Snort mailing list archives

Re: ShodanHQ Rule


From: Joel Esler <jesler () sourcefire com>
Date: Tue, 22 Oct 2013 17:07:55 -0400

Geoff,

I’m confused about what you are trying to detect.  Are you trying to detect Shodan indexing the services on your 
network?  Is that the intent of the rule?


On Oct 22, 2013, at 4:50 PM, Geoff Serrao <geoff.serrao () gmail com> wrote:

While browsing Shodanhq.com I wondered if shodan sent along the http "Referer" header when clicking on search result 
links. 

Sure enough, shodan passes along the http referer with the client request: 

Referer: http://www.shodanhq.com/search?q=vulnerable-software

Shodanhq only indexes services listening on the following ports, so only dest port 80 is necessary. 

HTTP (80) FTP (21) SSH (22) SNMP (161) SIP (5060) 

alert tcp $EXTERNAL_NET any -> $HOME_NET 80 (msg:"RECON HTTP Request with ShodanHQ.com/search?q= in HTTP Referer 
header."; \
flow:established, to_server; \
content:"Referer: http://www.shodanhq.com/search?q=";, http_header; \
reference: url, http://www.shodanhq.com/search?q=vulnerable-software; classtype: attempted-recon;)

I don't know how practical this rule is, but It would be interesting to see if any sysadmins were to implement this 
rule and learn if they are listed somewhere on shodan.

Pages increment like this: http://www.shodanhq.com/search?q=linksys&page=2 so we should be good with that content 
match.
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Free Intel webinars can help you accelerate application performance.
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the latest Intel processors and coprocessors. See abstracts and register >
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