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Q241. An attacker is attempting to telnet into a corporation’s system in the DMZ. The attacker doesn’t want to get caught and is spoofing his IP address. After numerous tries he remains unsuccessful in connecting to the system. The attacker rechecks that the target system is actually listening on Port 23 and he verifies it with both nmap and hping2. He is still unable to connect to the target system.
What is the most probable reason?
A. The firewall is blocking port 23 to that system.
B. He cannot spoof his IP and successfully use TCP.
C. He needs to use an automated tool to telnet in.
D. He is attacking an operating system that does not reply to telnet even when open.
Answer: B
Explanation: Spoofing your IP will only work if you don’t need to get an answer from the target system. In this case the answer (login prompt) from the telnet session will be sent to the “real” location of the IP address that you are showing as the connection initiator.
Q242. Bob is a Junior Administrator at ABC Company. On One of Linux machine he entered the following firewall rules:
iptables –t filter –A INPUT -p tcp --dport 23 –j DROP
Why he entered the above line?
A. To accept the Telnet connection
B. To deny the Telnet connection
C. The accept all connection except telnet connection
D. None of Above
Answer: B
Explanation: -t, --table
This option specifies the packet matching table which the command should operate on. If the kernel is configured with automatic module loading, an attempt will be made to load the appropriate module for that table if it is not already there. The tables are as follows: filter This is the default table, and contains the built-in chains INPUT (for packets coming into the box itself), FORWARD (for packets being routed through the box), and OUTPUT (for locally-generated packets). nat This table is consulted when a packet which is creates a new connection is encountered. It consists of three built-ins: PREROUTING (for altering packets as soon as they come in), OUTPUT (for altering locally-generated packets before routing), and POSTROUTING (for altering packets as they are about to go out). mangle This table is used for specialized packet alteration. It has two built-in chains: PREROUTING (for altering incoming packets before routing) and OUTPUT (for altering locally-generated packets before routing).
-A, --append
Append one or more rules to the end of the selected chain. When the source and/or destination names resolve to more than one address, a rule will be added for each possible address combination. -p, --protocol [!] protocol The protocol of the rule or of the packet to check. The specified protocol can be one of tcp, udp, icmp, or all, or it can be a numeric value, representing one of these protocols or a different one. Also a protocol name from /etc/protocols is allowed. A "!" argument before the protocol inverts the test. The number zero is equivalent to all. Protocol all will match with all protocols and is taken as default when this option is omitted. All may not be used in in combination with the check command. --destination-port [!] [port[:port]] Destination port or port range specification. The flag --dport is an alias for this option. -j, --jump target
This specifies the target of the rule; ie. what to do if the packet matches it. The target can be a user-defined chain (not the one this rule is in), one of the special builtin targets which decide the fate of the packet immediately, or an extension (see EXTENSIONS below). If this option is omitted in a rule, then matching the rule will have no effect on the packet's fate, but the counters on the rule will be incremented.
Q243. The network administrator at Spears Technology, Inc has configured the default gateway Cisco Router’s access-list as below:
You are tried to conduct security testing on their network. You successfully brute-force for SNMP community string using a SNMP crack tool. The access-list configured at the router prevents you from establishing a successful connection.
You want to retrieve the Cisco Configuration from the router. How would you proceed?
A. Send a customized SNMP set request with spoofed source IP Address in the range-
192.168.1.0
B. Run a network sniffer and capture the returned traffic with the configuration file from the router
C. Run Generic Routing Encapsulation (GRE) tunneling protocol from your computer to the router masking your IP address
D. Use the Cisco’s TFTP default password to connect and download the configuration file
Answer: AB
Explanation: SNMP is allowed only by access-list 1. Therefore you need to spoof a 192.168.1.0/24 address and then sniff the reply from the gateway.
Q244. What is a sheepdip?
