Security Chapter 9 Copyright 2004 Prentice-Hall Panko’s Business Data Networks and Telecommunications, 5th edition
Trends in Computer and Network Security
Figure 9-1: CSI/FBI Survey Survey conducted by the Computer Security Institute (www.gocsi.com). Based on replies from 530 U.S. Computer Security Professionals. If fewer than twenty firms reported quantified dollar losses, data for the threat are not shown.
Figure 9-1: CSI/FBI Survey Had at Least One Security Incident in This Category (May Have Had Several) Percent Reporting an Incident in 1997 Percent Reporting an Incident in 2003 Number Reporting Quantified Losses in 2003 Average Reported Annual Loss Per Firm (1000s) in 1997 Average Reported Annual Loss Per Firm (1000s) in 2003 Viruses 82% 82% 254 $76 $200 Insider Abuse of Net Access Not Asked 80% 180 Not Asked $136
Figure 9-1: CSI/FBI Survey Had at Least One Security Incident in This Category (May Have Had Several) Percent Reporting an Incident in 1997 Percent Reporting an Incident in 2003 Number Reporting Quantified Losses in 2003 Average Reported Annual Loss Per Firm (1000s) in 1997 Average Reported Annual Loss Per Firm (1000s) in 2003 Laptop Theft 58% 59% 250 $38 $47 Unauthorized Access by Insiders 40% 45% 72 Not Asked $31
Figure 9-1: CSI/FBI Survey Had at Least One Security Incident in This Category (May Have Had Several) Percent Reporting an Incident in 1997 Percent Reporting an Incident in 2003 Number Reporting Quantified Losses in 2003 Average Reported Annual Loss Per Firm (1000s) in 1997 Average Reported Annual Loss Per Firm (1000s) in 2003 Denial of Service 24% 42% 111 $77 $1,427 System Penetration 20% 36% 88 $132 $56 Sabotage 14% 21% 61 $164 $215
Figure 9-1: CSI/FBI Survey Had at Least One Security Incident in This Category (May Have Had Several) Percent Reporting an Incident in 1997 Percent Reporting an Incident in 2003 Number Reporting Quantified Losses in 2003 Average Reported Annual Loss Per Firm (1000s) in 1997 Average Reported Annual Loss Per Firm (1000s) in 2003 Theft of Proprietary Information 20% 21% 61 $954 $2,700 Financial Fraud 12% 15% 61 $958 $329
Figure 9-1: CSI/FBI Survey Had at Least One Security Incident in This Category (May Have Had Several) Percent Reporting an Incident in 1997 Percent Reporting an Incident in 2003 Number Reporting Quantified Losses in 2003 Average Reported Annual Loss Per Firm (1000s) in 1997 Average Reported Annual Loss Per Firm (1000s) in 2003 Telecom Fraud 27% 10% 34 Not Asked $50 Telecom Eavesdropping 11% 6% Not Asked Not Asked Active Wiretap 3% 1% Not Asked Not Asked
Figure 9-1: CSI/FBI Survey Conclusion Attacks are like multiple poisons Several of them are fatal Defense is difficult
Viruses and Worms Human Hacking (Break-Ins) Denial-of-Service Attacks Major Attacks Viruses and Worms Human Hacking (Break-Ins) Denial-of-Service Attacks
Figure 9-2: Viruses and Worms Pieces of code that attach to other programs Virus code executes when infected programs execute Infect other programs on the computer Spread to other computers by e-mail attachments, webpage downloads, etc.
