1 files changed, 65 insertions, 0 deletions

diff --git a/crash/header_screwer.c b/crash/header_screwer.c
new file mode 100644
index 0000000..735aecd
--- /dev/null
+++ b/crash/header_screwer.c
@@ -0,0 +1,65 @@
+/*
+ * Elf header screwer, based on an idea of svenka's crackme, named Thellurik (http://crackmes.de/users/svenka/thellurik/)
+ * Unfortunately for me, ioactive was quicker than me : http://blog.ioactive.com/2012/12/striking-back-gdb-and-ida-debuggers.html
+ * Kudos to them !
+ *
+ */
+
+
+#include <stdio.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <elf.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/procfs.h>
+#include <fcntl.h>
+
+
+int main(int argc, char** argv){
+    int f;
+    static Elf32_Ehdr* header;
+
+    printf(".: Elf corrupt :.\n");
+
+    if(argc < 2){
+        printf("Usage: %s file", argv[0]);
+        return 1;
+    }
+
+    if((f = open(argv[1], O_RDWR)) < 0){
+        perror("open");
+        return 1;
+    }
+
+    //MAP_SHARED is required to actually update the file
+    if((header = (Elf32_Ehdr *) mmap(NULL, sizeof(header), PROT_READ | PROT_WRITE, MAP_SHARED, f, 0)) == MAP_FAILED){
+        perror("mmap");
+        close(f);
+        return 1;
+    }
+
+    printf("[*] Current header values:\n");
+    printf("\te_shoff:%d\n\te_shnum:%d\n\te_shstrndx:%d\n",
+            header->e_shoff, header->e_shnum, header->e_shstrndx);
+
+    header->e_shoff = 0xffff;
+    header->e_shnum = 0xffff;
+    header->e_shstrndx = 0xffff;
+
+    printf("[*] Patched header values:\n");
+    printf("\te_shoff:%d\n\te_shnum:%d\n\te_shstrndx:%d\n",
+            header->e_shoff, header->e_shnum, header->e_shstrndx);
+
+    if(msync(NULL, 0, MS_SYNC) == -1){
+        perror("msync");
+        close(f);
+        return 1;
+    }
+
+    close(f);
+    munmap(header, 0);
+    printf("You should no more be able to run \"%s\" inside GDB\n", argv[1]);
+    return 0;
+}