CNIT 123: 8: Desktop and Server OS Vulnerabilites
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Chapter 8 of 'Hands-On Ethical Hacking and Network Defense' discusses vulnerabilities in Windows and Linux operating systems, emphasizing the importance of identifying, fixing, and hardening these systems against threats. It covers various vulnerabilities, best practices for patch management, antivirus solutions, and tools for identifying security issues for both operating systems. Additionally, the chapter highlights the need for user awareness training and maintaining up-to-date systems to mitigate risks.
CNIT 123: 8: Desktop and Server OS Vulnerabilites
- 1. Hands-On Ethical Hacking and Network Defense Second Edition Chapter 8 Desktop and Server OS Vulnerabilities Last updated 3-14-15 Last updated 10-6-16
- 2. Objectives • After reading this chapter and completing the exercises, you will be able to: – Describe vulnerabilities of Windows and Linux operating systems – Identify specific vulnerabilities and explain ways to fix them – Explain techniques to harden systems against Windows and Linux vulnerabilities
- 4. Windows OS Vulnerabilities • Many Windows OSs have serious vulnerabilities – Windows 2000 and earlier • Administrators must disable, reconfigure, or uninstall services and features – Windows XP, Vista; Server 2003, 2008, and 2012; Windows 7, 8, and 10 • Most services and features are disabled by default
- 5. CVE List • Link Ch 8zk
- 6. Windows File Systems • File system – Stores and manages information • User created • OS files needed to boot – Most vital part of any OS • Can be a vulnerability
- 7. File Allocation Table • Original Microsoft file system – Supported by nearly all desktop and server OS's – Standard file system for most removable media • Other than CDs and DVDs – Later versions provide for larger file and disk sizes • Most serious shortcoming – Doesn't support file-level access control lists (ACLs) • Necessary for setting permissions on files • Multiuser environment use results in vulnerability
- 8. NTFS • New Technology File System (NTFS) – First released as high-end file system • Added support for larger files, disk volumes, and ACL file security • Subsequent Windows versions – Included upgrades for compression, journaling, file- level encryption, and self-healing • Alternate data streams (ADSs) – Can “stream” (hide) information behind existing files • Without affecting function, size, or other information – Several detection methods
- 9. ADS Demo
- 10. Remote Procedure Call • Interprocess communication mechanism – Allows a program running on one host to run code on a remote host • Worm that exploited RPC – Conficker worm • Microsoft Baseline Security Analyzer – Determines if system is vulnerable due to an RPC- related issue
- 11. Pass The Hash
- 12. Credential Re-Use (link Ch 8zh)
- 13. Silos (link Ch 8zh)
- 14. NetBIOS • Software loaded into memory – Enables computer program to interact with network resource or device • NetBIOS isn’t a protocol – Interface to a network protocol • NetBios Extended User Interface (NetBEUI) – Fast, efficient network protocol – Allows NetBIOS packets to be transmitted over TCP/IP – NBT is NetBIOS over TCP
- 15. NetBIOS (cont’d.) • Systems running newer Windows OSs – Vista, Server 2008, Windows 7, and later versions – Share files and resources without using NetBIOS • NetBIOS is still used for backward compatibility – Companies use old machines
- 16. Server Message Block • Used to share files – Usually runs on top of: • NetBIOS • NetBEUI, or • TCP/IP • Several hacking tools target SMB – L0phtcrack’s SMB Packet Capture utility and SMBRelay • It took Microsoft seven years to patch these
- 17. Server Message Block (cont’d.) • SMB2 – Introduced in Windows Vista – Several new features – Faster and more efficient • Windows 7 – Microsoft avoided reusing code – Still allowed backward capability • Windows XP Mode – Spectacular DoS vulnerabilities • Links Ch 8za-8zc
- 18. Laurent Gaffié's Fuzzer • Look how easy it is! • From Link Ch 8zb