Figure 9-2: Viruses and Worms Many viruses spread themselves by sending fake e- mail messages with infected attachments Antivirus programs are needed to scan arriving files Users often fail to keep their computer antivirus programs up to date Antivirus filtering on the e-mail server works even if users are negligent
Figure 9-2: Viruses and Worms Complete programs Self-propagating worms identify victim hosts, jump to them, and install themselves Can do this because hosts have vulnerabilities Vendors develop patches for vulnerabilities but companies often fail to apply them
Figure 9-2: Viruses and Worms Worms take advantage of specific vulnerabilities Firewalls can stop many worms by forbidding access to most ports E-mail worms can get around antivirus filtering
Figure 9-2: Viruses and Worms Blended Threats Combine the spreading characteristics of viruses and worms Payloads Programs that can do damage to infected hosts Erase hard disks, send users to pornography sites if they mistype a URL Trojan horses: exploitation programs disguise themselves as system files
Figure 9-3: Human Break-Ins (Hacking) Viruses and worms rely on one main attack method Humans can keep trying different approaches until they succeed Hacking Breaking into a computer Hacking is intentionally using a computer resource without authorization or in excess of authorization Prosecutable if do a certain amount of damage
Figure 9-3: Human Break-Ins (Hacking) Scanning Phase Send attack probes to map the network and identify possible victim hosts Like a robber casing a neighborhood Finds active IP addresses Identifies type of computer at that address via open ports, etc. Nmap program is popular (Figure 9-4)
Figure 9-4: Nmap Scanning Output IP Range to Scan Type of Scan Identified Host and Open Ports
Figure 9-3: Human Break-Ins (Hacking) The Exploit The Term “Exploit” is Used in Two Ways The actual break-in Exploit is the program used to make the break-in Super user accounts (administrator and root) can do anything If application running with super user privileges is compromised, the attacker gains super user privileges
Figure 9-3: Human Break-Ins (Hacking) After the Break-In Become invisible by deleting log files Create a backdoor (way to get back into the computer) Backdoor account—account with a known password and super user privileges Backdoor program—program to allow reentry; usually Trojanized Do damage at leisure
Denial-of-Service (DoS) Attacks Make a computer or network unavailable to users An exploding threat Rarely: sending a single message to bring down a computer Usually: overload a victim with a flood of messages
Figure 9-5: Distributed Denial-of-Service (DDoS) Flooding Attack Zombie Handler Attack Command Attack Packet Attack Command Attack Packet Attacker 1.34.150.37 Attack Command Victim 60.168.47.47 Attack Command Zombie Attack Packet Handler Attack Command Zombie
Attackers
Figure 9-6: Types of Attackers Traditional attackers: Curious hackers Disgruntled employees and ex-employees Growing number of criminal attackers Potential for far more massive attacks Cyberterror attacks by terrorists Cyberwar by nations
Security Management
Figure 9-7: Planning Principles Security is a Management Issue, Not a Technical Issue Without good management, technology cannot be effective. Like a car. If you don’t know how to drive, not likely to be able to use effectively. Soldiers are not just given weapons. Must be trained extensively in tactics, etc.
Figure 9-7: Planning Principles Plan-Protect-Respond Cycle Three phases endlessly repeating Planning: preparing for defense Protecting: implementing planned protections Responding: stopping attacks and repairing damage when protections fail
Figure 9-7: Planning Principles Risk Analysis Cost of protections should not exceed probable damage Annual probability of damage Damage from a successful incident (Say, $50,000) Times the annual probability of success (say 10%) Gives the probable annual loss ($5,000)
Figure 9-7: Planning Principles Risk Analysis Cost of protection If a protection can reduce the annual probability of damage by a certain amount, up to this amount can be spent on the protection Example Protection A can reduce the annual probability of damage by 50% ($2,500) If Protection A costs $1,000 per year, use it. If Protection A costs $4,000 per year, don’t use it.
