Chapter 6: Web Security Security+ Guide to Network Security Fundamentals Second Edition

Objectives  Protect systems  List World Wide Web vulnerabilities  Secure Web communications  Secure instant messaging

Protecting Systems  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 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  The SMTP server on most machines uses sendmail to do the actual sending; this queue is called the sendmail queue

How Works (continued)

 POP3 is a basic protocol that allows users to store a collection of messages on the server. The client connects to the POP3 server and downloads messages onto the local computer. After messages are downloaded, they are generally erased from the POP3 server.

How Works (continued)  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 (IMAP4, port 143) is a more advanced protocol that solves many problems remains on the server can be organized into folders and read from any computer. can be read and replied to while offline. The next time a connection is established, mail is sent.

Vulnerabilities  Several vulnerabilities can be exploited by attackers: Malware Spam Hoaxes

Malware  Because of its ubiquity, has replaced floppy disks as the primary carrier for malware  is the malware transport mechanism of choice for two reasons: 1. Because almost all Internet users have e- mail, it has the broadest base for attacks 2. Malware can use to propagate itself

Malware (continued)  Users must be educated about how malware can enter a system through e- mail and proper policies must be enacted to reduce risk of infection users should never open attachments with these file extensions:.bat,.ade,.usf,.exe,.pif  Antivirus software and firewall products must be installed and properly configured to prevent malicious code from entering the network through e- mail

Spam  The amount of spam (unsolicited ) that flows across the Internet is difficult to judge  The US Congress passed the Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003 (CAN-SPAM) in late 2003

Spam (continued)  According to a Pew memorial Trust survey, almost half of the approximately 30 billion daily messages are spam  Spam is having a negative impact on users: 25% of users say the ever-increasing volume of spam has reduced their overall use of 52% of users indicate spam has made them less trusting of in general 70% of users say spam has made being online unpleasant or annoying

Spam (continued)  Filter s at the edge of the network to prevent spam from entering the SMTP server SPAM, Firewall (Barracuda)  Use a backlist of spammers to block any that originates from their addresses  Sophisticated filters can use Bayesian filtering User divides messages received into two piles, spam and not-spam. The filter looks for words that appear more often in each pile to calculate new messages’ probability of being spam or not spam.

Hoaxes  messages that contain false warnings or fraudulent offerings  Unlike spam, are almost impossible to filter  Defense against hoaxes is to ignore them

Hoaxes (continued)  Any message that appears as though it could not be true probably is not  phishing is also a growing practice  A message that falsely identifies the sender as someone else is sent to unsuspecting recipients

Encryption  Two technologies used to protect e- mail messages as they are being transported: Secure/Multipurpose Internet Mail Extensions Pretty Good Privacy

Secure/MIME (S/MIME)  Protocol that adds digital signatures and encryption to Multipurpose Internet Mail Extension (MIME) messages MIME was originally intended to send non- text files  Provides these features: Digital signatures– Interoperability Message privacy– Seamless integration Tamper detection

Pretty Good Privacy (PGP)  Functions much like S/MIME by encrypting messages using digital signatures  A user can sign an message without encrypting it, verifying the sender but not preventing anyone from seeing the contents  First compresses the message Reduces patterns and enhances resistance to cryptanalysis  Creates a session key (a one-time-only secret key) This key is a number generated from random movements of the mouse and keystrokes typed

Pretty Good Privacy (PGP)  PGP uses a passphrase to encrypt the private key on the local computer  Passphrase: A longer and more secure version of a password Typically composed of multiple words More secure against dictionary attacks

Pretty Good Privacy (PGP) Encryption

Examining WWW Vulnerabilities  Originally, webpages were static and links on one webpage would take you to another static page. Content on the page did not change or move  Dynamic content can also be used by attackers Dynamic content is content that can change, such as animated images or information that customized based on who is viewing the page. Sometimes called repurposed programming (using programming tools in ways more harmful than originally intended)

JavaScript  Popular technology used to make dynamic content  When a Web site that uses JavaScript is accessed, the HTML document with the JavaScript code is downloaded onto the user’s computer  The Web browser then executes that code within the browser using the Virtual Machine (VM)―a Java interpreter

JavaScript (continued)  Several defense mechanisms prevent JavaScript programs from causing serious harm: JavaScript does not support certain capabilities JavaScript has no networking capabilities  Other security concerns remain: JavaScript programs can capture and send user information without the user’s knowledge or authorization JavaScript security is handled by restrictions within the Web browser

JavaScript (continued)

Java Applet  A separate program stored on a Web server and downloaded onto a user’s computer along with HTML code  Can also be made into hostile programs  Sandbox is a defense against a hostile Java applet Surrounds program and keeps it away from private data and other resources on a local computer  Java applet programs should run within a sandbox

Java Applet (continued)

 Two types of Java applets: Unsigned Java applet: program that does not come from a trusted source Signed Java applet: has a digital signature proving the program is from a trusted source and has not been altered  The primary defense against Java applets is using the appropriate settings of the Web browser

Java Applet (continued)

ActiveX  Set of technologies developed by Microsoft  Outgrowth of two other Microsoft technologies: Object Linking and Embedding (OLE) Component Object Model (COM)  Not a programming language but a set of rules for how applications should share information

ActiveX (continued)  ActiveX controls represent a specific way of implementing ActiveX Can perform many of the same functions of a Java applet, but do not run in a sandbox Have full access to Windows operating system  ActiveX controls are managed through Internet Explorer  ActiveX controls should be set to most restricted levels

ActiveX (continued)

Cookies  Computer files that contains user-specific information  Need for cookies is based on Hypertext Transfer Protocol (HTTP)  Instead of the Web server asking the user for this information each time they visits that site, the Web server stores that information in a file on the local computer – dynamic content.  Attackers often target cookies because they can contain sensitive information (usernames and other private info)

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 that site might attempt to get the cookie A-ORG from your hard drivewww.b-org Now known as a third-party cookie because it was not created by Web site that attempts to access the cookie

Common Gateway Interface (CGI)  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)  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

Securing Web Communications  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 2.0 is most widely supported Personal Communications Technology (PCT), developed by Microsoft, is similar to SSL The last version of SSL is/was SSL 3.0

Secure Sockets Layer (SSL)/ Transport Layer Security (TLS)  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  SSL/TLS protocol is made up of two layers TLS Handshake Protocol TLS Record Protocol  The current version of TLS is 1.1 TLS 1.0 is the successor to SSL 3.0

Secure Sockets Layer (SSL)/ Transport Layer Security (TLS)  TLS Handshake Protocol allows authentication between server and client and negotiation of an encryption algorithm and cryptographic keys before any data is transmitted  After the Handshake Protocol sets up the encryption, message authentication code (MAC) and key exchange, the Record Protocol does the compression and encryption  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

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  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

Summary  Protecting basic communication systems is a key to resisting attacks  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)  ActiveX controls present serious security concerns because of the functions that a control can execute  A cookie is a computer file that contains user-specific 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