Twenty Year Anniversary

openbsdDoS.txt

openbsdDoS.txt
Posted Aug 30, 2004
Authored by Vafa Izadinia

OpenBSD 3.5 is susceptible to a remote denial of service attack via a single ICMP echo request when set up as a gateway. Patch from OpenBSD included.

tags | advisory, remote, denial of service
systems | openbsd
MD5 | daeff80712162785ed832644720c5da5

openbsdDoS.txt

Change Mirror Download

Hi, I have posted this vulnerability note to CERT and gotten no
response. It is remotely exploitable, but since it requires commands

to be executed as root on the gateway machine, it is unlikely to cause

any unplanned disruption.

OpenBSD was contacted, and they provided a patch within 12 hours.

-=-=-=-
Description
-=-=-=-
An OpenBSD 3.5 machine, configured as a gateway (2 NICs --Net A,
and Net B), once bridging has been activated, and the link2 option
given (for IPSec processing), is vulnerable to a single ICMP echo
request sent from a machine on interface A's network sent to a machine

on interface B's network, causing it to crash. No core file is
generated. If the DDB_PANIC option is set, the machine reboots upon
receipt of the ICMP echo request.
-=-=-=-

Commands (assuming fxp0 and fxp1 are the two interfaces):

# ifconfig bridge0 create
# brconfig bridge0 add fxp0 add fxp1 up
# brconfig bridge0 link2

the machine is now vulnerable to a single ping from a machine on NetA

destined to a machine in NetB.

The problem was observed on a test network, and reproduced on a VMWare

network. Screen-shots of the crash on the VMWare setup are available.


OpenBSD's patch follows.

'='='=' Begin Patch ='='='= Remove this line '='='='

Index: sys/net/if_bridge.c ===================================================================
RCS file: /cvs/src/sys/net/if_bridge.c,v
retrieving revision 1.136
diff -u -r1.136 if_bridge.c
--- sys/net/if_bridge.c 21 Jun 2004 23:50:36 -0000 1.136
+++ sys/net/if_bridge.c 18 Aug 2004 09:29:04 -0000
@@ -2275,9 +2275,9 @@
splx(s);
return (1);
} else {
+ splx(s);
skiplookup:
/* XXX do an input policy lookup */
- splx(s);
return (0);
}
} else { /* Outgoing from the bridge. */


'='='=' End Patch ='='='= Remove this line '='='='

cheers,

Vafa Izadinia.

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

File Archive:

November 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Nov 1st
    10 Files
  • 2
    Nov 2nd
    15 Files
  • 3
    Nov 3rd
    2 Files
  • 4
    Nov 4th
    2 Files
  • 5
    Nov 5th
    32 Files
  • 6
    Nov 6th
    27 Files
  • 7
    Nov 7th
    8 Files
  • 8
    Nov 8th
    9 Files
  • 9
    Nov 9th
    17 Files
  • 10
    Nov 10th
    2 Files
  • 11
    Nov 11th
    2 Files
  • 12
    Nov 12th
    32 Files
  • 13
    Nov 13th
    0 Files
  • 14
    Nov 14th
    0 Files
  • 15
    Nov 15th
    0 Files
  • 16
    Nov 16th
    0 Files
  • 17
    Nov 17th
    0 Files
  • 18
    Nov 18th
    0 Files
  • 19
    Nov 19th
    0 Files
  • 20
    Nov 20th
    0 Files
  • 21
    Nov 21st
    0 Files
  • 22
    Nov 22nd
    0 Files
  • 23
    Nov 23rd
    0 Files
  • 24
    Nov 24th
    0 Files
  • 25
    Nov 25th
    0 Files
  • 26
    Nov 26th
    0 Files
  • 27
    Nov 27th
    0 Files
  • 28
    Nov 28th
    0 Files
  • 29
    Nov 29th
    0 Files
  • 30
    Nov 30th
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2018 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close