Questions tagged [snort]

Snort is an open source network intrusion detection and prevention system (NIDS/NIPS).

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31 views

How do I get snort to detect traffic going to metasploitable docker container? [closed]

I have setup Snort and I have Metasploitable 2 running in a docker container on Centos 7 host. I am trying to get Snort to detect traffic traveling to the Metasploitable 2 container. I've tried ...
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31 views

need help using PCRE in snort

Can someone guide me how to write PCRE option to match list of websites such as for eg facebook.com, google.com,ebay.com? I tried to understand from manual but couldn't get is right? regards,
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28 views

using dsize:<500 parameter in snort

I am tring to make rule to alert when downloading jpg file less than certain size . i used parameter dsize:<500; But it is not alerting when i tried to run pcap file containing jpg less than 500MB. ...
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59 views

Snort automatic protocol detection

Does Snort have the "automatic protocol detection" function like Suricata? I read that Snort 3 has "Autodetect services for portless configuration" feature. Does it mean that this ...
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2answers
824 views

Difference between Zeek (Bro) and Snort 3

I'm trying to find difference between Zeek and Snort 3. Сan anybody tell me what are the advantages of Zeek against Snort 3?
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33 views

Snort analyze reply based on request

I'm trying to write a snort rule which detects if certain binary files where requested via HTTP based on a regex rule matching there names. But it should only send an alert if the file exists (e.g. ...
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1answer
56 views

ids - How do I match any string in a list of snort contents?

If I do something like alert tcp any any <> any any (content:"TestA"; content:"TestB"; sid:1000000; msg:"Syntax correct!";) then the syntax is correct, but, what I would like to do is to ...
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50 views

Trying to use SNORT to alert all non-http traffic on port 80

I am using Snort 2 and I can't find anything that will specifically rule out the HTTP traffic so that I can alert for any other traffic coming in (or out) on port 80.
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43 views

Is there an easy Snort rule to CVE mapping database somewhere?

I feel like should be an easy way to map between SNORT rules and associated CVEs. I'm aware of their own search function on their site at: https://www.snort.org/rule-docs, but I feel like it's giving ...
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103 views

Snort Content first 3 bytes the same then create an alert [closed]

I was wondering if you could add into a snort rule the ability to only alert if the first 3 bytes match. I think I need to edit the content in my current rule content:"|37 e1 a4|"; I can add the full ...
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1answer
368 views

How to create content rule in Snort

The aim is to detect, if anyone in the HOME_NET is searching for a particular term - say "terrorism" and generate an alert via a content based rule. I am using Snort 2.9 installed in a virtual ...
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109 views

error read-file in snort when reading back pcap file

I get this error when using snort -r to read a saved pcap file and apply snort rules on it. ERROR : pfring daq does not support read-file I am running snort in Security Onion I tried many things: ...
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1answer
295 views

Explain this snort rule [closed]

Please explain the following Snort rule. Describe the meanings of all the options and modifiers used in the rule alert tcp $EXTERNAL_NET any -> $SQL_SERVERS 1433 (msg:"Attack Detected"; flow:...
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68 views

Snort rules to detect metasploit's trojan [duplicate]

I'm currently working on Snort and I'm trying to detect meterpreter sessions in reverse TCP or HTTPS, a Trojan ... Does anyone know snort rules in order to detect this? Despite my research, I found ...
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1answer
459 views

Can Snort inline/blocking mode block traffic from one host to another on internal LAN?

