Add JA3S fingerprint support #3874
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Generate JA3S fingerprints based on fields in the ServerHello record.
Add JA3S object to TLS JSON logger (extended log).
Add Ja3SGetHash() to return the content of the JA3S hash buffer from
the TLS session.
Example:
function init (args)
local needs = {}
needs["protocol"] = "tls"
return needs
end
function setup (args)
filename = SCLogPath() .. "/ja3s_hash.log"
file = assert(io.open(filename, "a"))
end
function log (args)
ja3s_hash = Ja3SGetHash()
if ja3s_hash == nil then
return
end
file:write(ja3s_hash .. "\n")
file:flush()
end
function deinit (args)
file:close()
end
In the example above, each JA3S hash is logged to a log file.
Add Ja3SGetString() to return the content of the JA3S string buffer from
the TLS session.
Example:
function init (args)
local needs = {}
needs["protocol"] = "tls"
return needs
end
function setup (args)
filename = SCLogPath() .. "/ja3s_string.log"
file = assert(io.open(filename, "a"))
end
function log (args)
ja3s_string = Ja3SGetString()
if ja3s_string == nil then
return
end
file:write(ja3s_string .. "\n")
file:flush()
end
function deinit (args)
file:close()
end
Match on JA3S hash using ja3s.hash keyword, e.g:
alert tls any any -> any any (msg:"ja3s.hash test";
ja3s.hash; content:"b26c652e0a402a24b5ca2a660e84f9d5"; sid:1;)
Match on JA3S string using ja3s.string keyword, e.g:
alert tls any any -> any any (msg:"ja3s.string test";
ja3s.string; content:"10-11-12"; sid:1;)
This was referenced May 20, 2019
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This pull request implements JA3S fingerprints as implemented in the bro script in the JA3 github repo:
https://github.com/salesforce/ja3/blob/master/bro/ja3s.bro
Updates:
Redmine:
https://redmine.openinfosecfoundation.org/issues/2684