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Threats

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This chapter is from the book

Exam Prep Questions

Question 1

The principal source of security threats to a network is

  1. Internal users

  2. The Internet

  3. Script kiddies

  4. The hacker underground

Answer A is correct. The SAFE Blueprint assumes that most threats still originate from within the network. Although publicly available statistics are beginning to indicate that the Internet is an equal source of attacks on major networks, the SAFE Blueprint has not yet adopted that position (eliminating choice B). Script kiddies (choice C) can operate from anywhere, including inside your network. The hacker underground (choice D) likewise can operate from anywhere; one or more members might well have "day jobs" inside your network.

Question 2

Which of these is not an internal threat?

  1. Current employees with bad intentions.

  2. Current contractors who engage in activity beyond the bounds of their contract.

  3. Employees who add unauthorized software to their systems.

  4. Employees with unauthorized business activities piggy-backed on your network.

  5. None of these is correct.

Answer E is correct. Current employees whose intentions are dishonorable (choice A); employees who mismanage their systems by adding unauthorized software (choice C); employees with unauthorized activities, such as charities or businesses running on the business' network (choice D); and contractors who do any of these things (choice B) are all internal threats.

Question 3

Remote users are a security problem because

  1. Their systems are not within your secure perimeter.

  2. They access your network and (possibly) many other networks as well.

  3. They might have additional, nonstandard software applied.

  4. All of these are correct.

Answer D is correct. In this case, you know that because they are remote users, they are not inside the secure network perimeter, making answer A a true statement. Recalling the discussion of internal-only devices being easier to secure, the point was made that controlling access was the key. That logic makes answer A applicable to this question. Answer B was discussed as a specific security problem, in that there is always the possibility that these devices have acquired malware from those other networks. Answer C describes one of the kinds of people who constitute an internal threat—those who modify their operating environment without authorization. Although that was not specifically discussed, it is reasonable, and this question has only one correct answer. Because you know that answers A and B are correct and that answer C is plausible, answer D becomes the best available answer.

Question 4

Script kiddies are best described as which of these? (Choose two.)

  1. Young computer geniuses

  2. Authors of attacks that others can follow

  3. Relatively inexperienced hackers

  4. Hackers who operate other hackers' software

  5. "White hat" hackers who reverse-engineer hack scripts

Answer s C and D are correct. Script kiddies are relatively inexperienced ("kids" instead of mature hackers in the business) who run scripts written by other, more experienced hackers. They often do not understand exactly what they are doing, and they might even try to use Windows commands when they penetrate Unix systems, or Unix commands on Windows systems, because they do know enough to recognize what they see as a command-line prompt. This eliminates answer A. Script writers is an apt description of the hackers in answer B. And so-called "white hat" hackers might reverse-engineer various exploits, but they have no particular relationship to script kiddies.

Question 5

Which of the following is not a threat type?

  1. Unauthorized access

  2. Sniffer

  3. Reconnaissance

  4. Data manipulation

Answer B is correct. The four threat types used by Cisco in the SAFE Blueprint are as follows:

  • Reconnaissance

  • Unauthorized access

  • Denial of service

  • Data manipulation

A packet sniffer (or just sniffer) is a tool for conducting network reconnaissance.

Question 6

Which of the following is not a probing utility used by hackers?

  1. ping

  2. dig

  3. finger

  4. nslookup

  5. nmap

  6. SSH

  7. traceroute

Answer F is correct. All of the other utilities listed can be used on a Unix/Linux system to explore a network. dig is not a valid Windows command, and the Windows version of traceroute is tracert. SSH is the Secure Shell protocol, a means for running an encrypted command-line session between two hosts.

Question 7

Port scans often look for which of the following ports to be open? (Choose three.)

  1. 110—pop3

  2. 135—epmap

  3. 21—Telnet

  4. 443—ssh

  5. 445—microsoft-ds

  6. 21—ftp

Answer s B, E, and F are correct. You might see probes against all of these port numbers in your logs, but the most commonly probed ports tend to be these:

  • 135—epmap

  • 1434—ms-sql-m

  • 137—netbios-ns

  • 80—www

  • 445—microsoft-ds

  • 1433—ms-sql-s

  • 554—rtsp

  • 139—netbios-ssn

  • 21—ftp

  • 1080—socks

Notice that answer C has the incorrect protocol associated with the port—port 21 is FTP, not Telnet. Little things such as this can help you eliminate incorrect answers.

Question 8

Which of the following is not a resource that can be overloaded to create a DoS attack?

  1. Power supply

  2. Input buffers

  3. Bandwidth

  4. CPU cycles

Answer A is correct. Common DoS attacks consume not only bandwidth (as in many packet floods), but also the buffers that hold packets awaiting processing and the CPU cycles with which to process them. Other DoS attacks use malformed packets that can cause the TCP/IP stack to crash; still others consume resources within the stack (such as sending ACKs instead of SYNs). The power supply (answer A) needed for a device is a matter of hardware sufficiency, while DoS attacks typically overwhelm aspects of the software- processing system.

Question 9

Data-manipulation attacks require

  1. Sophisticated knowledge of protocols and their associated header structures

  2. Physical access to a system, to lie to the software creating the packets

  3. Significant amounts of practice, during which mistakes can easily lead to discovery of the hacker "wannabe"

  4. A copy of a simple tool, such as NMapWin

Answer D is correct. Although sophisticated knowledge of protocols and header structures (answer A) is useful, and practice (answer C) never hurts, simple tools are available for mounting an attack: NMapWin is among them. The status bar on NMapWin's GUI even displays the command-line syntax required to execute a command. Also, although physical access is nice, a compromised host on a distant network can be commanded to run nmap (the command-line version of the tool) from afar through nothing more complicated than a Telnet session.

Question 10

Rerouting attacks attempt to manipulate data in what way?

  1. Redirect network traffic to a false location.

  2. Crash the routing tables to disrupt service (a form of DoS).

  3. Span VLAN ports to obtain unauthorized access.

  4. None of these is correct.

Answer A is correct. Although the appearance of a "None of these" or "All of these" choice is tempting because it is not often present, you still must evaluate every answer carefully. Rerouting attacks attempt to redirect traffic from its valid destination to a false one, often for criminal use of the information (credit card or identity theft data) that can be acquired from the victims. Crashing routing tables (answer B) and spanning VLAN ports to obtain unauthorized access are attacks, but they are denial-of-service and unauthorized access attacks, respectively. The question specified a data-manipulation attack.

Question 11

Repudiation is a security problem in what way?

  1. It can lead to routers refusing to communicate with each other (refusal to accept routing updates).

  2. An agreed-upon transaction can be invalidated without difficulty.

  3. It leads to data corruption, requiring restoration from backups.

  4. It can prevent initialization of a VPN.

Answer B is correct. Repudiation occurs when a party to a transaction (such as an e-commerce transaction) asserts that it was not a party to the transaction and that the transaction must be voided. This leads to a security requirement, much like a notary public attesting to someone signing a document, that assures both parties to a transaction that neither can later claim that its participation was falsified. Repudiation has nothing to do with router updates (answer A), data corruption (answer C), or VPN initialization (answer D).

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