ECCouncil 312-50v12 - Certified Ethical Hacker Exam (CEHv12)

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

This is a fairly simple question. You must to understand what a subnet mask is and how it works.

A subnetwork or subnet is a logical subdivision of an IP network.The practice of dividing a network into two or more networks is called subnetting.

Computers that belong to the same subnet are addressed with an identical most-significant bit-group in their IP addresses. This results in the logical division of an IP address into two fields: the network number or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.

The routing prefix may be expressed in Classless Inter-Domain Routing (CIDR) notation written as the first address of a network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 198.51.100.0/24 is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. The IPv6 address specification 2001:db8::/32 is a large address block with 296 addresses, having a 32-bit routing prefix.

For IPv4, a network may also be characterized by its subnet mask or netmask, which is the bitmask that when applied by a bitwise AND operation to any IP address in the network, yields the routing prefix. Subnet masks are also expressed in dot-decimal notation like an address. For example, 255.255.255.0 is the subnet mask for the prefix 198.51.100.0/24.

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The attack scenario is best described as Instant Messenger Applications, and the measure that could have prevented it is verifying the sender’s identity before opening any files. Instant Messenger Applications are communication tools that allow users to exchange text, voice, video, and file messages in real time. However, they can also be used as attack vectors for spreading malware, such as viruses, worms, or Trojans, by exploiting the trust and familiarity between the users. In this scenario, the attacker compromised one of the team member’s messenger account and used it to send malicious files to the other team members, who may have opened them without suspicion, thus infecting their systems. This type of attack is also known as an instant messaging worm12.

To prevent this type of attack, the users should verify the sender’s identity before opening any files sent through instant messenger applications. This can be done by checking the sender’s profile, asking for confirmation, or using a secure channel. Additionally, the users should also follow other security tips, such as using strong passwords, updating the application software, scanning the files with antivirus software, and reporting any suspicious activity34.

References:

1: Instant Messaging Worm - Techopedia

2: Cybersecurity’s Silent Foe: A Comprehensive Guide to Computer Worms | Silent Quadrant

3: Instant Messenger Hacks: 10 Security Tips to Protect Yourself - MUO

4: Increased phishing attacks on instant messaging platforms: how to prevent them | Think Digital Partners

The hacker could have used the technique of manipulating white spaces in SQL queries to bypass signature detection. This technique involves inserting, removing, or replacing white spaces in SQL queries with other characters or symbols that are either ignored or interpreted as white spaces by the SQL engine, but not by the signature-based IDS. This way, the hacker can alter the appearance of the query and evade the pattern matching of the IDS, while preserving the functionality and logic of the query. For example, the hacker could replace the space character with a tab character, a newline character, a comment symbol, or a URL-encoded value, such as %2012.

The other options are not correct for the following reasons:

A. Utilizing the char encoding function to convert hexadecimal and decimal values into characters that pass-through SQL engine parsing: This option is not feasible because the char encoding function is not supported by all SQL engines, and it may not be able to convert all hexadecimal and decimal values into valid characters. Moreover, the char encoding function may not be able to bypass the signature detection of the IDS, as it may still match the keywords or syntax of the SQL query3.

B. Using the URL encoding method to replace characters with their ASCII codes in hexadecimal form: This option is not effective because the URL encoding method is not applicable to SQL queries, as it is designed for encoding special characters in URLs. The URL encoding method may not be able to replace all characters with their ASCII codes, and it may not be able to preserve the functionality and logic of the SQL query. Furthermore, the URL encoding method may not be able to evade the signature detection of the IDS, as it may still match the keywords or syntax of the SQL query4.

C. Implementing sophisticated matches such as “OR ‘john’ = john" in place of classical matches like “OR 1-1”: This option is not advanced because it is a common and basic SQL injection technique that does not involve any evasion or obfuscation. This technique involves injecting a logical expression that is always true, such as “OR ‘john’ = john” or “OR 1-1”, to bypass the authentication or authorization checks of the SQL query. However, this technique may not be able to bypass the signature detection of the IDS, as it may easily match the keywords or syntax of the SQL query.

References:

1: SQL Injection Evasion Detection - F5

2: Mastering SQL Injection with SQLmap: A Comprehensive Evasion Techniques Cheatsheet

3: SQL Injection Prevention - OWASP Cheat Sheet Series

4: URL Encoding - W3Schools

: SQL Injection - OWASP Foundation

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.

An advanced persistent threat (APT) may be a broad term wont to describe AN attack campaign within which an intruder, or team of intruders, establishes a bootleg, long presence on a network so as to mine sensitive knowledge.