- 19. Common Internet File System • Standard protocol – Replaced SMB for Windows 2000 Server and later – SMB is still used for backward compatibility – Described as just a renaming of SMB by Wikipedia (link Ch 8z) • Remote file system protocol – Enables sharing of network resources over the Internet • Relies on other protocols to handle service announcements – Notifies users of available resources
- 20. Common Internet File System (cont’d.) • Enhancements – Locking features – Caching and read-ahead/write-behind – Support for fault tolerance – Capability to run more efficiently over dial-up – Support for anonymous and authenticated access • Server security methods – Share-level security (folder password) – User-level security (username and password)
- 21. Common Internet File System (cont’d.) • Attackers look for servers designated as domain controllers – Severs handle authentication • Windows Server 2003 and 2008 – Domain controller uses a global catalog (GC) server • Locates resources among many objects
- 22. Domain Controller Ports • By default, Windows Server 2003 and 2008 domain controllers using CIFS listen on the following ports – DNS (port 53) – HTTP (port 80) – Kerberos (port 88) – RPC (port 135) – NetBIOS Name Service (port 137) – NetBIOS Datagram Service (port 139) – LDAP (port 389) – HTTPS (port 443) – SMB/ CIFS (port 445) – LDAP over SSL (port 636) – Active Directory global catalog (port 3268)
- 23. Null Sessions • Anonymous connection established without credentials – Used to display information about users, groups, shares, and password policies – Necessary only if networks need to support older Windows versions • To enumerate NetBIOS vulnerabilities use: – Nbtstat, Net view, Netstat, Ping, Pathping, and Telnet commands
- 24. Web Services • IIS installs with critical security vulnerabilities – IIS Lockdown Wizard • Locks down IIS versions 4.0 and 5.0 • IIS 6.0 and later versions – Installs with a “secure by default” mode – Previous versions left crucial security holes • Keeping a system patched is important • Configure only needed services
- 25. SQL Server • Many potential vulnerabilities – Null System Administrator (SA) password • SA access through SA account • SA with blank password by default on versions prior to SQL Server 2005 – Gives attackers administrative access • Database and database server
- 26. Buffer Overflows • Data is written to a buffer and corrupts data in memory next to allocated buffer – Normally, occurs when copying strings of characters from one buffer to another • Functions don't verify text fits – Attackers run shell code • C and C++ – Lack built-in protection against overwriting data in memory
- 27. Passwords and Authentication • Weakest security link in any network – Authorized users • Most difficult to secure • Relies on people – Companies should take steps to address it
- 28. Passwords and Authentication (cont’d.) • Comprehensive password policy is critical – Should include: • Change passwords regularly • Require at least six characters (too short!) • Require complex passwords • Passwords can’t be common words, dictionary words, slang, jargon, or dialect • Passwords must not be identified with a user • Never write it down or store it online or in a file • Do not reveal it to anyone • Use caution when logging on and limit reuse
- 29. Passwords and Authentication (cont’d.) • Configure domain controllers – Enforce password age, length, and complexity • Password policy aspects that can be enforced: – Account lockout threshold • Set number of failed attempts before account is disabled temporarily – Account lockout duration • Set period of time account is locked out after failed logon attempts • Disable LM Hashes
- 30. Tools for Identifying Vulnerabilities in Windows
- 31. Tools for Identifying Vulnerabilities in Windows • Many tools are available – Using more than one is advisable • Using several tools – Helps pinpoint problems more accurately
- 32. Built-in Windows Tools • Microsoft Baseline Security Analyzer (MBSA) – Capable of checking for: • Patches • Security updates • Configuration errors • Blank or weak passwords
- 33. Figure 8-1 Checks available in MBSA
- 34. Table 8-2 Checks performed by MBSA in full-scan mode
- 35. Table 8-2 Checks performed by MBSA in full-scan mode (cont’d.)
