Pass the ECCouncil CEH v12 312-50v12 Questions and answers with ValidTests

https://blog.mailfence.com/how-do-digital-signatures-work/

https://en.wikipedia.org/wiki/Digital_signature

A digital signature is a mathematical technique used to validate the authenticity and integrity of a message, software, or digital document. It's the digital equivalent of a handwritten signature or stamped seal, but it offers far more inherent security. A digital signature is intended to solve the problem of tampering and impersonation in digital communications.

Digital signatures can provide evidence of origin, identity, and status of electronic documents, transactions, or digital messages. Signers can also use them to acknowledge informed consent.

Digital signatures are based on public-key cryptography, also known as asymmetric cryptography. Two keys are generated using a public key algorithm, such as RSA (Rivest-Shamir-Adleman), creating a mathematically linked pair of keys, one private and one public.

Digital signatures work through public-key cryptography's two mutually authenticating cryptographic keys. The individual who creates the digital signature uses a private key to encrypt signature-related data, while the only way to decrypt that data is with the signer's public key.

A SYN flood attack is a type of denial-of-service (DoS) attack that exploits the TCP handshake process by sending a large number of SYN requests to the target server, without completing the connection. This consumes the connection state tables on the server, preventing it from accepting new connections. The attacker has crafted an automated botnet to simultaneously send ‘s’ SYN packets per second to the server. The server can handle ‘f’ SYN packets per second without any performance issues. If ‘s’ exceeds ‘f’, the network infrastructure begins to show signs of overload. The system’s response time increases exponentially (24k), where ‘k’ represents each additional SYN packet above the ‘f’ limit.

Considering ‘s=500’ and different ‘f’ values, the scenario that is most likely to cause the server to experience overload and significantly increased response times is the one where ‘f=420’. This is because ‘s’ is greater than ‘f’ by 80 packets per second, which means the server cannot handle the incoming traffic and will eventually run out of resources. The response time shoots up (2480 = 281,474,976,710,656 times the normal response time), indicating a system overload.

The other scenarios are less likely or less severe than the one where ‘f=420’. Option A has ‘f=510’, which is greater than ‘s’, so the system stays stable and the response time remains unaffected. Option B has ‘f=495’, which is less than ‘s’ by 5 packets per second, so the response time drastically rises (245 = 32 times the normal response time), indicating a probable system overload, but not as extreme as option D. Option C has ‘f=505’, which is less than ‘s’ by 5 packets per second, so the response time increases but not as drastically (245 = 32 times the normal response time), and the system might still function, albeit slowly. References:

SYN flood DDoS attack | Cloudflare

SYN flood - Wikipedia

What Is a SYN Flood Attack? | F5

What is a SYN flood attack and how to prevent it? | NETSCOUT

Developed by Robert “RSnake” Hansen, Slowloris is DDoS attack software that permits one computer to require down an internet server. Due the straightforward yet elegant nature of this attack, it requires minimal bandwidth to implement and affects the target server’s web server only, with almost no side effects on other services and ports.Slowloris has proven highly-effective against many popular sorts of web server software, including Apache 1.x and 2.x.Over the years, Slowloris has been credited with variety of high-profile server takedowns. Notably, it had been used extensively by Iranian ‘hackivists’ following the 2009 Iranian presidential election to attack Iranian government internet sites .Slowloris works by opening multiple connections to the targeted web server and keeping them open as long as possible. It does this by continuously sending partial HTTP requests, none of which are ever completed. The attacked servers open more and connections open, expecting each of the attack requests to be completed.Periodically, the Slowloris sends subsequent HTTP headers for every request, but never actually completes the request. Ultimately, the targeted server’s maximum concurrent connection pool is filled, and extra (legitimate) connection attempts are denied.By sending partial, as against malformed, packets, Slowloris can easily elapse traditional Intrusion Detection systems.Named after a kind of slow-moving Asian primate, Slowloris really does win the race by moving slowly and steadily. A Slowloris attack must await sockets to be released by legitimate requests before consuming them one by one.For a high-volume internet site , this will take a while . the method are often further slowed if legitimate sessions are reinitiated. But within the end, if the attack is unmitigated, Slowloris—like the tortoise—wins the race.If undetected or unmitigated, Slowloris attacks also can last for long periods of your time . When attacked sockets outing , Slowloris simply reinitiates the connections, continuing to reach the online server until mitigated.Designed for stealth also as efficacy, Slowloris are often modified to send different host headers within the event that a virtual host is targeted, and logs are stored separately for every virtual host.More importantly, within the course of an attack, Slowloris are often set to suppress log file creation. this suggests the attack can catch unmonitored servers off-guard, with none red flags appearing in log file entries.Methods of mitigationImperva’s security services are enabled by reverse proxy technology, used for inspection of all incoming requests on their thanks to the clients’ servers.Imperva’s secured proxy won’t forward any partial connection requests—rendering all Slowloris DDoS attack attempts completely and utterly useless.

The command usage that would best serve your objective to find where the NTP server obtains the time from and to trace the list of NTP servers connected to the network is ntptrace -n -m 5 192.168.1.1. This command usage works as follows:

ntptrace is a tool that determines where a given NTP server gets its time from, and follows the chain of NTP servers back to their master time source. For example, a stratum 0 server, which is a device that directly obtains the time from a physical source, such as an atomic clock or a GPS receiver1.

-n is a flag that outputs host IP addresses instead of host names. This can be useful if the host names are not resolvable or if the IP addresses are more informative1.

