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Bug #5076

open

keyword content does not work over reassembled TCP

Added by Philippe Antoine over 2 years ago. Updated 12 months ago.

Status:
New
Priority:
Normal
Assignee:
Target version:
Affected Versions:
Effort:
Difficulty:
Label:

Description

Using rule
alert ip any any -> any any (content:"HTTP/2.loc"; sid:11;)

on attached pcap

with stream.reassembly.toserver-chunk-size=25

does not trigger an alert

It does trigger the alert without the setting.

I fear we might have an evasion if I split the packets over the default value of 2560...


Subtasks 2 (0 open2 closed)

Bug #5110: keyword content does not work over reassembled TCP (6.0.x backport)RejectedVictor JulienActions
Bug #5111: keyword content does not work over reassembled TCP (5.0.x backport)RejectedActions

Related issues 2 (2 open0 closed)

Related to Suricata - Documentation #2470: document content inspection in chunksFeedbackEric UrbanActions
Related to Suricata - Task #4431: libsuricata: Example showing libsuricata as a replacement for libnids (network grep)In ReviewPhilippe AntoineActions
Actions #2

Updated by Philippe Antoine over 2 years ago

This was found during investigation of #4858

Actions #5

Updated by Jeff Lucovsky over 2 years ago

  • Copied to Bug #5110: keyword content does not work over reassembled TCP (6.0.x backport) added
Actions #6

Updated by Jeff Lucovsky over 2 years ago

  • Copied to Bug #5111: keyword content does not work over reassembled TCP (5.0.x backport) added
Actions #7

Updated by Philippe Antoine almost 2 years ago

From talk with Victor, this is a known limitation, where the chunk size is supposed to be a bit random to protect against evasion attempts.

The solution may be to use hyperscan as a streaming engine (instead of running it on different chunks/blocks)

Actions #8

Updated by Victor Julien almost 2 years ago

  • Label deleted (Needs backport)
Actions #9

Updated by Philippe Antoine almost 2 years ago

Actions #10

Updated by Victor Julien over 1 year ago

  • Target version changed from 7.0.0-beta1 to 8.0.0-beta1
Actions #11

Updated by Philippe Antoine over 1 year ago

  • Related to Task #4431: libsuricata: Example showing libsuricata as a replacement for libnids (network grep) added
Actions

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