit determines the size of
+   * many of the fields in the Progra Header. This switch case deals with it.
+   */
+  switch (elf_ptr->isa) {
+
+    // 64-Bit ISAs
+    case X86_64:
+    case AARCH64:
+      /*
+       * p_type identifies what type of segment this is
+       * PT_NULL:         0x0     // Unused
+       * PT_LOAD:         0x1     // Loadable Segment
+       * PT_DYNAMIC:      0x2     // Dynamic Linker Information
+       * PT_INTERP:       0x3     // Interpreter Information
+       * PT_NOTE:         0x4     // Auxiliary Information
+       * PT_SHLIB:        0x5     // Reserved
+       * PT_PHDR:         0x6     // Segment with Program Header
+       * PT_TLS:          0x7     // Thread Local Storage
+       */
+      REF_PHDR(64, p_type) = PT_LOAD;  // 0x1
+
+      /*
+       * p_flags defines permissions for this section
+       * PF_R:    0x4     // Read
+       * PF_W:    0x2     // Write
+       * PF_X:    0x1     // Execute
+       */
+      REF_PHDR(64, p_flags) = PF_R | PF_X;  // 0x5
+
+      /*
+       * p_offset is the offset in the file image (relative to the start
+       * of the program header) for this segment.
+       */
+      REF_PHDR(64, p_offset) = 0x0;
+
+      /*
+       * p_vaddr is the virtual address where this segment should be loaded
+       * p_paddr is for the physical address (unused by System V)
+       */
+      REF_PHDR(64, p_vaddr) = 0x400000;
+      REF_PHDR(64, p_paddr) = 0x400000;
+
+      /*
+       * p_filesz is the size of the segment in the file image
+       * p_memsz is the size of the segment in memory
+       *
+       * Note: p_filesz doesn't have to equal p_memsz
+       */
+      REF_PHDR(64, p_filesz) = elf_ptr->text.text_size;
+      REF_PHDR(64, p_memsz) = elf_ptr->text.text_size;
+
+      break;
+    // 32-Bit ISAs
+    case ARM32:
+      /*
+       * p_type identifies what type of segment this is
+       * PT_NULL:         0x0     // Unused
+       * PT_LOAD:         0x1     // Loadable Segment
+       * PT_DYNAMIC:      0x2     // Dynamic Linker Information
+       * PT_INTERP:       0x3     // Interpreter Information
+       * PT_NOTE:         0x4     // Auxiliary Information
+       * PT_SHLIB:        0x5     // Reserved
+       * PT_PHDR:         0x6     // Segment with Program Header
+       * PT_TLS:          0x7     // Thread Local Storage
+       */
+      REF_PHDR(32, p_type) = PT_LOAD;  // 0x1
+
+      /*
+       * p_flags defines permissions for this section
+       * PF_R:    0x4     // Read
+       * PF_W:    0x2     // Write
+       * PF_X:    0x1     // Execute
+       */
+      REF_PHDR(32, p_flags) = PF_R | PF_X;  // 0x5
+
+      /*
+       * p_offset is the offset in the file image (relative to the start
+       * of the program header) for this segment.
+       */
+      REF_PHDR(32, p_offset) = 0x0;
+
+      /*
+       * p_vaddr is the virtual address where this segment should be loaded
+       * p_paddr is for the physical address (unused by System V)
+       */
+      REF_PHDR(32, p_vaddr) = 0x10000;
+      REF_PHDR(32, p_paddr) = 0x10000;
+
+      /*
+       * p_filesz is the size of the segment in the file image
+       * p_memsz is the size of the segment in memory
+       *
+       * Note: p_filesz doesn't have to equal p_memsz
+       */
+      REF_PHDR(32, p_filesz) = elf_ptr->text.text_size;
+      REF_PHDR(32, p_memsz) = elf_ptr->text.text_size;
+
+      break;
+    default:
+      exit(1);
+
+  }
+
+  /*
+   * p_align is the memory alignment
+   *
+   * Note: p_vaddr = p_offset % p_align
+   */
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+      REF_PHDR(64, p_align) = 0x400000;
+      break;
+    case ARM32:
+      REF_PHDR(32, p_align) = 0x10000;
+      break;
+    case AARCH64:
+      REF_PHDR(64, p_align) = 0x400000;
+      break;
+
+  }
+
+  return phdr;
+
+}
+
+/*
+ * e_entry depends on p_vaddr, so has to be set after populate_ehdr()
+ * and populate_phdr() have been called.
+ * taken from libgolf.h
+ */
+int set_entry_point(RawBinary *elf_ptr) {
+
+  /*
+   * Once the whole ELF file is copied into memory, control is handed to
+   * e_entry. Relative to the process's virtual memory address, the .text
+   * segment will be located immediately after the ELF and program header.
+   *
+   * ehdr and phdr are pointers to the ELF and Program headers respectively.
+   * The switch case casts and assigns them to the correct fields of the ELF
+   * struct, then sets ehdr->e_entry.