- 36. Using MBSA • System must meet minimum requirements – Before installing • After installing, MBSA can: – Scan itself – Scan other computers remotely – Be scanned remotely
- 37. Best Practices for Hardening Windows Systems
- 38. Best Practices for Hardening Windows Systems • Penetration tester – Finds and reports vulnerabilities • Security tester – Finds vulnerabilities – Gives recommendations for correcting them
- 39. Patching Systems • Best way to keep systems secure – Keep up to date • Attackers take advantage of known vulnerabilities • Options for small networks – Accessing Windows Update manually – Configure Automatic Updates • Options for large networks – Systems Management Server (SMS) – Windows Software Update Service (WSUS) • Third-party patch management solutions
- 40. Antivirus Solutions • Antivirus solution is essential – Small networks • Desktop antivirus tool with automatic updates – Large networks • Require corporate-level solution • Antivirus tools – Almost useless if not updated regularly
- 41. PUPs (Potentially Unwanted Programs) • Programs that come bundled with freeware • Not technically viruses or illegal • Most antivirus won't block them by default
- 42. • Link Ch 8zi, 8zj
- 43. Enable Logging and Review Logs Regularly • Important step for monitoring critical areas – Performance – Traffic patterns – Possible security breaches • Can have negative impact on performance • Review regularly – Signs of intrusion or problems • Use log-monitoring tool
- 44. Disable Unused Services and Filtering Ports • Disable unneeded services • Delete unnecessary applications or scripts – Unused applications are invitations for attacks • Reducing the attack surface – Open only what needs to be open, and close everything else • Filter out unnecessary ports – Make sure perimeter routers filter out ports 137 to 139 and 445
- 45. Other Security Best Practices • Other practices include: – Delete unused scripts and sample applications – Delete default hidden shares – Use different naming scheme and passwords for public interfaces – Be careful of default permissions – Use appropriate packet-filtering techniques – Use available tools to assess system security – Disable Guest account
- 46. Other Security Best Practices (cont’d.) • Other practices include (cont’d.): – Rename (or disable) default Administrator account – Make sure there are no accounts with blank passwords – Use Windows group policies – Develop a comprehensive security awareness program – Keep up with emerging threats
- 47. Microsoft Security Intelligence Report, Volume 20 July through December, 2015
- 55. Linux OS Vulnerabilities • Linux can be made more secure – Awareness of vulnerabilities – Keep current on new releases and fixes • Many versions are available – Differences ranging from slight to major • It’s important to understand basics – Run control and service configuration – Directory structure and file system – Basic shell commands and scripting – Package management
- 56. Samba • Open-source implementation of CIFS – Created in 1992 • Allows sharing resources over a network – Security professionals should have basic knowledge of SMB and Samba • Many companies have a mixed environment of Windows and *nix systems • Used to “trick” Windows services into believing *nix resources are Windows resources
- 57. Tools for Identifying Linux Vulnerabilities • CVE Web site – Source for discovering possible attacker avenues Table 8-4 Linux vulnerabilities found at CVE
- 58. Tools for Identifying Linux Vulnerabilities (cont’d.) • OpenVAS can enumerate multiple OSs – Security tester using enumeration tools can: • Identify a computer on the network by using port scanning and zone transfers • Identify the OS by conducting port scanning • Identify via enumeration any logon accounts • Learn names of shared folders by using enumeration • Identify services running
- 59. Figure 8-5 Viewing security warning details
- 60. Figure 8-6 OpenVAS revealing a security hole resulting from a Firefox vulnerability
- 61. Figure 8-7 OpenVAS revealing a security hole resulting from a DHCP client vulnerability
- 62. Checking for Trojan Programs • Most Trojan programs perform one or more of the following: – Allow remote administration of attacked system – Create a file server on attacked computer • Files can be loaded and downloaded – Steal passwords from attacked system • E-mail them to attacker – Log keystrokes • E-mail results or store them in a hidden file the attacker can access remotely
- 63. Checking for Trojan Programs (cont’d.) • Linux Trojan programs – Sometimes disguised as legitimate programs – Contain program code that can wipe out file systems – More difficult to detect today • Protecting against identified Trojan programs is easier • Rootkits containing Trojan binary programs – More dangerous – Attackers hide tools • Perform further attacks • Have access to backdoor programs
- 64. More Countermeasures Against Linux Attacks • Most critical tasks: – User awareness training – Keeping current – Configuring systems to improve security
- 65. User Awareness Training • Inform users – No information should be given to outsiders • Knowing OS makes attacks easier – Be suspicious of people asking questions • Verify who they are talking to • Call them back
- 66. Keeping Current • As soon as a vulnerability is discovered and posted – OS vendors notify customers • Upgrades • Patches – Installing fixes promptly is essential • Linux distributions – Most have warning methods
- 67. Secure Configuration • Many methods to help prevent intrusion – Vulnerability scanners – Built-in Linux tools – Free benchmark tools • Center for Internet Security – Security Blanket • Trusted Computer Solutions