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Wireshark twoo twooo two twoo...
Can you find the flag? shark2.pcapng.
- 1.Upon initial inspection, there seem to be a lot of requests to a
/flagendpoint. Each request shows a different flag so these must be a distraction. - 2.After searching through the file I noticed many DNS requests for various subdomains of
reddshrimpandherring.com. This looks like the suspicious traffic that one of the challenge hints refers to. - 3.A lot of the DNS queries have a destination of 8.8.8.8. However, a subset have a destination for 18.217.1.57.
- 4.We can apply the filter
dns and ip.dst==18.217.1.57to only see DNS requests to this IP address. If we take the subdomains ofreddshrimpandherring.comand append them in order we get:cGljb0NURntkbnNfM3hmMWxfZnR3X2RlYWRiZWVmfQ== - 5.Decoding the above string as base64 gives us the flag.
- 6.Alternatively, this file can be analyzed using apackets.com. Just upload the file, go to the DNS page, and scroll down to see the requests neatly organized.
picoCTF{dns_3xf1l_ftw_deadbeef}