+   */
+  void *ehdr, *phdr;
+
+  switch (elf_ptr->isa) {
+
+    case X86_64:
+    case AARCH64:
+      ehdr = GET_EHDR(64);
+      phdr = GET_PHDR(64);
+      REF_EHDR(64, e_entry) = REF_PHDR(64, p_vaddr) + ehdr_size + phdr_size;
+      break;
+    case ARM32:
+      ehdr = GET_EHDR(32);
+      phdr = GET_PHDR(32);
+      REF_EHDR(32, e_entry) = REF_PHDR(32, p_vaddr) + ehdr_size + phdr_size;
+      break;
+    default:
+      exit(1);
+
+  }
+
+  return 0;
+
+}
+
+typedef struct my_mutator {
+
+  afl_state_t *afl;
+  size_t       trim_size_current;
+  int          trimmming_steps;
+  int          cur_step;
+  u8          *mutated_out, *post_process_buf, *trim_buf;
+
+} my_mutator_t;
+
+my_mutator_t *afl_custom_init(afl_state_t *afl, unsigned int seed) {
+
+  srand(seed);  // needed also by surgical_havoc_mutate()
+  my_mutator_t *data = calloc(1, sizeof(my_mutator_t));
+  if (!data) {
+
+    perror("afl_custom_init alloc");
+    return NULL;
+
+  }
+
+  if ((data->mutated_out = (u8 *)malloc(MAX_FILE)) == NULL) {
+
+    perror("afl_custom_init malloc");
+    return NULL;
+
+  }
+
+  if ((data->post_process_buf = (u8 *)malloc(MAX_FILE)) == NULL) {
+
+    perror("afl_custom_init malloc");
+    return NULL;
+
+  }
+
+  if ((data->trim_buf = (u8 *)malloc(MAX_FILE)) == NULL) {
+
+    perror("afl_custom_init malloc");
+    return NULL;
+
+  }
+
+  data->afl = afl;
+  return data;
+
+}
+
+size_t afl_custom_fuzz(my_mutator_t *data, uint8_t *in_buf, size_t buf_size,
+                       u8 **out_buf, uint8_t *add_buf,
+                       size_t add_buf_size,  // add_buf can be NULL
+                       size_t max_size) {
+
+  RawBinary  elf_obj;
+  RawBinary *elf = &elf_obj;
+  elf->isa = 62;
+  Elf64_Ehdr *ehdr;
+  Elf64_Phdr *phdr;
+  copy_text_segment(elf, buf, sizeof(buf));
+  ehdr = populate_ehdr(elf);
+  phdr = populate_phdr(elf);
+  set_entry_point(elf);
+
+  size_t mutated_size = ehdr_size + phdr_size + elf->text.text_size;
+  int    pos = 0;
+  // example fields
+  ehdr->e_ident[EI_CLASS] = (uint8_t *)(in_buf + pos++);
+  ehdr->e_ident[EI_DATA] = (uint8_t *)(in_buf + pos++);
+  ehdr->e_ident[EI_VERSION] = (uint8_t *)(in_buf + pos++);
+  ehdr->e_ident[EI_OSABI] = (uint8_t *)(in_buf + pos++);
+  for (int i = 0x8; i < 0x10; ++i) {
+
+    (ehdr->e_ident)[i] = (uint8_t *)(in_buf + pos++);
+
+  }
+
+  ehdr->e_version = (uint32_t *)(in_buf + pos);
+  pos += 4;
+  // sections headers
+  ehdr->e_shoff = (uint64_t *)(in_buf + pos);
+  pos += 8;
+  ehdr->e_shentsize = (uint16_t *)(in_buf + pos);
+  pos += 2;
+  ehdr->e_shnum = (uint16_t *)(in_buf + pos);
+  pos += 2;
+  ehdr->e_shstrndx = (uint16_t *)(in_buf + pos);
+  pos += 2;
+  ehdr->e_flags = (uint32_t *)(in_buf + pos);
+  pos += 4;
+  // physical addr
+  phdr->p_paddr = (uint64_t *)(in_buf + pos);
+  pos += 8;
+  phdr->p_align = (uint64_t *)(in_buf + pos);
+  pos += 8;
+
+  /* mimic GEN_ELF()
+   * Write:
+   * - ELF Header
+   * - Program Header
+   * - Text Segment
+   */
+  memcpy(data->mutated_out, ehdr, ehdr_size);
+  memcpy(data->mutated_out + ehdr_size, phdr, phdr_size);
+  memcpy(data->mutated_out + ehdr_size + phdr_size, elf->text.text_segment,
+         elf->text.text_size);
+
+  *out_buf = data->mutated_out;
+  return mutated_size;
+
+}
+
+void afl_custom_deinit(my_mutator_t *data) {
+
+  free(data->post_process_buf);
+  free(data->mutated_out);
+  free(data->trim_buf);
+  free(data);
+
+}
+