A. It is another name for Honeynet
B. It is a machine used to coordinate honeynets
C. It is the process of checking physical media for virus before they are used in a computer
D. None of the above
Answer: C
Explanation: Also known as a footbath, a sheepdip is the process of checking physical media, such as floppy disks or CD-ROMs, for viruses before they are used in a computer. Typically, a computer that sheepdips is used only for that process and nothing else and is isolated from the other computers, meaning it is not connected to the network. Most sheepdips use at least two different antivirus programs in order to increase effectiveness.
Q245. Steven, a security analyst for XYZ associates, is analyzing packets captured by Ethereal on a Linux Server inside his network when the server starts to slow down tremendously. Steven examines the following Ethereal captures:
A. Smurf Attack
B. ARP Spoofing
C. Ping of Death
D. SYN Flood
Answer: A
Explanation: A perpetrator is sending a large amount of ICMP echo (ping) traffic to IP broadcast addresses, all of it having a spoofed source address of the intended victim. If the routing device delivering traffic to those broadcast addresses performs the IP broadcast to layer 2 broadcast function, most hosts on that IP network will take the ICMP echo request and reply to it with an echo reply, multiplying the traffic by the number of hosts responding.
Topic 9, Social Engineering
303. Your boss at ABC.com asks you what are the three stages of Reverse Social Engineering.
A. Sabotage, advertising, Assisting
B. Sabotage, Advertising, Covering
C. Sabotage, Assisting, Billing D. Sabotage, Advertising, Covering
Answer: A
Explanation: Typical social interaction dictates that if someone gives us something then it is only right for us to return the favour. This is known as reverse social engineering, when an attacker sets up a situation where the victim encounters a problem, they ask the attacker for help and once the problem is solved the victim then feels obliged to give the information requested by the attacker.
Q246. The SYN Flood attack sends TCP connections requests faster than a machine can process them.
Attacker creates a random source address for each packet. SYN flag set in each packet is a request to open a new connection to the server from the spoofed IP Address Victim responds to spoofed IP Address then waits for confirmation that never arrives (timeout wait is about 3 minutes) Victim’s connection table fills up waiting for replies and ignores new connection legitimate users are ignored and will not be able to access the server
How do you protect your network against SYN Flood attacks?
A. SYN cookies. Instead of allocating a record, send a SYN-ACK with a carefully constructed sequence number generated as a hash of the clients IP Address port number and other information. When the client responds with a normal ACK, that special sequence number will be included, which the server then verifies. Thus the server first allocates memory on the third packet of the handshake, not the first.
B. RST cookies – The server sends a wrong SYN|ACK back to the client. The client should then generate a RST packet telling the server that something is wrong. At this point, the server knows the client is valid and will now accept incoming connections from that client normally.
C. Micro Blocks. Instead of allocating a complete connection, simply allocate a micro-record of 16-bytes for the incoming SYN object.
D. Stack Tweaking. TCP can be tweaked in order to reduce the effect of SYN floods. Reduce the timeout before a stack frees up the memory allocated for a connection.
Answer: ABCD
Explanation: All above helps protecting against SYN flood attacks. Most TCP/IP stacks today are already tweaked to make it harder to perform a SYN flood DOS attack against a target.
Q247. Neil is closely monitoring his firewall rules and logs on a regular basis. Some of the users have complained to Neil that there are a few employees who are visiting offensive web site during work hours, without any consideration for others. Neil knows that he has an up-to-date content filtering system and such access should not be authorized. What type of technique might be used by these offenders to access the Internet without restriction?
A. They are using UDP that is always authorized at the firewall
B. They are using an older version of Internet Explorer that allow them to bypass the proxy server
C. They have been able to compromise the firewall, modify the rules, and give themselves proper access
D. They are using tunneling software that allows them to communicate with protocols in a way it was not intended
Answer: D
Explanation: This can be accomplished by, for example, tunneling the http traffic over SSH if you have a SSH server answering to your connection, you enable dynamic forwarding in the ssh client and configure Internet Explorer to use a SOCKS Proxy for network traffic.
