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COEN 350

COEN 350. Security Threats. Network Based Exploits. Phases of an Attack Reconnaissance Scanning Gaining Access Expanding Access Covering Tracks. Reconnaissance. Social Engineering “I cannot access my email. What do I do?” Dumpster Diving (especially useful when people move)

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COEN 350

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  1. COEN 350 Security Threats

  2. Network Based Exploits Phases of an Attack • Reconnaissance • Scanning • Gaining Access • Expanding Access • Covering Tracks

  3. Reconnaissance • Social Engineering • “I cannot access my email. What do I do?” • Dumpster Diving (especially useful when people move) • Search the Web • Sam Spade (www.samspade.org/ssw/), CyberKit, NetScanTools, ... • Search Engine • Usenet postings • Whois

  4. Reconnaissance Databases • To research .com , .net, and .org domain names:InterNIC whois feature: www.internic.net/whois.html allwhois, network soultions, ... • ARIN: American Registry for Interent Numbers (www.arin.net/whoiis/arin-whois.html) • RIPE (Europe) www.ripe.net • APNIC (Asia Pacific) www.apnic.net

  5. Scanning Once we have a target, we need to get to know it better. Methods: • War Dialing (to find out modem access) • Network Mapping • Vulnerability Scanning • War Driving

  6. Scanning: War Dialing Purpose: Find a modem connection. • Many users in a company install remote PC software such as PCAnywhere without setting the software up correctly. • War Dialer finds these numbers by going through a range of phone numbers listening for a modem. • Demon Dialer tries a brute force password attack on a found connection. • Typically: war dialing will find an unsecured connection.

  7. Scanning: Network Mapping Ping: • ping is implemented using the Internet Control Message Protocol (ICMP) Echo Request. • A receiving station answers back to the sender. • Used by system administrators to check status of machines and connections.

  8. Scanning: Network Mapping Traceroute: • Pings a system with ICMP echo requests with varying life spans (= # of hops allowed). • A system that receives a package with expired numbers of hops sends an error message back to sender. • Traceroute uses this to find the route to a given system. • Useful for System Administration

  9. Scanning: Network Mapping Cheops: Network Scanner (UNIX based) (Uses traceroute and other tools to map a network.) Cheops et Co. are the reason that firewalls intercept pings.

  10. Scanning: Port Scans • Applications on a system use ports to listen for network traffic or send it out. • 216 ports available, some for known services such as http (80), ftp, ... • Port scans send various type of IP packages to target on different ports. • Reaction tells them whether the port is open (an application listens).

  11. Scanning: Nmap • Uses different types of packets to check for open ports. • Can tell from the reaction what OS is running, including patch levels. • Can run in stealth mode, in which it is not detected by many firewalls.

  12. Gaining Access • Gain access using application and OS attacks. • Gain access using network attack.

  13. Gaining Access through Apps and OS • Stack-Based Overflow Attacks Stack is the area where function arguments and return addresses are saved. • Password Attacks • Web Application Attacks

  14. Stack Based Attacks If a function is called, then the registers are saved on the stack, followed by the arguments, followed by the return address. At the end of the function execution, the registers are restored from stack.

  15. Stack Based Attack If a function takes string arguments for inputs and is poorly written, then a long string input leads to the stack to be unwound incorrectly. As a consequence, some of the input ends up as register values. You can use this to execute short code snippets.

  16. Stack Based Attacks (How to do it?) • Take a popular application, install it on your machine, and see whether you can crash it by giving it long inputs. • If it does, use the debug function to find out what register values get loaded. Any debugger installed on your system will tell you. • Fine-tune the input to let you do something interesting • Ready to go and wreck havoc.

  17. Buffer Attack Example • On a Unix system, use a buffer overflow in a network accessible program (running at root level) to execute: /bin/sh –c “echo 12345 stream tcp nowait root /bin/sh sh –i” >> /etc/inetd.conf; killall –HUP inetd • This shell adds a network service at port 12345 that spawns a command shell with full privileges.

  18. Web Application Attacks • The URL not only contains the web address of a site, but also input: http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=web+application+attack • A poorly written webpage allows the viewer to input data in an uncontrolled fashion. If the webpage contains SQL, the user might execute SQL commands.

  19. Gaining Access through Network Attacks: Sniffing • Sniffer: Gathers traffic from a LAN. • Examples: Snort www.snort.org, Sniffit reptile.rug.ac.be/~coder/sniffit/sniffit.html • To gain access to packages, use spoofed ARP (Address Resolution Protocol) to reroute traffic.

  20. Session Hijacking • IP Address Spoofing: Send out IP packages with false IP addresses. • If an attacker sits on a link through which traffic between two sites flows, the attacker can inject spoofed packages to “hijack the session”. • Details omitted.

  21. Exploiting and Maintaining Address After successful intrusion, an attacker should: • Use other tools to gain root or administrator privileges. • Erase traces (e.g. change log entries). • Take measures to maintain access. • Erase security holes so that no-one else can gain illicit access and do something stupid to wake up the sys. ad.

  22. Trojans • A program with an additional, evil payload. • E.g. Running MS Word also reinstalls a backdoor.

  23. Backdoors • Bypass normal security measures. Example: netcat • Install netcat on victim with the GAPING_SECURITY_HOLE option. C:\ nc -1 –p 12345 –e cmd.sh • In the future: connect to port 12345 and start typing commands.

  24. Backdoors • BO2K (Back Orifice 2000) runs in stealth mode (you cannot discover it by looking at the processes tab in the TASK MANAGER. • Otherwise, it is a remote control program like pcAnyWhere, that allows accessing a computer over the net.

  25. Backdoors • RootKit: A backdoor built as a Trojan of system executables such as ipconfig. • Kernel-Level RootKit: Changes the OS, not only system executables.

  26. Responses • Filter Internet Connections. • Run Security Audits. (E.g. try to use hacking tools to break into your own system.) • Backup all data and prepare for complete reinstall after an incident. • Log on write-only media. • For commercial sites: Develop a comprehensive security policy.

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