Network Attack & Defense: Difference between revisions

From
Jump to navigation Jump to search
No edit summary
 
(8 intermediate revisions by the same user not shown)
Line 1: Line 1:
==overview==
==network attack & defense==


* introduction
* introduction
Line 8: Line 8:
* summary
* summary
* references
* references



==introduction==
==introduction==
Line 38: Line 37:
of serious safety gaps. They maintain the internet in a half
of serious safety gaps. They maintain the internet in a half
hour to paralyze to be able.
hour to paralyze to be able.



==network attacks==
==network attacks==

'''overview'''
'''overview'''
* '''term clarifying'''
* '''term clarifying'''
Line 84: Line 81:
** using safety gaps in programs, those on the attacked computer runs (e.g. Web Browser)
** using safety gaps in programs, those on the attacked computer runs (e.g. Web Browser)
** weak passwords
** weak passwords


* more in http://www.computec.ch/dokumente/allgemein/angriffsmoeglichkeiten_auf_netzwerke/angriffsmoeglichkeiten_auf_netzwerke.pdf




Line 106: Line 106:
'''with attention of these measures is avoidable over 99% all "Hacks"!'''
'''with attention of these measures is avoidable over 99% all "Hacks"!'''


* '''network analysis'''
==network analysis==
** data security consider!
* data security consider!
** only within the own range permits!
* only within the own range permits!
** difficult with purposeful masking
* difficult with purposeful masking
** motivation:
* motivation:
*** weak points recognize:
** weak points recognize:
** missing Patches
* missing Patches
** unsatisfactory configuration
* unsatisfactory configuration
** foreigner software (Filesharing Tools, Serv u)
* foreigner software (Filesharing Tools, Serv u)
*** abuse/intruders recognize
** abuse/intruders recognize
** possibilities:
* possibilities:
*** port-scan
** port-scan
**** search for services, which are attainable over the net
*** search for services, which are attainable over the net
*** computer scan
** computer scan
**** attempt, over the net additional information about the configuration computers to
*** attempt, over the net additional information about the configuration computers to
*** network monitorings receive
** network monitorings receive
**** monitoring and analysis of connections
*** monitoring and analysis of connections



==port-scans==
==port-scans==

* in principle: each program on a computer, which is to accept connections from the outside, must open a haven before (status: Listening)
* in principle: each program on a computer, which is to accept connections from the outside, must open a haven before (status: Listening)
* open ones of haven can be recognized
* open ones of haven can be recognized
Line 146: Line 144:


==computer analysis - nessus==
==computer analysis - nessus==
* reaction of a computer when responding a port

* reaction of a computer when responding a haven
* OS finger prints
* OS finger prints
* analysis of weak points (missing Patches/unsatisfactory configuration)
* analysis of weak points (missing Patches/unsatisfactory configuration)
*with what?
* with what?




Line 172: Line 169:
** comparison to earlier results or same computer configuration verifies classification of importance possible and meaningfully
** comparison to earlier results or same computer configuration verifies classification of importance possible and meaningfully



'''Negative result does not mean that the computer is safe!'''
*'''Negative result does not mean that the computer is safe!'''


==summary==
==summary==

*'''there is no chance to be save'''
*'''there is no chance to be save'''


Line 181: Line 178:


==references==
==references==

* http://www.computec.ch/dokumente/allgemein/angriffsmoeglichkeiten_auf_netzwerke/angriffsmoeglichkeiten_auf_netzwerke.pdf
* http://www.computec.ch/dokumente/allgemein/angriffsmoeglichkeiten_auf_netzwerke/angriffsmoeglichkeiten_auf_netzwerke.pdf
* http://www.telematik-institut.de/publikationen/online-vorlesungen/weitere_vorlesungen_und_skripte/SION-kap-3.4.pdf
* http://www.telematik-institut.de/publikationen/online-vorlesungen/weitere_vorlesungen_und_skripte/SION-kap-3.4.pdf

Latest revision as of 21:31, 28 January 2005

overview

  • introduction
  • network attacks
    • overview
    • port-scans
    • nessus
  • summary
  • references

introduction

  • IBM: increases of network attacks

number of the attacks on networks of state institutions between july and august last yearly around 55 % risen

  • 80% of all network attacks are committed within the firewall

of protected range ComputerWorld, Januar 2002

historical outline

  • 1971 John Draper find out that a toy whistle from a Muesli box

reproduces exactly the clay/tone that a free voice grade channel opens

  • 1984 in the USA are discharged the Comprehensive Crime

control act, a law that more possibilities to the secret service gives to put to credit card cheats and hackers the handicraft

  • 1986 in the USA two further laws, which concern themselves

with attacks on computer systems, are adopted: The computer Fraud and electronics Communications Privacy act

  • 1988 Robert Morris bring 6.000 computers in the internet with

a virus to the crash and to a punishment of $10.000 are condemned

  • 1994, summer Vladimir Levin, graduate of the pc. Petersburg

Universit, steal with a Russian group of hackers 10 millions $ of the Citibank. He is arrested 1995 in London.