-m 5 is a flag that specifies the maximum number of hosts to be traced. This can be useful to limit the output and avoid tracing irrelevant or unreachable hosts1.

192.168.1.1 is the IP address of the NTP server in the demilitarized zone, which is the starting point of the trace. This can be useful to find out the source and the path of the time synchronization for the network system1.

By using this command usage, the output will show the IP addresses, the stratum, the offset, the sync distance, and the reference ID of each NTP server in the chain, up to five hosts. This can provide valuable information about the accuracy, the reliability, and the security of the time service for the network system1.

The other options are not as suitable as option D for the following reasons:

A. ntptrace -m 5 192.168.1.1: This option is similar to option D, but it does not use the -n flag, which means that it will output host names instead of IP addresses. This can be less useful if the host names are not resolvable or if the IP addresses are more informative1.

B. tptrace 192.1681.: This option is incorrect because it uses a wrong tool name and a wrong IP address. tptrace is not a valid tool name, and 192.1681. is not a valid IP address. The correct tool name is ntptrace, and the correct IP address is 192.168.1.11.

C. ntptrace -n localhost: This option is not effective because it uses localhost as the starting point of the trace, which means that it will only show the local host’s time source. This can be useful to check the local host’s time configuration, but it does not help to find out the time source and the trace of the NTP server in the demilitarized zone, which is the objective of this scenario1.

References:

1: ntptrace - trace a chain of NTP servers back to the primary source

A man-in-the-middle attack using forged ICMP and ARP spoofing is a type of network-level session hijacking attack where an attacker inserts their machine into the communication between a client and a server, making it seem like the packets are flowing through the original path. This technique is primarily used to reroute the packets and intercept or modify the data exchanged between the client and the server.

A man-in-the-middle attack using forged ICMP and ARP spoofing works as follows1:

The attacker sends a forged ICMP redirect message to the client, claiming to be the gateway. The ICMP redirect message tells the client to use the attacker’s machine as the next hop for reaching the server’s network. The client updates its routing table accordingly and starts sending packets to the attacker’s machine instead of the gateway.

The attacker also sends a forged ARP reply message to the client, claiming to be the server. The ARP reply message associates the attacker’s MAC address with the server’s IP address. The client updates its ARP cache accordingly and starts sending packets to the attacker’s MAC address instead of the server’s MAC address.

The attacker receives the packets from the client and forwards them to the server, acting as a relay. The attacker can also monitor, modify, or drop the packets as they wish. The server responds to the packets and sends them back to the attacker, who then forwards them to the client. The client and the server are unaware of the attacker’s presence and think they are communicating directly with each other.

Therefore, Jake is studying a man-in-the-middle attack using forged ICMP and ARP spoofing, which is a type of network-level session hijacking attack.

References:

Network or TCP Session Hijacking | Ethical Hacking - GreyCampus

A TCP/IP hijack is an attack that spoofs a server into thinking it’s talking with a sound client, once actually it’s communication with an assaulter that has condemned (or hijacked) the tcp session. Assume that the client has administrator-level privileges, which the attacker needs to steal that authority so as to form a brand new account with root-level access of the server to be used afterward. A tcp Hijacking is sort of a two-phased man-in-the-middle attack. The man-in-the-middle assaulter lurks within the circuit between a shopper and a server so as to work out what port and sequence numbers are being employed for the conversation.

First, the attacker knocks out the client with an attack, like Ping of Death, or ties it up with some reasonably ICMP storm. This renders the client unable to transmit any packets to the server. Then, with the client crashed, the attacker assumes the client’s identity so as to talk with the server. By this suggests, the attacker gains administrator-level access to the server.

One of the most effective means of preventing a hijack attack is to want a secret, that’s a shared secret between the shopper and also the server. looking on the strength of security desired, the key may be used for random exchanges. this is often once a client and server periodically challenge each other, or it will occur with each exchange, like Kerberos.

The deep web is the layer of the online cyberspace that consists of web pages and content that are hidden and unindexed.

Lock-in reflects the inability of the client to migrate from one CSP to another or in-house systems owing to the lack of tools, procedures, standard data formats, applications, and service portability. This threat is related to the inappropriate selection of a CSP, incomplete and non-transparent terms of use, lack of standard mechanisms, etc. (P.2884/2868)

Vulnerability scanning software is a tool that can help security analysts identify and prioritize known vulnerabilities in their systems and applications. However, it is not a perfect solution and has some limitations that need to be considered. One of the most critical limitations is that vulnerability scanning software is not immune to software engineering flaws that might lead to serious vulnerabilities being missed. This means that the software itself might have bugs, errors, or oversights that could affect its accuracy, reliability, or performance. For example, the software might:

Fail to detect some vulnerabilities due to incomplete or outdated databases, incorrect signatures, or insufficient coverage of the target system or application.

Produce false positives or false negatives due to misinterpretation of the scan results, incorrect configuration, or lack of context or validation.

Cause unintended consequences or damage to the target system or application due to intrusive or aggressive scanning techniques, such as exploiting vulnerabilities, modifying data, or crashing services.

Be vulnerable to attacks or compromise by malicious actors who could exploit its weaknesses, tamper with its functionality, or steal its data.

Therefore, the security analyst should be most cautious about this limitation of vulnerability scanning software, as it could lead to a false sense of security, missed opportunities for remediation, or increased exposure to threats. The security analyst should always verify the scan results, use multiple tools and methods, and update and patch the software regularly to mitigate this risk.

References:

[CEHv12 Module 03: Vulnerability Analysis]

7 limitations of vulnerability scanners

The pros and cons of vulnerability scanning tools