generate payload from file

includes/woody.h

@@ -14,9 +14,14 @@
 #include <elf.h>
 #include <stdint.h>
 
-#define PAYLOAD "\x50\x57\x56\x52\x53\xbf\x01\x00\x00\x00\x48\x8d\x35\x16\x00\x00\x00\xba\x0a\x00\x00\x00\xb8\x01\x00\x00\x00\x0f\x05\x5b\x5a\x5e\x5f\x58\xe9\xd9\xff\xff\xff\x2e\x2e\x57\x4f\x4f\x44\x59\x2e\x2e\x0a"
 #define JUMP "\xe9"
 
+typedef struct payload
+{
+	char *payload;
+	size_t len;
+}	t_payload;
+
 typedef struct efl_content
 {
 	long unsigned int file_size;

print.s

@@ -1,32 +1,4 @@
-; bits 64
-; default rel
-; global _start
-
-; _start:
-; 		push rax
-; 		push rdi
-; 		push rsi
-; 		push rdx	
-; 		push rbx
-
-;         xor     eax, eax
-;         cdq
-;         mov     dl, 10
-;         inc     eax
-;         mov     edi, eax
-;         lea     rsi, [rel msg]
-;         syscall
-; 		pop rbx
-; 		pop rdx
-; 		pop rsi
-; 		pop rdi
-; 		pop rax
-; 		jmp 0x00000000
-		
-; msg     db "..WOODY..",10
-
 bits 64
-default rel
 global _start
 
 _start:
@@ -34,15 +6,18 @@ _start:
 		push rdi
 		push rsi
 		push rdx
-        push rbx
 
+		mov rdi, 1
+		mov rdi, 1
+		mov rdi, 1
+		mov rdi, 1
+		mov rdi, 1
 		mov rdi, 1
 		lea     rsi, [rel msg]
 		mov rdx, 10
 		mov rax, 1
 		syscall
 
-        pop rbx
 	    pop rdx
         pop rsi
         pop rdi

srcs/main.c

@@ -19,7 +19,7 @@ int get_elf_file(t_efl_content *woody)
         return EXIT_FAILURE;
     }
 	woody->file_size = off;
-	woody->file = mmap(NULL, woody->file_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	woody->file = mmap(NULL, woody->file_size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
     if (woody->file  == MAP_FAILED)
 	{
 		close(fd);

srcs/woody.c

@@ -59,10 +59,10 @@ void offset_sections(t_efl_content *woody, unsigned int from, unsigned int offse
 	}
 }
 
-size_t	create_codecave(t_efl_content *woody, Elf64_Phdr *load_segment)
+size_t	create_codecave(t_efl_content *woody, Elf64_Phdr *load_segment, t_payload *payload)
 {
 	const unsigned int page_size = 4096; // getpagesize(); not authorized
-	unsigned int padding_size = ((sizeof(PAYLOAD) / page_size) + 1) * page_size;
+	unsigned int padding_size = ((payload->len / page_size) + 1) * page_size;
 	unsigned int codecave_start = load_segment->p_offset + load_segment->p_filesz;
 	offset_sections(woody, codecave_start, padding_size);
 	char *new_woody = malloc(woody->file_size + padding_size);
@@ -80,23 +80,33 @@ size_t	create_codecave(t_efl_content *woody, Elf64_Phdr *load_segment)
 	return codecave_start;
 }
 
-
+t_payload *get_payload()
-int	insert_payload(t_efl_content *woody, size_t payload_position)
 {
-	char payload[] = PAYLOAD;
+	t_payload *payload = malloc(sizeof(t_payload));
-    size_t len_payload = sizeof(PAYLOAD) - 1;
+	if (!payload)
-	char *ptr = ft_strnstr_nullterminated(payload, JUMP, len_payload);
+		return NULL;
+	char buffer[1024];
+	int fd = open("payload", O_RDONLY);
+	payload->len = read(fd, buffer, 1024);
+	payload->payload = malloc(sizeof(char) * payload->len);
+	ft_memcpy(payload->payload, buffer, payload->len);
+	return payload;
+}
 
+int	insert_payload(t_efl_content *woody, t_payload *payload, size_t payload_position)
+{
+	char *ptr = ft_strnstr_nullterminated(payload->payload, JUMP, payload->len);
 	if (ptr)
 	{
-		int32_t jmp_index = ptr - payload; 
+		int32_t jmp_index = ptr - payload->payload; 
-		int32_t jump_value = ((payload_position + len_payload) - woody->Ehdr->e_entry) * -1;
+		int32_t jump_value = ((payload_position + payload->len) - woody->Ehdr->e_entry) * -1;
-		ft_memcpy(&payload[jmp_index + 1], &jump_value, sizeof(jump_value));
+
-		ft_memcpy(woody->file + payload_position, payload, len_payload);
+		ft_memcpy(&payload->payload[jmp_index + 1], &jump_value, sizeof(jump_value));
+		ft_memcpy(woody->file + payload_position, payload->payload, payload->len);
 
 		printf("Old entry : %ld (%lx)\n", woody->Ehdr->e_entry, woody->Ehdr->e_entry);
-		printf("Code_cave_start = %ld (%lx)\n", payload_position, payload_position);
+		printf("Code cave start = %ld (%lx)\n", payload_position, payload_position);
-		printf("Payload size = %ld (%lx)\n", len_payload, len_payload);
+		printf("Payload size = %ld (%lx)\n", payload->len, payload->len);
 		printf("Backwar d offset = %d (%x)\n", jump_value, jump_value);
 		
 		return EXIT_SUCCESS;
@@ -106,29 +116,30 @@ int	insert_payload(t_efl_content *woody, size_t payload_position)
 
 void	inject(t_efl_content *woody)
 {
-    size_t len_payload = sizeof(PAYLOAD) - 1;
+	t_payload *payload = get_payload();
 
 	int i = get_load_segment(woody, 0, true);	
 	int j = get_load_segment(woody, i + 1, false);
 	
-	
 	size_t code_cave_size = woody->Phdr[j].p_offset - (woody->Phdr[i].p_offset + woody->Phdr[i].p_filesz);
 	size_t payload_position;
+	printf("load position = : %ld (%lx)\n", woody->Phdr[i].p_offset, woody->Phdr[i].p_offset);
+	printf("load size = : %ld (%lx)\n", woody->Phdr[i].p_filesz, woody->Phdr[i].p_filesz);
 
-	if (code_cave_size > len_payload)
+	if (code_cave_size > payload->len) // inverse here to test the other technique
 	{
 		payload_position = woody->Phdr[i].p_offset + woody->Phdr[i].p_memsz;
 		printf("Code_cave_size = %ld (%lx)\n", code_cave_size, code_cave_size);
 	}
 	else
 	{
-		payload_position = create_codecave(woody, &woody->Phdr[i]);
+		payload_position = create_codecave(woody, &woody->Phdr[i], payload);
 	}
-	insert_payload(woody, payload_position);
+	insert_payload(woody, payload, payload_position);
 
 	woody->Ehdr->e_entry = payload_position;
-	woody->Phdr[i].p_filesz += len_payload;
+	woody->Phdr[i].p_filesz += payload->len;
-	woody->Phdr[i].p_memsz += len_payload;
+	woody->Phdr[i].p_memsz += payload->len;
 
 	printf("New entry = %ld (%lx)\n", woody->Ehdr->e_entry, woody->Ehdr->e_entry);
 }