custom snort signature add the pattern if the context operator is not found

[Mohammed_Yasin]

creating a custom snort signature on Palo alto Firewall but didn’t found the concern context operator for match pattern.

Shall we create a context operator or how it can add the pattern if the context operator is not available?

For example:

alert tcp $HOME_NET any -> $EXTERNAL_NET 443 (msg:"[CIS] Emotet C2 Traffic Using Form Data to Send Passwords"; content:"POST"; http_method; content:"Content-Type|3a 20|multipart/form-data|3b 20|boundary="; http_header; fast_pattern; content:"Content-Disposition|3a 20|form-data|3b 20|name=|22|"; http_client_body; content:!"------WebKitFormBoundary"; http_client_body; content:!"Cookie|3a|"; pcre:"/:?(chrome|firefox|safari|opera|ie|edge) passwords/i"; reference:url,cofense.com/flash-bulletin-emotet-epoch-1-changes-c2-communication/; sid:1; rev:2;)

Not available

http_method

http_client_body

[OtakarKlier]

Hello,

Writing custom signatures is something I always leave to the vendors, its their job :). If you setup your PAN with the everything turned on, anti-virus, spyware, url filtering, dns sinkhole, using secure dns (even if it snot PAN's), SSL Decrypt, wildfire, tight policies, I think you will find not much if anything can get through. Also enable the telemetry to be sent to PAN, it helps hem write signatures for everyone :), a small way to give back.

Also use best practices on the rest of the network as well as endpoints (AV etc). 

You can always use their threat db to search and see if they already have something. If they dont put in a TAC request and they'll work on one.

https://threatvault.paloaltonetworks.com/

Regards,

[leonblum · Accepted solution]

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@OtakarKlier wrote:

Hello, 8 ball pool

Writing custom signatures is something I always leave to the vendors, its their job :). If you setup your PAN with the everything turned on, anti-virus, spyware, url filtering, dns sinkhole, using secure dns (even if it snot PAN's), SSL Decrypt, wildfire, tight policies, I think you will find not much if anything can get through. Also enable the telemetry to be sent to PAN, it helps hem write signatures for everyone :), a small way to give back.

Also use best practices on the rest of the network as well as endpoints (AV etc). 

You can always use their threat db to search and see if they already have something. If they dont put in a TAC request and they'll work on one.

https://threatvault.paloaltonetworks.com/

Regards,

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Thank you very much!! Very useful advice

[CCACieszkowski]

Hi @Mohammed_Yasin,

http_method in the Custom Vulnerability Object is the http-method Qualifier and the http_client_body is the http-req-message-body Context, i.e.,:

Albert