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  1. Home >
  2. Blog >
  3. DoS Attack After Action Report - Shell Scripts
370x370_Johannes-Ullrich.jpg
Dr. Johannes Ullrich

DoS Attack After Action Report - Shell Scripts

January 6, 2010

I wrote up a quick after action report with details about the little DoS attack that hit us. I figure that it may be handy for others to know about it.For the full report see http://isc.sans.org/presentations/jan4ddos.pdf

I mention in the report that simple shell scripts are helpful to quickly get a look at your logs while under attack. So here for the appsec streetfighters out there, some of the shell scripts I keep around to summarize my logs in a case like that:

Most recent top referrers.Defaults to last 10000 lines, but you can override that via a command line parameter.

#!/bin/sh
r=$1
if [[ $r -lt 1 ]]; then
 r=10000
fi
tail -$r access_log | cut -f4 -d'"'  \
 |  egrep -v 'http[s]?:\/\/isc[12]?\.sans\.org' \
 | grep -v 'http:\/\/www.dshield.org\/' | sort | uniq -c | sort -n

Top hosts accessing the site:

#!/bin/sh
r=$1
if [[ $r -lt 1 ]]; then
 r=10000
fi
tail -$r access_log | cut -f1 -d' ' \
    | sort | uniq -c | sort -n

The top URLs accessed on the site

#!/bin/sh
r=$1
if [[ $r -lt 1 ]]; then
r=10000
fi
tail -$r access_log | cut -f2 -d'"' \
| sort | uniq -c | sort -n

and finally, the top user agents

#!/bin/sh
r=$1
if [[ $r -lt 1 ]]; then
 r=10000
fi
tail -$r access_log | cut -f6 -d'"' | sort | uniq -c | sort -n

Nothing magic here. Just some simple functional shell scripts that have proven themselves many times before. I am using a slightly customized "combined" log format in Apache. The column numbers may differ for your install. You will have to replace 'access_log' with the file name for your log.

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United States
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United Kingdom
Spain
Belgium
Denmark
Norway
Netherlands
Australia
India
Japan
Singapore
Afghanistan
Aland Islands
Albania
Algeria
American Samoa
Andorra
Angola
Anguilla
Antarctica
Antigua and Barbuda
Argentina
Armenia
Aruba
Austria
Azerbaijan
Bahamas
Bahrain
Bangladesh
Barbados
Belarus
Belize
Benin
Bermuda
Bhutan
Bolivia
Bonaire, Sint Eustatius, and Saba
Bosnia And Herzegovina
Botswana
Bouvet Island
Brazil
British Indian Ocean Territory
Brunei Darussalam
Bulgaria
Burkina Faso
Burundi
Cambodia
Cameroon
Cape Verde
Cayman Islands
Central African Republic
Chad
Chile
China
Christmas Island
Cocos (Keeling) Islands
Colombia
Comoros
Cook Islands
Costa Rica
Croatia (Local Name: Hrvatska)
Curacao
Cyprus
Czech Republic
Democratic Republic of the Congo
Djibouti
Dominica
Dominican Republic
East Timor
East Timor
Ecuador
Egypt
El Salvador
Equatorial Guinea
Eritrea
Estonia
Ethiopia
Falkland Islands (Malvinas)
Faroe Islands
Fiji
Finland
France
French Guiana
French Polynesia
French Southern Territories
Gabon
Gambia
Georgia
Germany
Ghana
Gibraltar
Greece
Greenland
Grenada
Guadeloupe
Guam
Guatemala
Guernsey
Guinea
Guinea-Bissau
Guyana
Haiti
Heard And McDonald Islands
Honduras
Hong Kong
Hungary
Iceland
Indonesia
Iraq
Ireland
Isle of Man
Israel
Italy
Jamaica
Jersey
Jordan
Kazakhstan
Kenya
Kingdom of Saudi Arabia
Kiribati
Korea, Republic Of
Kosovo
Kuwait
Kyrgyzstan
Lao People's Democratic Republic
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Lesotho
Liberia
Liechtenstein
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Macau
Macedonia
Madagascar
Malawi
Malaysia
Maldives
Mali
Malta
Marshall Islands
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New Zealand
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Nigeria
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Papua New Guinea
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Peru
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Pitcairn
Poland
Portugal
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Qatar
Reunion
Romania
Russian Federation
Rwanda
Saint Bartholemy
Saint Kitts And Nevis
Saint Lucia
Saint Martin
Saint Vincent And The Grenadines
Samoa
San Marino
Sao Tome And Principe
Senegal
Serbia
Seychelles
Sierra Leone
Sint Maarten
Slovakia (Slovak Republic)
Slovenia
Solomon Islands
South Africa
South Georgia and the South Sandwich Islands
South Sudan
Sri Lanka
St. Helena
St. Pierre And Miquelon
Suriname
Svalbard And Jan Mayen Islands
Swaziland
Sweden
Switzerland
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