  • 1998, 19 May members of the group of hackers of L0pht warn

of serious safety gaps. They maintain the internet in a half hour to paralyze to be able.

network attacks

overview

  • term clarifying
    • the term network attack is legally problematic
    • The legal definition of an attack assumes this took place only if someone arrived into the network!


  • possible aggressors - hackers (private or professional)
    • classically
      • overcoming of entrance barriers
      • no destruction of data
      • no change of data
    • criminal (Cracker)
      • spying data
      • manipulation of data
      • destruction of data and systems


  • possible attack targets
    • everyone is endangers
    • everyone is a goal
    • nearly everyone was already a goal


  • goals of the aggressor
    • feigning a wrong identity
    • seeing confidential enterprise data
    • changing and falsifying data/messages
    • transfer of dangerous programs into the system
    • enterprises in discredit bring


  • motivation
    • tests of the own abilities and borders
    • monetary goals
    • revenge of quit coworkers


  • points of attack and weak points
    • a main cause for the multiplicity at safety problems in the InterNet represents the architecture in principle of the communication protocols TCP/IP and UDP
    • to using the ignorance of users
    • using safety gaps in programs, those on the attacked computer runs (e.g. Web Browser)
    • weak passwords



  • what can we do?
    • own systems and of them (normal) behavior (very much) good know!
    • on remarkablenesses concentrate, e.g.:
      • computer is unexpectedly slow
      • non removable disk is the being obvious for unexplainable reasons fully
      • first examines
    • calm remains; Panic causes errors
    • be prepared!
    • do allways
      • uninstall
      • switching off
      • configuring
      • patching
      • virus protection
      • user behaviors:
        • optimal: users do not install software
        • for minimum requirement: training of the users: software from the internet saves risks

with attention of these measures is avoidable over 99% all "Hacks"!

network analysis

  • data security consider!
  • only within the own range permits!
  • difficult with purposeful masking
  • motivation:
    • weak points recognize:
  • missing Patches
  • unsatisfactory configuration
  • foreigner software (Filesharing Tools, Serv u)
    • abuse/intruders recognize
  • possibilities:
    • port-scan
      • search for services, which are attainable over the net
    • computer scan
      • attempt, over the net additional information about the configuration computers to
    • network monitorings receive
      • monitoring and analysis of connections

port-scans

  • in principle: each program on a computer, which is to accept connections from the outside, must open a haven before (status: Listening)
  • open ones of haven can be recognized
  • which be attainable should, are also visibly
  • problem: Some haven under certain conditions are only activated
  • which haven? (purposefully at particulars of haven, "waving Known" haven, haven rank (theoretical 1-65535))
  • with what?
    • freeware haven scanner: NMAP http://www.nmap.org
    • recognizing the haven status
    • the behavior of the computer on detailed packages depends on the operating system, IP stack and the applications


  • OS finger print (result can supply reference)
  • Suspekte computer locally to examine
    • opened port lists
    • which process keeps which haven open?
    • interesting are doubtful haven with status "LISTENING"
  • local analysis potentially compromised computer

computer analysis - nessus

  • reaction of a computer when responding a port
  • OS finger prints
  • analysis of weak points (missing Patches/unsatisfactory configuration)
  • with what?


  • freeware scanner NESSUS (http://www.nessus.org)
    • two-piece:
      • server ("Daemon") on Unix
      • Client on Unix or Windows 32
  • NESSUS be based on Nmap, has however additional functions
    • scanning on safety gaps
    • contains many prefabricated "Plugins"
    • script language for supplementing own Plugins
    • NESSUS scans not only the system to open ports, it tries also, dependent on the selected scanmethod, to recognize existing weak points of the individual server services
    • with the option "intensively" attacks on the target computer are implemented, which can lead also to system crashes


  • evaluation of the Nessus results:
    • doubtful
    • knowledge about scanned computers is necessary
    • often false alarm, results
    • results can be stored in data base
    • comparison to earlier results or same computer configuration verifies classification of importance possible and meaningfully


  • Negative result does not mean that the computer is safe!

summary

  • there is no chance to be save
  • but you can be close to

references