The targets of those assaults, that square measure terribly fastidiously chosen and researched, usually embrace massive enterprises or governmental networks. the implications of such intrusions square measure huge, and include:

Intellectual property thieving (e.g., trade secrets or patents)

Compromised sensitive info (e.g., worker and user personal data)

The sabotaging of essential structure infrastructures (e.g., information deletion)

Total website takeovers

Executing an APT assault needs additional resources than a regular internet application attack. The perpetrators square measure typically groups of intimate cybercriminals having substantial resource. Some APT attacks square measure government-funded and used as cyber warfare weapons.

APT attacks dissent from ancient internet application threats, in that:

They’re considerably additional advanced.

They’re not hit and run attacks—once a network is infiltrated, the culprit remains so as to realize the maximum amount info as potential.

They’re manually dead (not automated) against a selected mark and indiscriminately launched against an outsized pool of targets.

They typically aim to infiltrate a complete network, as opposition one specific half.

More common attacks, like remote file inclusion (RFI), SQL injection and cross-site scripting (XSS), square measure oftentimes employed by perpetrators to ascertain a footing in a very targeted network. Next, Trojans and backdoor shells square measure typically wont to expand that foothold and make a persistent presence inside the targeted perimeter.

The most effective attack method for the penetration tester to exploit these vulnerabilities and attempt unauthorized access would be to execute a Brute Force attack, leveraging the lack of account lockout policy and the verbose error messages to guess the correct credentials. A Brute Force attack is a hacking method that uses trial and error to crack passwords, login credentials, or encryption keys. It is a simple yet reliable tactic for gaining unauthorized access to individual accounts and organizations’ systems and networks1. In this scenario, the tester can take advantage of the fact that the application does not lock out users after multiple failed login attempts, which means the tester can try as many combinations as possible without being blocked. The tester can also use the detailed error messages that disclose whether the username or password entered is incorrect, which can help narrow down the search space and reduce the number of guesses needed. For example, if the tester enters a wrong username and a wrong password, and the application responds with “Invalid username”, the tester can eliminate that username from the list of candidates and focus on finding the correct one. Similarly, if the tester enters a correct username and a wrong password, and the application responds with “Invalid password”, the tester can confirm that username and focus on finding the correct password. By using automated tools or scripts, the tester can perform a Brute Force attack faster and more efficiently.

The other options are not as effective or feasible as option A for the following reasons:

B. The tester could exploit a potential SQL Injection vulnerability to manipulate the application’s database: This option is not feasible because there is no indication that the application is vulnerable to SQL Injection, which is a web security vulnerability that allows an attacker to interfere with the queries that an application makes to its database2. The application uses form-based authentication, which does not necessarily involve SQL queries, and the error messages do not reveal any SQL syntax or structure. Moreover, even if the application was vulnerable to SQL Injection, the tester would need to craft a malicious SQL query that can bypass the authentication mechanism and grant access to the application, which may not be possible or easy depending on the database design and configuration.

C. The tester could launch a Cross-Site Scripting (XSS) attack to steal authenticated session cookies, potentially bypassing the clickjacking protection: This option is not effective because there is no evidence that the application is vulnerable to XSS, which is a web security vulnerability that allows an attacker to compromise the interactions that users have with a vulnerable application by injecting malicious scripts3. The application uses HTTP headers to prevent clickjacking attacks, which are a type of attack that tricks a user into clicking on a hidden or disguised element on a web page4. However, this does not imply that the application is vulnerable to XSS, which requires a different type of injection point and payload. Moreover, even if the application was vulnerable to XSS, the tester would need to find a way to deliver the malicious script to a legitimate user who is already authenticated, and then capture the stolen session cookies from the user’s browser, which may not be feasible or easy depending on the application’s design and security measures.

D. The tester could execute a Man-in-the-Middle (MitM) attack to intercept and modify the HTTP headers for a Clickjacking attack: This option is not feasible because a MitM attack is a type of attack that requires the attacker to insert themselves between two parties who believe that they are directly communicating with each other, and then relay or alter the communications between them5. In this scenario, the tester would need to intercept the HTTP traffic between the user and the application, and then modify the HTTP headers to remove or weaken the clickjacking protection. However, this would require the tester to have access to the network infrastructure or the user’s device, which may not be possible or easy depending on the network security and encryption. Moreover, even if the tester could perform a MitM attack, the tester would still need to trick the user into clicking on a malicious element on a web page, which may not be possible or easy depending on the user’s awareness and behavior.

