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Feature #4660

open

base64_decode cannot used with Transformations like pcrexform

Added by albert wang over 2 years ago. Updated 9 months ago.

Status:
New
Priority:
Normal
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Target version:
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Description

I want to extract the regular matching content and then base64 decode it.

alert http any any -> any any (msg:"test";flow:from_client,established;http.request_body;pcrexform:"#(\w{8})#";base64_decode:bytes 4,offset 0 ;base64_data;conten:"test";

But,it reported a erro : previous transforms not consumed (list: 2, transform_cnt 1)

I found the reason,This is because base64_decode cannot be used with Transformations like pcrexform;
So I can only add pcre:"/./"; before base64_decode . But this pcre:"/./"; is meaningless.

alert http any any -> any any (msg:"test";flow:from_client,established;http.request_body;pcrexform:"#(\w{8})#";pcre:"/./";base64_decode:bytes 4,offset 0 ;base64_data;conten:"test";

Actions #1

Updated by Philippe Antoine 9 months ago

  • Tracker changed from Optimization to Feature
  • Assignee set to OISF Dev
  • Target version set to 8.0.0-beta1

As I understand, a solution could be a transform that is base64_decoding (instead of a keyword)

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