I'm putting Snort on a wifi router. My understanding is when in inline/blocking mode, I have to bridge a LAN interface to the WAN interface for packet inspection. If this is the case, it does not seem ...
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207 views

Stateful detection in Snort

From whatever I have read of Snort, it can analyse a single packet at a time and raise an alert based on its rules. What if I wish to have a rule based on multiple packets such as analysis of a ...
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1answer
62 views

Confusion Matrix for Generated Signatures in Snort

How do we come with True Positives and False Negatives rates when creating signatures in IDS? How do we measure the signatures efficiency? I've seen so many papers that discuss the same, but how do ...
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265 views

OpenAppID with Snort on pfSense [closed]

I'm using OpenAppID with Snort on pfSense, it actually work but when I view some script detector, it just detect by http pattern, which I can replace by using snort rule (with "content" option). So ...
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3k views

Snort rule for syn flood attacks - Limiting number of alerts

So I have a snort rule that detects syn flood attacks that looks like this: alert tcp any any -> $HOME_NET 80 (msg:”SYN Flood - SSH"; flags:S; flow: stateless; detection_filter: track by_dst, ...
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2answers
557 views

How to analyze .pcap file to write a generic snort rule to detect c&c activity

I am diving into snort and trying to figure out what everything does but I'm having a little trouble. I have a .pcap file I want to analyse and I know there is malicious c&c traffic on it. (...
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1answer
270 views

Is there a way to change the format of the output from snort?

I'm pretty new to snort and don't know too much about it. I am trying to put together a report of my snort files but, I only want the connections not the entire flows. For example, say I have a few ...
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2answers
5k views

Create a snort rule that will alert on traffic on ports 443 & 447

Using the learning platform, the subject is snort rules. Question is: Create a snort rule that will alert on traffic with destination ports 443 and 447. My attempts: alert tcp any any -> ...
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675 views

How to determine TLS traffic in snort signature

I am trying to have a snort signature that can detect encrypted traffic but I am not able to determine the TLS traffic using a snort signature. The content keyword search in the payload of the packet,...
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1answer
448 views

Are these snort alerts false positives or attacks?

Can anyone describe this alert please? I am confused if an attack is run against my network or not. I run snort IDS/IPS through a pfsense firewall.
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160 views

In Snort for Windows, how do I limit log file size, keep that file, and make another file instance

I have Snort for Windows. I am trying to make a log file of say size limit 1MB. When the log file hits the 1MB maximum, I want it to close that file (snort.log.1234567890) and open a new log file ...
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3answers
3k views

Threshold for DDOS Attack

I am trying to understand and simulate SYN Flood DDOS attacks. I am using snort to give me alerts. While I have control over the rate for my testing, I am interested in knowing what a good estimate of ...
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1answer
841 views

How to sniff VPN traffic using Snort?

Here's what I want to do: I want to use a VPN client on my PC (like TunnelBear). Then I want to use Snort to sniff traffic before it's encrypted and after it's decrypted by VPN. So basically I want ...
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1answer
551 views

Loopback with Suricata

Is there any way of analyzing loopback traffic with Suricata? I am trying it this way without success: root@security-onion:/home/sar/TFM/alerts/suricata# suricata -c /etc/suricata/suricata.yaml -i ...
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1answer
567 views

Analyzing Apache log with Snort

I need to analyze an Apache log with Snort and others IDS/WAFs (Suricata, mod_security and Shadow Daemon). In order to do so, I was thinking about create TCP packets with the GET and POST requests ...
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382 views

Are these Snort rules correct?

I wrote this rule so that when there are more than three failed SSH connection attempts that there is an alert but it is not working. Are these rules badly written? Or if not I ask the exact writing ...
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186 views

Snort not working with IDSWakeup

I have setup Snort with the registered user rules installed. I tested first by making the following rule in local.rules: alert icmp any any -> $HOME_NET any (msg:"ICMP test"; sid:10000001; rev:...
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598 views

How can I get Suricata to alert on 1 packet every time

I am trying to write a Suricata signature for testing purposes to alert every time it is triggered with a single PCAP file containing a single packet, but this is proving to be harder than I thought. ...
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1k views

Benefit of using two network interfaces for intrusion detection system

What is the benefit of using two network interfaces (management interface and sniffing interface) for an IDS such as Snort? I have used a Snort IDS where it only used one network interface for both ...
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2answers
736 views

how to write a snort rule to alert traffic that does not find any matched rules

Snort in IDS mode: If there is some traffic that does NOT find any matched rule against all existing Snort rules, how would you write a bottom rule to alert this traffic?
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1answer
588 views

pcap files for simulated attacks on SCADA systems?

