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Bug #2098

closed

isdataat: fix parsing issue with leading spaces

Added by Harley H about 7 years ago. Updated about 7 years ago.

Status:
Closed
Priority:
Normal
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Target version:
Affected Versions:
Effort:
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Description

Hello,
I'm noticing a potential issue with a negated isdataat check. I'm testing the following four rules against the pcap linked below:

alert tcp any any -> any any (msg: "It's Alive!!!"; content: "Here"; isdataat: !114; sid: 1102010; rev: 1;)
alert tcp any any -> any any (msg: "It's Alive!!!"; content: "Here"; isdataat: 114; sid: 1102011; rev: 1;)
alert tcp any any -> any any (msg: "It's Alive!!!"; content: "Here"; isdataat: !113; sid: 1102012; rev: 1;)
alert tcp any any -> any any (msg: "It's Alive!!!"; content: "Here"; isdataat: 113; sid: 1102013; rev: 1;)

The packet simply contains the following 114 byte string:
"Here is a 114 byte packet to test how a negated isdataat checks works in Suricata. Seems something may be amiss..."

I'd expect rules 1102010 and 1102013 to alert, and that is what happens in Snort. In Suricata, only 1102012 and 1102013 cause an alert. I'm using Suricata 3.2.1.


Files

test.pcap (740 Bytes) test.pcap Harley H, 04/20/2017 10:43 AM
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