Figure 9-7: Planning Principles Comprehensive Security Attacker is intelligent Attacker only has to find one weakness Firm needs comprehensive security to close all avenues of attack
Figure 9-7: Planning Principles Defense in Depth Every protection breaks down sometimes Attacker should have to break through several lines of defense to succeed Providing this protection is called defense in depth Defense 1 (fails) Defense 2
Authentication
Figure 9-8: Authentication and Authorization Server 1. Credentials (Password, etc.) Verifier Applicant Verifier Applicant
Figure 9-8: Authentication and Authorization Server Verifier 2. OK? Applicant Verifier Applicant
Figure 9-8: Authentication and Authorization Server Verifier 3. OK and Authorizations Applicant Verifier Applicant
Figure 9-8: Authentication and Authorization Server Verifier 4. Welcome Applicant Verifier Applicant
Figure 9-9: Password Authentication Passwords Strings of characters Typed to authenticate use of a username (account) on a computer Benefits Ease of use for users (familiar) Inexpensive because built into operating systems
Figure 9-9: Password Authentication Often weak (easy to crack) Word and name passwords are common Can be cracked quickly with dictionary attack Passwords should be complex Mix case, digits, and other keyboard characters ($, #, etc.) Can only be cracked with brute force attacks (trying all possibilities)
Figure 9-9: Password Authentication Passwords should be long Six to eight characters minimum Each added character increases the brute force search time by a factor of up to 75
Figure 9-10: Digital Certificate Authentication User gets secret private key and non-secret public key Digital certificates give the name of a true party and his or her public key
Figure 9-10: Digital Certificate Authentication Testing a Digital Signature Applicant performs a calculation with his or her private key Verifier tests calculation using the public key found in the true party’s digital certificate If the test succeeds, the applicant must be the true party
Figure 9-11: Testing a Digital Signature Digital Certificate Name of True Party Public Key of True Party Digital Signature Created with Private Key of Applicant. Added to each Message. Authentication
Figure 9-10: Digital Certificate Authentication Strong Authentication The strongest method today Expensive and Time-Consuming to Implement Software must be added to clients and servers, and each computer must be configured Expensive because there are so many clients in a firm
Figure 9-10: Digital Certificate Authentication Client Weaknesses Sometimes, only server gets digital certificate Client uses passwords or something else
Figure 9-11: Testing a Digital Signature Verifier must test the digital signature with the public key of the true party. If the test succeeds, the applicant must have the true party’s private key. Only the true party should know this private key; so the applicant must be the true party.
Figure 9-12: Biometric Authentication Based on bodily measurements Promises to dramatically simplify authentication
Figure 9-12: Biometric Authentication Fingerprint Scanning Simple and inexpensive Substantial error rate (misidentification) Often can be fooled fairly easily by impostors Dominates biometrics today
Figure 9-12: Biometric Authentication Iris Scanners Scan the iris (colored part of the eye) Irises are complex, so strong authentication Expensive (Do NOT shine light in your eyes; scanner is a camera.)
Figure 9-12: Biometric Authentication Face Recognition Camera allows analysis of facial structure Can be done surreptitiously— without the knowledge or consent of person being scanned Very high error rate and easy to fool
Figure 9-12: Biometric Authentication Error Rates and Deception Error and deception rates are higher than vendors claim Usefulness of biometrics is uncertain
Firewalls, IDSs, and IPSs
Figure 9-13: Firewall Operation Corporate Network The Internet Permit (Pass) Legitimate Packet IP-H TCP-H Application Message IP-H UDP-H Application Message Deny (Drop) Attack Packet IP-H ICMP Message Arriving Packets Static Packet Filter Firewall Log File
Figure 9-14: Access Control List (ACL) for a Packet Filter Firewall 1. If destination IP address = 60.47.3.9 AND TCP destination port = 80 OR 443, PASS [connection to a public webserver] 2. If ICMP Type = 0, PASS [allow incoming echo reply messages] 3. If TCP destination port = 49153 AND 65535, PASS [allow incoming packets to ephemeral TCP port numbers]
Figure 9-14: Access Control List (ACL) for a Packet Filter Firewall 4. If UDP destination port = 49153 AND 65535, PASS [allow incoming packets to ephemeral UDP port numbers] 5. DENY ALL [deny all other packets]