I need to get hold of some pcap files belonging to a simulated attack on SCADA systems. My goal is to then use Snort for the detection. Or if somebody can suggest a practical environment to create my ...
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826 views

Snort.log output as unreadable symbols

I have recently installed Snort IDS on Linux Ubuntu 16.04LTS (not server), after experimenting and testing configuration in VitualBox. After installing and successfully validating the configuration ...
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1answer
385 views

How do I map the information in snort u2spewfoo output to the rule which triggered the alert?

I have a snort log file in unified2 format and I am able to view the output using the u2spewfoo utility. I think that I understand the generator id, signature id, and revision tell me why the alert ...
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2answers
1k views

Snort Exercises

I am beginning to study Snort rules and the teacher give to us the next exercises: A server on which Snort is installed is monitoring all traffic on subnet 172.16.0.0 with mask 255.255.0.0. From now ...
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153 views

snort add more data in alert file

I want to add more data to alert file rightnow the data what our analyst team see is very minimal and we are not giving access to them to our snort backend server, our design is like centos /var/log/...
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4k views

Snort priority range

What is the range of values for the 'priority' parameter in a Snort rule? The documentation it doesn't make it clear: The priority tag assigns a severity level to rules. A classtype rule assigns a ...
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1answer
485 views

Security Onion VMWare + OpenWRT IPTables Mirroring

I'm trying to set up SO in my home network to lab and see if I can monitor all ingress/egress traffic from my SOHO router. I don't have a switch with SPAN ports, or a network tap so I'm using OpenWRT ...
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1answer
2k views

How to detect a string in HTML with Snort?

I am trying to detect a string in HTML (already unzipped) with Snort. I set this rule to find content 7038685658 in my Apache web server's HTML: alert tcp any any <> any any (msg:"cell"; ...
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1answer
3k views

IDS Snort rule to catch Slow-Loris

I'm trying to write a rule to catch a Slow-Loris attack, this is what i have - alert tcp any any -> any any (msg:"Possible Slow Loris attack"; classtype: denial-of-service; flow: to_server, ...
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1answer
627 views

Suricata does not detect “self” traffic

I have built two simple rules alert tcp any any -> any any (msg: "tcp detected"; sid: 2; rev: 1;) alert udp any any -> any any (msg: "udp detected"; sid: 1; rev: 1;) Then from the same machine ...
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2answers
335 views

Can dual NIC Snort machine cause threats to bypass firewall?

I am thinking about building a Linux Snort machine that can listen to both WAN and LAN traffic. Setup I am thinking about: Snort computer with two NICs One NIC connected to hub/tap outside firewall (...
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160 views

snort file_inspect signature working inconsistently [closed]

I am trying snorts file inspect preprocessor for blocking incoming files from their sha256sums. I am using snort version 2.9.9.0 with daq nfq inline mode any my file_inspect preprocessor configs are ...
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1answer
680 views

Snort: Cannot decode data link type 127 reading a pcapng file

I've captured on my wifi some days ago and now I want snort to analyse the capture to detect any problem. However, when I run snort -l ./snort-log -b -c /etc/snort/snort.conf -r captura-analisar....
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2answers
196 views

How to detect long lived SSH sessioned

I am trying to figure out a way to detect ssh sessions that have been established over a long period of time. I seem to recall that there were ways to detect tcp connections that have been connected ...
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2answers
3k views

Major differences between Snort and Snort 3.0

When I visited the the Snort's website to download the source code for compilation, I found there were 2 downloads available. One was titled Snort and another was titled Snort 3.0 Has the ...
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2answers
664 views

REJECT Nikto Scans With Snort Rules

Hoping someone on here knows a way to reject Nikto traffic with Snort rules. I've been having zero luck for days finding this anywhere online. Thanks. Peace.