Q248. You are programming a buffer overflow exploit and you want to create a NOP sled of 200 bytes in the program exploit.c
What is the hexadecimal value of NOP instruction?
A. 0x60
B. 0x80
C. 0x70
D. 0x90
Answer: D
Q249. Which one of the following network attacks takes advantages of weaknesses in the fragment reassembly functionality of the TCP/IP protocol stack?
A. Teardrop
B. Smurf
C. Ping of Death
D. SYN flood
E. SNMP Attack
Answer: A
Explanation: The teardrop attack uses overlapping packet fragments to confuse a target system and cause the system to reboot or crash.
Q250. SNMP is a protocol used to query hosts, servers and devices about performance or health status data. Hackers have used this protocol for a long time to gather great amount of information about remote hosts. Which of the following features makes this possible?
A. It is susceptible to sniffing
B. It uses TCP as the underlying protocol
C. It is used by ALL devices on the market
D. It uses a community string sent as clear text
Answer: AD
Explanation: SNMP uses UDP, not TCP, and even though many devices uses SNMP not ALL devices use it and it can be disabled on most of the devices that does use it. However SNMP is susceptible to sniffing and the community string (which can be said acts as a password) is sent in clear text.
Q251. ViruXine.W32 virus hides their presence by changing the underlying executable code. This Virus code mutates while keeping the original algorithm intact, the code changes itself each time it runs, but the function of the code (its semantics) will not change at all.
Here is a section of the Virus code:
What is this technique called?
A. Polymorphic Virus
B. Metamorphic Virus
C. Dravidic Virus
D. Stealth Virus
Answer: A
Q252. 802.11b is considered a ____________ protocol.
A. Connectionless
B. Secure
C. Unsecure
D. Token ring based
E. Unreliable
Answer: C
Explanation: 802.11b is an insecure protocol. It has many weaknesses that can be used by a hacker.
Q253. Michael is the security administrator for the for ABC company. Michael has been charged with strengthening the company’s security policies, including its password policies. Due to certain legacy applications. Michael was only able to enforce a password group policy in Active Directory with a minimum of 10 characters. He has informed the company’s employes, however that the new password policy requires that everyone must have complex passwords with at least 14 characters. Michael wants to ensure that everyone is using complex passwords that meet the new security policy requirements. Michael has just logged on to one of the network’s domain controllers and is about to run the following command:
What will this command accomplish?
A. Dumps SAM password hashes to pwd.txt
B. Password history file is piped to pwd.txt
C. Dumps Active Directory password hashes to pwd.txt
D. Internet cache file is piped to pwd.txt
Answer: A
Explanation: Pwdump is a hack tool that is used to grab Windows password hashes from a remote Windows computer. Pwdump > pwd.txt will redirect the output from pwdump to a text file named pwd.txt
Q254. SNMP is a protocol used to query hosts, servers, and devices about performance or health status data. This protocol has long been used by hackers to gather great amount of information about remote hosts.
Which of the following features makes this possible? (Choose two)
A. It used TCP as the underlying protocol.
B. It uses community string that is transmitted in clear text.
C. It is susceptible to sniffing.
D. It is used by all network devices on the market.
Answer: BC
Explanation: Simple Network Management Protocol (SNMP) is a protocol which can be used by administrators to remotely manage a computer or network device. There are typically 2 modes of remote SNMP monitoring. These modes are roughly 'READ' and 'WRITE' (or PUBLIC and PRIVATE). If an attacker is able to guess a PUBLIC community string, they would be able to read SNMP data (depending on which MIBs are installed) from the remote device. This information might include system time, IP addresses, interfaces, processes running, etc. Version 1 of SNMP has been criticized for its poor security. Authentication of clients is performed only by a "community string", in effect a type of password, which is transmitted in cleartext.
Q255. 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?
A. Compare the file's MD5 signature with the one published on the distribution media
B. Obtain the application via SSL
C. Compare the file's virus signature with the one published on the distribution media
D. Obtain the application from a CD-ROM disc
Answer: A
Explanation: 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.