Differences

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--- script:x509_ext_c2 [2018/02/08 23:57] – [The Full Text Search FTS Document] veera
+++ script:x509_ext_c2 [2018/02/09 00:00] – [Detecting covert channels in X.509 Digital Certificates using the Trisul LUA API] veera
@@ Line 5: / Line 5: @@
 In this technique the covert channel is built by stuffing chunks of data into  X.509 Certificate Extensions, in this case the "Subject Key Identifier" aka SKI extension. This is usually a hash of 20 bytes.  However this is not used in certificate validation and it appears current commercial network defenses are not checking if this contains a valid value.  The C2 POC uses a large number of certificates with SKI values of 10,000 bytes !
-Detecting this is quite easy with Trisul as well as Bro IDS. This post highlights the different approaches taken.
+Detecting this is quite easy with [[https://trisul.org/docs/lua|Trisul]] as well as [[https://www.bro.org/|Bro IDS]]. This post highlights the Trisul approach.
-===== The Full Text Search FTS Document =====
+===== Trisul vs Bro approaches to the same problem  =====
 Trisul extracts metadata from network traffic and makes them available to LUA Scripts. There are two //streams// your scripts can plug into.
-  - the **Resource** stream:  these are shorter summaries of the meta data. For example the DNS Resources would be one line summary of question and answers
+  - the **Resource** stream:  these are shorter summaries of the meta data. For example the DNS Resources would be one line summary of question and answers. SSL Resources contain the DER format certificate chain.
   - the **FTS** stream: a complete text dump of the meta data. For example : The DNS FTS stream would contain documents with a full dump of all DNS fields - much like the DIG format. Similarly for SSL Certificates, the FTS stream passes text documents that mirror the `openssl x509` command.