Figure 9-15: Stateful Firewall Default Operation Internally initiated communication is allowed. X Internal Host Externally initiated communication is stopped. External Host
Figure 9-16: Application Firewalls Examine application layer messages in packets Packet filter firewalls and stateful firewalls do not look at application messages at all This makes them vulnerable to certain attacks
Figure 9-16: Application Firewalls Application Fidelity Requiring the application using a well-known port to be the application that is supposed to use that port For instance, if an application uses Port 80, application firewall requires it to be HTTP, not a peer-to-peer file transfer program or something else This is called enforcing application fidelity
Figure 9-16: Application Firewalls Limited Content Filtering Allow FTP Get commands but stop FTP Put commands Do not allow HTTP connections to black-listed (banned) websites E-mail application server may delete all attachments
Figure 9-16: Application Firewalls Antivirus Scanning Few application firewalls do antivirus filtering Packets also must be passed through separate antivirus filtering programs
Figure 9-17: Defense in Depth with Firewalls Internet Screening Border Router with Packet Filter Firewall Software Application Firewall e-mail, HTTP, etc. Client with Host Firewall Software Main Firewall: Stateful Inspection Firewall Site
Figure 9-18: Firewalls Hardened Server Internet Firewall Allowed Legitimate Packet Attacker IDS Legitimate Packet Hardened Client PC Internal Corporate Network Log File Legitimate Host Network Management Console
Figure 9-18: Firewall Hardened Server Internet Firewall IDS Attack Packet Attacker Denied Attack Packet Hardened Client PC Internal Corporate Network Log File Legitimate Host Network Management Console
Figure 9-18: Intrusion Detection System (IDS) Hardened Server Suspicious Packet Suspicious Packet IDS IDS Attacker Alarm About Suspicious Packet Hardened Client PC Internal Corporate Network Log File Legitimate Host Network Management Console
Figure 9-18: Intrusion Prevention Systems (IPSs) Firewalls stop simple attacks IDSs can identify complex attacks involving multiple packets But many false positives (false alarms) Intrusion prevention systems (IPSs) Like IDSs, can identify complex attacks Unlike IDSs, also stop these attacks Only allowed to stop clearer complex attacks
Figure 9-19: Cryptographic System (SSL/TLS) Applicant (Customer Client) without Digital Certificate Verifier (Merchant Webserver) with Digital Certificate Provides Protection at Transport Layer Protects all Application Traffic That is SSL/TLS-Aware (Mostly HTTP)
Figure 9-19: Cryptographic System (SSL/TLS) Applicant (Customer Client) without Digital Certificate Verifier (Merchant Webserver) with Digital Certificate 1. Negotiation of Security Options (Brief) 2. Merchant Authenticates Self to Customer Uses a Digital Certificate Customer Authentication Is Optional and Uncommon
Figure 9-19: Cryptographic System (SSL/TLS) Applicant (Customer Client) without Digital Certificate Verifier (Merchant Webserver) with Digital Certificate 3. Client Generates Random Session Key Client Sends to Server Encrypted by Merchant’s Public Key 4. Ongoing Communication with Confidentiality and Merchant Digital Signatures
Figure 9-19: Cryptographic System (SSL/TLS) Perspective Initial Hand-Shaking Phases are Very Brief (Milliseconds) The Last Phase (Ongoing Communication) Is Almost All Total Communication
Encryption for Confidentiality
Figure 9-20: Symmetric Key Encryption and Public Key Encryption Symmetric Key Encryption for Confidentiality Symmetric Key Message “Hello” Encryption Method & Key Encrypted Message Interceptor Network Party A Party B Encryption uses a non-secret encryption method and a secret key
Figure 9-20: Symmetric Key Encryption and Public Key Encryption Symmetric Key Encryption for Confidentiality Symmetric Key Encrypted Message Interceptor Network Party A Encrypted Message Interceptor cannot read encrypted messages Party B
Figure 9-20: Symmetric Key Encryption and Public Key Encryption Symmetric Key Encryption for Confidentiality Symmetric Key Message “Hello” Encryption Method & Key Encrypted Message Interceptor Same Symmetric Key Network Party A Encrypted Message Decryption Method & Key Message “Hello” Receiver decrypts the message Using the same encryption message And the same symmetric key Party B
