Admin Security Web Site Technologies

DOS Attack from South Korea

Last week I witnessed a denial-of-service (DOS) attack against a web server. This is disconcerting to say the least. I felt by putting the information out in the open some leverage might be applied to the responsible party for that server or subnet.

The source of the attack was a single IP,

Some Details
The attack occurred July 31st.

It consisted of over 100,000 object accesses.

I do not see evidence of an actual hack.

It lasted about 10 hours, from 12:30 PM EST to 10:57 PM, with some few preliminary accesses starting at 4 AM before the onslaught at Noon.

Clearly some kind of tool was used. It is very aggressive around forms, doing lots of variations in its POST to the same form, over and over. Here’s one small snippet that gives the flavor: - - [31/Jul/2012:22:53:05 -0400] "POST /[omitted]/forgot_password.jsp../../../../../../../../../../etc/passwd/./././././././././././[pattern repeated - total URI is over 4000 characters!]

Then there’s the fishing around for files which I suppose if present may become a vector for attack, like these lines: - - [31/Jul/2012:12:31:47 -0400] "GET /qlc9tjIqjR.cfm HTTP/1.1" 404 292 "-" "Mozilla/4.0 (compa
tible; MSIE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:48 -0400] "GET /_vti_pvt/authors.pwd HTTP/1.1" 404 292 "-" "Mozilla/4.0
(compatible; MSIE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:47 -0400] "GET / HTTP/1.1" 200 9491 "-" "Mozilla/4.0 (compatible; MSIE 8
.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:48 -0400] "GET /crossdomain.xml HTTP/1.1" 404 292 "-" "Mozilla/4.0 (comp
atible; MSIE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:48 -0400] "GET /solr/select/?q=test HTTP/1.1" 404 292 "-" "Mozilla/4.0 (
compatible; MSIE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:47 -0400] "GET /inexistent_file_name.inexistent0123450987.cfm HTTP/1.1"
404 292 "-" "<script>alert(12345)</script>" "-" "-" - - [31/Jul/2012:12:31:47 -0400] "GET http://www.acunetix.wvs HTTP/1.1" 404 292 "-" "Mozilla/4.
0 (compatible; MSIE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:47 -0400] "GET /index HTTP/1.1" 404 292 "-" "Mozilla/4.0 (compatible; MS
IE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:47 -0400] "GET /server-info HTTP/1.1" 404 292 "-" "Mozilla/4.0 (compatib
le; MSIE 8.0; Windows NT 6.0)" "-" "-" - - [31/Jul/2012:12:31:48 -0400] "POST /_vti_bin/shtml.exe?_vti_rpc HTTP/1.1" 405 124 "-" "Mozi
lla/4.0 (compatible; MSIE 8.0; Windows NT 6.0)" "-" "-"

The line mentioning Acunetix is I think a key to understanding this attack. I think it is leaving a cookie crumb trail to let the attacked site know what tool was used: Acunetix WVS Free Edition scanner.

So it’s a semi-legitimate tool, or at least one openly referenced by Google. But in the hands of a malicious or simply ignorant user, such a tool actually does become a DOS weapon. Its aggressive POSTs often have consequences for back-end databases. A medium-duty site is typically not tuned to handle 8,000 POSTS per hour, which is the rate they came in – over two per second. So the site can be tied up servicing these POSTs and not have resources left over to handle legitimate requests.

To get some background on where this originated from and by whom, I did a whois search on ARIN, the main Internet address space registry. This told me that that address space has been delegated to APNIC, the ASIA-Pacific NIC. So I did a Whois search on APNIC. That showed me that in fact that range is in turn delegated to Korea NIC! So it’s off to the KRNIC and their whois… That in turn gave me the most specific information of all:

More specific assignment information is as follows.
[ Network Information ]
IPv4 Address       : - (/22)
Network Name       : SHINBIRO-INFRA
Organization Name  : ONSE Telecom
Organization ID    : ORG2324
Address            : 2F Bundang Center, Onse IDC, 235-230, 
Zip Code           : 448-500
Registration Date  : 20081107
Publishes          : Y
 See the Contact Info
[ Technical Contact Information ] Name : IP Manager Organization Name : ONSE Telecom Zip Code : 448-500 Phone : +82-2-1666-0120 E-Mail :
- KISA/KRNIC Whois Service -

Obviously it doesn’t get so specific that it tells me who owns the attacking host, but the mentioned subnet, is not too big, all things considered, so that’s quite specific compared to where we were when we started our journey. It seems that its administered by ONSE Telecom in South Korea.

I tried to contact them by email – the email bounced. I also wrote to, which also bounced.

KRNIC is run by KISA, which claims to be an Internet security enterprise (fat chance in my book). I filled out their online contact form – it consistently failed to accept my message, no matter how simple I made it.

At this point I decided that this is too many offenses. The owners of that subnet, are not playing by the rules of the Internet and they should be cut off from the Internet until they follow the rules.

So I set up rules to discard all packets from subnet and I recommend that others do the same on their web sites.

Amazon Cloud not very sophisticated with regards to security
I initially tried to take my own advice and sought to put the above subnet into a deny security rule on my Amazon cloud service. I work with firewalls and this sort of thing is commonplace and been around for well over 15 years. But you can’t do it on the Amazon Cloud security service! I was shocked. They have so many sophisticated services and have clearly thought out this “cloud thing” better than just about anyone, but they didn’t stop to listen to customer requests on this basic security issue – a allow all but these subnets type of capability.

A DOS was observed emanating from a host in South Korea using Acunetix’s free WVS scanner. The owner of the subnet does not post legitimate contact information and should be banned from Internet connectivity for this egregious behaviour which was perpetrated using its address space.

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