OpenBSD 2.9,2.8 vulnerable to localroot compromise

Georgi Guninski reports that there
is local root compromise in OpenBSD
2.9, 2.8 due to a race probably in
the kernel. By forking a few
process it is possible to attach to
+s pid with ptrace. The process
seems to be in a strange state when
it is attached. Contrary to the man
info PT_DETACH allows specifying an
address to which execution is
continued. This is quite similar to
the linux kernel race several
months ago and would allow
unauthorized access to compromise
ROOT.

OpenBSD 2.9,2.8 local root compromise
Posted on 15.6.2001

Georgi Guninski security advisory #47, 2001

OpenBSD 2.9,2.8 local root compromise

Systems affected:
OpenBSD 2.9,2.8
Have not tested on other OSes but they may be vulnerable

Risk: High
Date: 14 June 2001

Legal Notice:
This Advisory is Copyright (c) 2001 Georgi Guninski. You may distribute it unmodified. You may not modify it and distribute it or distribute parts of it without the author's written permission.

Disclaimer:
The information in this advisory is believed to be true based on experiments though it may be false. The opinions expressed in this advisory and program are my own and not of any company. The usual standard disclaimer applies, especially the fact that Georgi Guninski is not liable for any damages caused by direct or indirect use of the information or functionality provided by this advisory or program. Georgi Guninski bears no responsibility for content or misuse of this advisory or program or any derivatives thereof.

Description:
There is local root compromise in OpenBSD 2.9, 2.8 due to a race probably in the kernel. This is quite similar to the linux kernel race several months ago.

Details:
By forking a few process it is possible to attach to +s pid with ptrace. The process seems to be in a strange state when it is attached. Contrary to the man info PT_DETACH allows specifying an address to which execution is continued.

Exploit:

http://www.guninski.com/vvopenbsd.c

Workaround:
Don't know

Vendor status:
OpenBSD was informed on 9 June 2001.

Regards,
Georgi Guninski
http://www.guninski.com