Figure 9-20: Symmetric Key Encryption and Public Key Encryption Public Key Encryption for Confidentiality Encrypt with Party B’s Public Key Decrypt with Party B’s Private Key Encrypted Message Note: Four keys are used to encrypt and decrypt in both directions Party A Party B Decrypt with Party A’s Private Key Encrypted Message Encrypt with Party A’s Public Key
Figure 9-21: Other Aspects of Protection Hardening Servers and Client PCs Setting up computers to protect themselves Server Hardening Patch vulnerabilities Minimize applications running on each server Use host firewalls Backup so that restoration is possible
Figure 9-21: Other Aspects of Protection Hardening Servers and Client PCs Client PC Hardening As with servers, patching vulnerabilities, minimizing applications, having a firewall, and implementing backup Also, a good antivirus program that is updated regularly Client PC users often make errors or sabotage hardening techniques
Figure 9-21: Other Aspects of Protection Vulnerability Testing Protections are difficult to set up correctly Vulnerability testing is attacking your system yourself or through a consultant There must be follow-up to fix vulnerabilities that are discovered
Dealing with attacks that succeed Incident Response Dealing with attacks that succeed
Figure 9-22: Incident Response Response Phases Detecting the attack If not detected, damage will continue unabated IDS or employee reports are common ways to detect attacks Stopping the attack Depends on the attack Reconfiguring firewalls may work
Figure 9-22: Incident Response Response Phase Repairing the damage Sometimes as simple as running a cleanup utility Sometimes, must reformat a server disk and reinstall software Can be very expensive if the attacker has done much damage
Figure 9-22: Incident Response Response Phase Punishing the attackers Easier to punish employees than remote attackers Forensic tools collect data in a manner suitable for legal proceedings
Figure 9-22: Incident Response Major Attacks and CSIRTs Major attacks cannot be handled by the on-duty staff On-duty staff convenes the computer security incident response team (CSIRT) CSIRT has people from security, IT, functional departments, and the legal department
Figure 9-22: Incident Response Disasters Natural and attacker-created disasters Can stop business continuity (operation) Data backup and recovery are crucial for disaster response Dedicated backup facilities versus real-time backup between different sites
Figure 9-22: Incident Response Disasters Business continuity recovery is broader Protecting employees Maintaining or reestablishing communication Providing exact procedures to get the most crucial operations working again in correct order
Topics Covered
Topics Covered A Wide Variety of Attacks Viruses and Worms Hacking (Break-in) Scanning Break-In Exploitation (delete log files, create backdoors, do damage) Denial-of-Service (DoS) Attacks Employee misuse of the Internet Growing in frequency (and viciousness)
Topics Covered A Wide Variety of Attackers Traditional Attackers Wizard attackers Employees and Ex-Employees Criminals (Exploding) Cyberterrorists and National Governments
Topics Covered A Management Issue, not a Technical Issue Planning Technology does not work automatically Planning Risk analysis Comprehensive security Defense in depth
Topics Covered Authentication and Authorization Authentication servers give consistency Passwords (weak) Digital signatures and digital certificates High security but difficult to implement Biometric authentication Could eliminate passwords Error rates and deception
Topics Covered Firewalls Drop and log packets Packet filter firewalls and ACLs Stateful firewalls (dominate for main firewalls today) Application firewalls filter application content Usually do NOT provide antivirus filtering Defense in depth with multiple firewalls IDSs to detect complex attacks IPSs to stop some complex attacks
Topics Covered Cryptographic Systems SSL/TLS Negotiate security parameters Authentication Key exchange Ongoing communication (dominates) SSL/TLS Cryptographic system used in e-commerce Protects HTTP communication
Topics Covered Encryption for Confidentiality Symmetric key encryption Both sides use the same symmetric key Dominates because fast and efficient Public key encryption Each side has a secret private key and a non-secret public key
Topics Covered Hardening Servers and Client PCs Vulnerability Testing Patching vulnerabilities Minimize applications Host firewalls Backup Clients: antivirus filtering (users may sabotage) Vulnerability Testing
Topics Covered Incident Response Detection, stopping, repair, punishment CSIRTs for major attacks to big for the on-duty staff to handle Disaster response and business continuity recovery