Difference between revisions of "SNORT-RULES: Coba Menulis Rules untuk pemula"

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==Phatbot Analysis==
 
==Phatbot Analysis==
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Read the analysis of the phatbot (sometimes referred to as polybot) Trojan at
 
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http://www.lurhq.com/phatbot.html.
 
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Question 3. As with question 2, evaluate the snort signatures contained in the above document.
 
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Comment on the effectiveness of these signatures.
 
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Question 4. The waste protocol used in the phatbot Trojan originally included the capability of
 
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encrypting the peer-to-peer data stream. What effect would this have on the effectiveness of the
 
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above signature.
 
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Question 5. Do some additional research about the phatbot/polybot Trojan. Assume that phatbot
 
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develops the capability of encrypting the data stream. Phatbot has a consistent and obvious
 
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signature of network activity across multiple packets that allow it to be detected even with out
 
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access to content of the data stream. The signature may traverse multiple packets. Snort rules
 
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generally deal with packet-by-packet data signatures. This question is intentionally vague and is
 
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designed to have you apply some of the skills you have acquired to tackling a real world problem
 
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such as being able to detect malicious activity even when you do not have access to the content
 
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of the data streams. Explain in a few paragraphs what other tools and techniques you may use to
 
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detect this signature. Provide enough detail so that a campus network administrator could follow
 
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your explanation to deploy your system in production.
 
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Question 6. What techniques would you use to minimize the number of false positives with your
 
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technique described above.
 
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4
 
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Evaluation
 
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Question 7: How hard was this lab? Was it fair? How would you change it to improve it?
 
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Coba iseng-iseng baca analisa tentang phatbot / polybot trojan di  http://www.lurhq.com/phatbot.html. Coba buat rule nya.
  
 
==Referensi==
 
==Referensi==
  
 
* courses.umass.edu/cs415/labs/lab2/415-lab2-Snort.pdf
 
* courses.umass.edu/cs415/labs/lab2/415-lab2-Snort.pdf

Revision as of 10:32, 31 March 2017

Sumber: courses.umass.edu/cs415/labs/lab2/415-lab2-Snort.pdf


Snort mirip dengan tcpdump, tetapi memiliki output yang lebih bersih dan bahasa aturan yang lebih fleksibel. Sama seperti tcpdump, snort akan mendengarkan antarmuka tertentu, atau membaca jejak paket dari sebuah file. Umumnya administrator keamanan diminta untuk melihat jejak paket untuk menganalisis serangan yang terjadi. Disini kita akan belajar bagaimana menggunakan snort untuk membaca jejak dan belajar bagaimana menulis aturan / rules baru.


Alat

  • server dengan snort yang di instalasi


Bacaan

Beberapa perintah bermanfaat

Melihat perintah snort 

snort –help

Contoh membaca log 

snort –r /tmp/snort-ids-lab.log -P 5000 –c /tmp/rules –e –X -v

Versi snort yang baru punya masalah saat membaca checksum paket yang tidak benar. Kita perlu menambahkan kalimat 

config checksum_mode : none

di bagian atas rules file jika kita memperoleh checksum problem.

Tujuan utama snort adalah untuk memberikan alert administrator jika ada rules yang cocok dengan paket yang masuk. Setiap rules biasanya satu kalimat mengikuti format yang sama, seperti contoh berikut, 

alert tcp any any -> 192.168.0.100 23 (msg: "Ada yang telnet ke mesin!"; sid:1000001)

arti dari rule di atas adalah,

  • action: kasi tanda bahaya ("alert")
  • semua paket ke telnet port (port 23)
  • ke mesin 192.168.0.100
  • tambahkan string yang bisa di baca admin "Ada yang telnet ke mesin!"
  • sid - rule ID start dari 1000000

Secara umum, semua rules mengikuti aturan: 

action protocol address port direction address port (rule option)

Pada contoh,

  • Pilihan action adalah "log" atau "alert". "alert" akan menuliskan semua alert ke sebuah file "alert" yang sama. Sementara log akan menyimpan traffic untuk masing-masing IP address yang bermasalah pada sebuah folder untuk di analisa lebih lanjut.
  • Bagian protocol harus di isi "tcp", "udp",or "icmp". "Any" tidak di ijinkan.
  • Address dapat berupa notasi CIDR
  • Port dapat menggunakan range dan operator "!. Contoh log paket ke sekumpulan mesin dengan port tidak antara 6000-6010
log tcp any any -> 192.168.1.0/24 !6000:6010
  • Operator arah "->" atau "<-" atau "<>" untuk traffic bi-directional antara dua address.

Rule option dapat menentukan task yang harus dilakukan jika address dan protocol cocok. Contoh, snort rule untuk menangkap semua ICMP echo message, 

alert tcp any any -> 192.168.10.2 any (itype: 8; msg: "ping detected";)

perhatikan mengapa itype = 8?

Catatan rule option:

  • harus berada dalam kurung ( )
  • harus di akhiri dengan ;
  • Opsi yang menarik untuk di explorasi "content", "flags", dan ipoption".


Contoh Rule

alert tcp $HOME_NET 23 -> $EXTERNAL_NET any (msg:"TELNET login incorrect";
content:"Login incorrect"; flags: A+; reference:arachnids,127;)

alert udp $EXTERNAL_NET any -> $HOME_NET 53 (msg:"EXPLOIT BIND Tsig
Overflow Attempt"; content:"|80 00 07 00 00 00 00 00 01 3F 00 01 02|/bin/sh";)

alert tcp $EXTERNAL_NET any -> $HOME_NET any (msg:"SCAN FIN"; flags: F;
reference:arachnids,27;)

alert tcp $EXTERNAL_NET any -> $HOME_NET 23 (msg:"MISC linux rootkit attempt
lrkr0x";flags: A+; content:"lrkr0x";)5. alert tcp $EXTERNAL_NET any -> $HTTP_SERVERS 80 (msg:"WEB-CGI view-source
access ";flags: A+; content:"/view-source?../../../../../../../etc/passwd";
nocase;reference:cve,CVE-1999-0174;)

alert icmp any any -> any any (msg:"ICMP Source Quench"; itype: 4; icode: 0;)

alert tcp $EXTERNAL_NET any -> $HOME_NET 53 (msg:"DNS EXPLOIT named
overflow";flags:
A+;content:"thisissometempspaceforthesockinaddrinyeahyeahiknowthisislamebutanyway
whocareshorizongotitworkingsoalliscool"; reference:cve,CVE-1999-0833;)

alert tcp $EXTERNAL_NET any -> $HOME_NET 139 (msg:"NETBIOS SMB
ADMIN$access"; flow:to_server,established; content:"\\ADMIN$|00 41 3a 00|";
reference:arachnids,340; classtype:attempted-admin; sid:532; rev:4;)

alert ip $EXTERNAL_NET $SHELLCODE_PORTS -> $HOME_NET any
(msg:"SHELLCODE sparc NOOP"; content:"|a61c c013 a61c c013 a61c c013 a61c
c013|"; reference:arachnids,355; classtype:shellcode-detect; sid:646; rev:4;)

Phatbot Analysis

Coba iseng-iseng baca analisa tentang phatbot / polybot trojan di http://www.lurhq.com/phatbot.html. Coba buat rule nya.

Referensi

  • courses.umass.edu/cs415/labs/lab2/415-lab2-Snort.pdf
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