diff options
| -rw-r--r-- | crypter/.gitignore | 1 | ||||
| -rw-r--r-- | crypter/Makefile | 12 | ||||
| -rw-r--r-- | crypter/simple_encoder.c | 56 | ||||
| -rw-r--r-- | sc-test.c | 5 |
4 files changed, 53 insertions, 21 deletions
diff --git a/crypter/.gitignore b/crypter/.gitignore index 424c745..f69e226 100644 --- a/crypter/.gitignore +++ b/crypter/.gitignore @@ -1 +1,2 @@ *.h +simple_encoder diff --git a/crypter/Makefile b/crypter/Makefile index c009e2b..57409a9 100644 --- a/crypter/Makefile +++ b/crypter/Makefile @@ -3,7 +3,7 @@ ASM := nasm CC := gcc LD := ld XXD := xxd -CFLAGS = -c -Wall -fpic -Os +CFLAGS = -Wall -fpic -Os LDFLAGS = SUBDIR ?= . TARGETS = $(patsubst %.asm,%.o,$(wildcard $(SUBDIR)/*.asm)) $(patsubst %.c,%.o,$(wildcard $(SUBDIR)/*.c)) @@ -20,13 +20,9 @@ all: $(TARGETS) ifneq ($(SCC),yes) $(error Please run 'make' in the main directory) endif -ifneq ($(shell if [ -r "$<" ]; then echo "yes"; else echo "no"; fi),yes) - $(error Necessary file '$<' not found) -endif - -$(shell ../sc-test -p `cat "$<" | sed -n 's/.*#DECODER=//p'` > $(patsubst %.o,%.h,$@)) - -$(shell ../sc-test -p `cat "$<" | sed -n 's/.*#DECODER=//p'` > $(patsubst %.o,%.h,$@)) - $(CC) $(CFLAGS) -D_USE_CFG -o $@ $< - $(LD) $(LDFLAGS) $@ -o $(patsubst %.o,%,$@) + -$(shell $(SCDIR)/sc-test -p $(SUBDIR)/`cat "$<" | sed -n 's/.*#DECODER=//p'` | sed 's/shellcode/decoder/' > $(patsubst %.o,%.h,$@)) + -$(shell $(SCDIR)/sc-test -p $(SUBDIR)/`cat "$<" | sed -n 's/.*#SHELLCODE=//p'` >> $(patsubst %.o,%.h,$@)) + $(CC) $(CFLAGS) -D_USE_CFG -o $(patsubst %.c,%,$<) $< clean: $(RM) -f $(patsubst %.o,%,$(TARGETS)) $(TARGETS) $(patsubst %.o,%.h,$(TARGETS)) diff --git a/crypter/simple_encoder.c b/crypter/simple_encoder.c index 791a20f..bbedaf3 100644 --- a/crypter/simple_encoder.c +++ b/crypter/simple_encoder.c @@ -1,5 +1,5 @@ // #DECODER=./simple_decoder.o -// #SHELLCODE=../hello.o +// #SHELLCODE=../shellcode/hello.o #include <stdio.h> #include <string.h> #include <sys/time.h> @@ -30,12 +30,12 @@ getnumber(int n) } void -print_code(char *data) +print_code(const char *name, char *data, int len) { int i,l = 15; - printf("\n\nunsigned long int lshellcode = %lu;\nchar shellcode[] = \n", (unsigned long int) strlen(data)); - for (i = 0; i < strlen(data); i++) { + printf("unsigned long int l%s = %lu;\nchar %s[] = \n", name, (unsigned long int) strlen(data), name); + for (i = 0; i < len; i++) { if (l >= 15) { if (i) { printf("\"\n"); @@ -46,19 +46,51 @@ print_code(char *data) ++l; printf("\\x%02x", ((unsigned char *)data)[i]); } - printf("\";\n\n\n"); + printf("\";\n\n"); } int main(int argc, char **argv) { -// char decoder[] = _DECODER; - int count, number = getnumber(_CRYPTVAL), nullbyte = 0, ldecoder = strlen(decoder), lshellcode = strlen(shellcode); + int i, npos = 0, number = getnumber(_CRYPTVAL), nullbyte = 0; + int ldecoder = sizeof(decoder)-1; /* last byte is '\x00' */ + int lshellcode = sizeof(shellcode)-1; /* same as above */ + int first_arg = 1; char *result; - printf("Using value %d to encode the shellcode.\n", number); - printf("*** PRINT SHELLCODE\n"); - print_code(shellcode); - printf("*** PRINT DECODER\n"); - print_code(decoder); + printf("/* Using value %d to encode the shellcode. */\n", number); + printf("/* PRINT SHELLCODE */\n"); + print_code("shellcode", shellcode, lshellcode); + printf("/* PRINT DECODER */\n"); + print_code("decoder", decoder, ldecoder); + + for (i = 0; i < ldecoder; i++) { + if (decoder[i] == '\x00') { + if (first_arg) { + decoder[i] = lshellcode; + first_arg = 0; + } else { + decoder[i] = (unsigned char) number; + npos = i; + } + printf("// decoder[%d] = %u (%02x)\n", i, (unsigned char) decoder[i], (unsigned char) decoder[i]); + } + } + + do { + if (nullbyte == 1) { + number = getnumber(10); + decoder[npos] += number; + nullbyte = 0; + } + + for (i = 0; i < lshellcode; i++) { + shellcode[i] += number; + if (shellcode[i] == '\x00') { + nullbyte = 1; + } + } + } while (nullbyte == 1); + + return (0); } @@ -44,7 +44,10 @@ main(int argc, char **argv) { memset(&sbuf, '\0', sizeof(struct stat)); if (argc < 3) usage(argv[0]); - if (stat(argv[2], &sbuf)) barf("failed to stat file"); + if (stat(argv[2], &sbuf)) { + fprintf(stderr, "file: %s\n", argv[2]); + barf("failed to stat"); + } flen = (long) sbuf.st_size; if (!(code = calloc(1, flen))) barf("failed to grab memory"); if (!(fp = fopen(argv[2], "rb"))) barf("failed to open file"); |