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Lecture Security+ Certification: Chapter 6 - Trung tâm Athena

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Chapter 6 - Email and web security. The main contents of this chapter include all of the following: Protect e-mail systems, list World Wide Web vulnerabilities, secure web communications, secure instant messaging.

Chapter Email and Web Security Objectives in this chapter ATHENA  Protect e-mail systems  List World Wide Web vulnerabilities  Secure Web communications  Secure instant messaging Protecting E-Mail Systems ATHENA  E-mail has replaced the fax machine as the primary communication tool for businesses  Has also become a prime target of attackers and must be protected How E-Mail Works  Use two Transmission Control Protocol/Internet Protocol (TCP/IP) protocols to send and receive messages • Simple Mail Transfer Protocol (SMTP) handles outgoing mail • Post Office Protocol (POP3 for the current version) handles incoming mail  ATHENA The SMTP server on most machines uses sendmail to the actual sending; this queue is called the sendmail queue How E-Mail Works (continued) ATHENA How E-Mail Works (continued) ATHENA  Sendmail tries to resend queued messages periodically (about every 15 minutes)  Downloaded messages are erased from POP3 server  Deleting retrieved messages from the mail server and storing them on a local computer make it difficult to manage messages from multiple computers  Internet Mail Access Protocol (current version is IMAP4) is a more advanced protocol that solves many problems • E-mail remains on the e-mail server How E-Mail Works (continued) ATHENA  E-mail attachments are documents in binary format (word processing documents, spreadsheets, sound files, pictures)  Non-text documents must be converted into text format before being transmitted  Three bytes from the binary file are extracted and converted to four text characters E-Mail Vulnerabilities  Several e-mail vulnerabilities can be exploited by attackers: • Malware • Spam • Hoaxes ATHENA Malware  Because of its ubiquity, e-mail has replaced floppy disks as the primary carrier for malware  E-mail is the malware transport mechanism of choice for two reasons: • Because almost all Internet users have e-mail, it has the broadest base for attacks • Malware can use e-mail to propagate itself ATHENA Malware (continued)  A worm can enter a user’s computer through an e-mail attachment and send itself to all users listed in the address book or attach itself as a reply to all unread e-mail messages  E-mail clients can be particularly susceptible to macro viruses • A macro is a script that records the steps a user performs • A macro virus uses macros to carry out malicious functions ATHENA Cookies (continued)  Can be used to determine which Web sites you view  First-party cookie is created from the Web site you are currently viewing  Some Web sites attempt to access cookies they did not create • If you went to wwwborg, that site might attempt to get the cookie A-ORG from your hard drive • Now known as a third-party cookie because it was not created by Web site that attempts to access the cookie ATHENA Common Gateway Interface (CGI) ATHENA  Set of rules that describes how a Web server communicates with other software on the server and vice versa  Commonly used to allow a Web server to display information from a database on a Web page or for a user to enter information through a Web form that is deposited in a database Common Gateway Interface (CGI) (continued)  CGI scripts create security risks • Do not filter user input properly • Can issue commands via Web URLs  CGI security can be enhanced by: • Properly configuring CGI • Disabling unnecessary CGI scripts or programs • Checking program code that uses CGI for any vulnerabilities ATHENA 83 Naming Conventions ATHENA  Microsoft Disk Operating System (DOS) limited filenames to eight characters followed by a period and a three-character extension (e.g., Filename.doc)  Called the 83 naming convention  Recent versions of Windows allow filenames to contain up to 256 characters  To maintain backward compatibility with DOS, Windows automatically creates an 83 “alias” filename for every long filename 83 Naming Conventions (continued)  The 83 naming convention introduces a security vulnerability with some Web servers • Microsoft Internet Information Server 40 and other Web servers can inherit privileges from parent directories instead of the requested directory if the requested directory uses a long filename  ATHENA Solution is to disable creation of the 83 alias by making a change in the Windows registry database • In doing so, older programs that not recognize long filenames are not able to access the files or subdirectories Securing Web Communications ATHENA  Most common secure connection uses the Secure Sockets Layer/Transport Layer Security protocol  One implementation is the Hypertext Transport Protocol over Secure Sockets Layer Secure Sockets Layer (SSL)/ Transport Layer Security (TLS)  SSL protocol developed by Netscape to securely transmit documents over the Internet • Uses private key to encrypt data transferred over the SSL connection • Version 20 is most widely supported version • Personal Communications Technology (PCT), developed by Microsoft, is similar to SSL ATHENA Secure Sockets Layer (SSL)/ Transport Layer Security (TLS) (continued)  TLS protocol guarantees privacy and data integrity between applications communicating over the Internet • An extension of SSL; they are often referred to as SSL/TLS  ATHENA SSL/TLS protocol is made up of two layers Secure Sockets Layer (SSL)/ Transport Layer Security (TLS) (continued)  TLS Handshake Protocol allows authentication between server and client and negotiation of an encryption algorithm and cryptographic keys before any data is transmitted  FORTEZZA is a US government security standard that satisfies the Defense Messaging System security architecture • Has cryptographic mechanism that provides message confidentiality, integrity, authentication, and access control to messages, components, and even systems ATHENA Secure Hypertext Transport Protocol (HTTPS)  One common use of SSL is to secure Web HTTP communication between a browser and a Web server • This version is “plain” HTTP sent over SSL/TLS and named Hypertext Transport Protocol over SSL ATHENA  Sometimes designated HTTPS, which is the extension to the HTTP protocol that supports it  Whereas SSL/TLS creates a secure connection between a client and a server over which any amount of data can be sent security, HTTPS is designed to transmit individual messages securely Securing Instant Messaging  Depending on the service, e-mail messages may take several minutes to be posted to the POP3 account  Instant messaging (IM) is a complement to email that overcomes these • Allows sender to enter short messages that the recipient sees and can respond to immediately ATHENA Securing Instant Messaging (continued)  Some tasks that you can perform with IM: • • • • • • ATHENA Chat Images Sounds Files Talk Streaming content Securing Instant Messaging (continued)  Steps to secure IM include: • Keep the IM server within the organization’s firewall and only permit users to send and receive messages with trusted internal workers • Enable IM virus scanning • Block all IM file transfers • Encrypt messages ATHENA Summary ATHENA  Protecting basic communication systems is a key to resisting attacks  E-mail attacks can be malware, spam, or hoaxes  Web vulnerabilities can open systems up to a variety of attacks  A Java applet is a separate program stored on the Web server and downloaded onto the user’s computer along with the HTML code Summary (continued) ATHENA  ActiveX controls present serious security concerns because of the functions that a control can execute  A cookie is a computer file that contains userspecific information  CGI is a set of rules that describe how a Web server communicates with other software on the server  The popularity of IM has made this a tool that many organizations are now using with e-mail ... from their e-mail addresses  Sophisticated e-mail filters can use Bayesian filtering • User divides e-mail messages received into two piles, spam and not-spam ATHENA Hoaxes ATHENA  E-mail messages...Objectives in this chapter ATHENA  Protect e-mail systems  List World Wide Web vulnerabilities  Secure Web communications  Secure instant messaging Protecting E-Mail Systems ATHENA  E-mail has replaced... IMAP4) is a more advanced protocol that solves many problems • E-mail remains on the e-mail server How E-Mail Works (continued) ATHENA  E-mail attachments are documents in binary format (word processing

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