After a client sends a connection request (SYN) packet to the server, the server will respond (SYN-ACK) with a sequence number of its choosing, which then must be acknowledge (ACK) by the client. This sequence number is predictable; the attack connects to a service first with its own IP address, records the sequence number chosen and then opens a second connection from a forget IP address. The attack doesn’t see the SYN-ACK (or any other packet) from the server, but can guess the correct responses. If the source IP Address is used for authentication, the attacker can use the one-side communication to break into the server.What attacks can you successfully launch against a server using the above technique?
Answer(s): A
The term Session Hijacking refers to the exploitation of a valid computer session - sometimes also called a session key - to gain unauthorised access to information or services in a computer system. In particular, it is used to refer to the theft of a magic cookie used to authenticate a user to a remote server. It has particular relevance to web developers, as the HTTP cookies used to maintain a session on many web sites can be easily stolen by an attacker using an intermediary computer or with access to the saved cookies on the victim's computer.
Bob waits near a secured door, holding a box. He waits until an employee walks up to the secured door and uses the special card in order to access the restricted area of the target company. Just as the employee opens the door, Bob walks up to the employee (still holding the box) and asks the employee to hold the door open so that he can enter. What is the best way to undermine the social engineering activity of tailgating?
Answer(s): D
Tailgating will not work in small company’s where everyone knows everyone, and neither will it work in very large companies where everyone is required to swipe a card to pass, but it’s a very simple and effective social engineering attack against mid-sized companies where it’s common for one employee not to know everyone. There is two ways of stop this attack either by buying expensive perimeter defense in form of gates that only let on employee pass at every swipe of a card or by educating every employee on a recurring basis.
Liza has forgotten her password to an online bookstore. The web application asks her to key in her email so that they can send her the password. Liza enters her email liza@yahoo.com'. The application displays server error. What is wrong with the web application?
Answer(s): B
All input from web browsers, such as user data from HTML forms and cookies, must be stripped of special characters and HTML tags as described in the following CERT advisories:http://www.cert.org/advisories/CA-1997-25.htmlhttp://www.cert.org/advisories/CA-2000-02.html
You work as security technician at ABC.com. While doing web application testing, you might be required to look through multiple web pages online which can take a long time. Which of the processes listed below would be a more efficient way of doing this type of validation?
Wget is a utility used for mirroring websites, get* doesn’t work, as for the actual FTP command to work there needs to be a space between get and * (ie. get *), get(); is just bogus, that’s a C function that’s written 100% wrong. mget is a command used from “within” ftp itself, ruling out A. Which leaves B use wget, which is designed for mirroring and download files, especially web pages, if used with the –R option (ie. wget –R www.ABC.com) it could mirror a site, all expect protected portions of course.Note: GNU Wget is a free network utility to retrieve files from the World Wide Web using HTTP and FTP and can be used to make mirrors of archives and home pages thus enabling work in the background, after having logged off.
John wishes to install a new application onto his Windows 2000 server.He wants to ensure that any application he uses has not been Trojaned.What can he do to help ensure this?
MD5 was developed by Professor Ronald L. Rivest of MIT. What it does, to quote the executive summary of rfc1321, is: [The MD5 algorithm] takes as input a message of arbitrary length and produces as output a 128-bit "fingerprint" or "message digest" of the input. It is conjectured that it is computationally infeasible to produce two messages having the same message digest, or to produce any message having a given prespecified target message digest. The MD5 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being encrypted with a private (secret) key under a public-key cryptosystem such as RSA. In essence, MD5 is a way to verify data integrity, and is much more reliable than checksum and many other commonly used methods.
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