References:

1: What is a Brute Force Attack? | Definition, Types & How It Works - Fortinet

2: What is SQL Injection? Tutorial & Examples | Web Security Academy

3: Cross Site Scripting (XSS) | OWASP Foundation

4: What is Clickjacking? | Definition, Types & Examples - Fortinet

5: Man-in-the-middle attack - Wikipedia

File created by Bash, a Unix-based shell program commonly used on Mac OS X and Linux operating systems; stores a history of user commands entered at the command prompt; used for viewing old commands that are executed.BASH_HISTORY files are hidden files with no filename prefix. They always use the filename .bash_history.NOTE: Bash is that the shell program employed by Apple Terminal.Our goal is to assist you understand what a file with a *.bash_history suffix is and the way to open it.The Bash History file type, file format description, and Mac and Linux programs listed on this page are individually researched and verified by the FileInfo team. we attempt for 100% accuracy and only publish information about file formats that we’ve tested and validated.

Data encryption with AES-128 is likely to provide the best balance of security and performance in this scenario. This option works as follows:

AES-128 is a symmetric encryption algorithm that uses a 128-bit key to encrypt and decrypt data. AES-128 is one of the most widely used and trusted encryption algorithms, and it is considered secure against classical and quantum attacks, as long as the key is not compromised. AES-128 has a time complexity of O(n), which means that the encryption and decryption time is proportional to the size of the data. AES-128 is also fast and efficient, as it can process 16 bytes of data in each round, and it requires only 10 rounds to complete the encryption or decryption12.

RSA-4000 is an asymmetric encryption algorithm that uses a 4000-bit key pair to encrypt and decrypt data. RSA-4000 is used for key exchange, which means that it is used to securely share the AES-128 key between the sender and the receiver. RSA-4000 has a time complexity of O(n*2), which means that the key generation, encryption, and decryption time is proportional to the square of the size of the key. RSA-4000 is also slow and resource-intensive, as it involves large number arithmetic and modular exponentiation operations. RSA-4000 is considered secure against classical attacks, but it is vulnerable to quantum attacks, especially if the attacker has access to a quantum computer with sufficient resources to run Shor’s algorithm, which can factor large numbers in polynomial time34.

The attacker’s quantum algorithm has a time complexity of O((log n)*2), which means that the cracking time is proportional to the square of the logarithm of the size of the key. This implies that the attacker can crack RSA-4000 much faster than a classical computer, as the logarithm function grows much slower than the linear or quadratic function. For example, if a classical computer takes 10^12 years to crack RSA-4000, a quantum computer with the attacker’s algorithm could do it in about 10^4 years, which is still a long time, but not impossible5.

Therefore, data encryption with AES-128 is likely to provide the best balance of security and performance in this scenario, because:

AES-128 is secure and fast, and it can encrypt large amounts of data efficiently.

RSA-4000 is slow and vulnerable, but it is only used for key exchange, which involves a small amount of data and a one-time operation.

The attacker’s quantum algorithm is powerful, but it is not practical, as it requires a quantum computer with a large number of qubits and a long coherence time, which are not available yet.

The other options are not as balanced as option C for the following reasons:

A. Data encryption with 3DES using a 168-bit key: This option offers high security but slower performance due to 3DES’s inherent inefficiencies. 3DES is a symmetric encryption algorithm that uses a 168-bit key to encrypt and decrypt data. 3DES is a variant of DES, which is an older and weaker encryption algorithm that uses a 56-bit key. 3DES applies DES three times with different keys to increase the security, but this also increases the complexity and reduces the speed. 3DES has a time complexity of O(n), but it is much slower than AES, as it can process only 8 bytes of data in each round, and it requires 48 rounds to complete the encryption or decryption. 3DES is considered secure against classical and quantum attacks, but it is not recommended for new applications, as it is outdated and inefficient67.

B. Data encryption with Blowfish using a 448-bit key: This option offers high security but potential compatibility issues due to Blowfish’s less widespread use. Blowfish is a symmetric encryption algorithm that uses a variable key size, up to 448 bits, to encrypt and decrypt data. Blowfish is fast and secure, and it has a time complexity of O(n), as it can process 8 bytes of data in each round, and it requires 16 rounds to complete the encryption or decryption. Blowfish is considered secure against classical and quantum attacks, but it is not as popular or standardized as AES, and it may have compatibility issues with some applications or platforms89.

D. Data encryption with AES-256: This option provides high security with better performance than 3DES, but not as fast as other AES key sizes. AES-256 is a symmetric encryption algorithm that uses a 256-bit key to encrypt and decrypt data. AES-256 is a variant of AES, which is the most widely used and trusted encryption algorithm. AES-256 has a time complexity of O(n), and it can process 16 bytes of data in each round, but it requires 14 rounds to complete the encryption or decryption, which is more than AES-128 or AES-192. AES-256 is considered secure against classical and quantum attacks, but it is not as fast as other AES key sizes, and it may not be necessary for most applications, as AES-128 or AES-192 are already secure enough12.

References:

1: Advanced Encryption Standard - Wikipedia

2: AES Encryption: What It Is and How It Works | Kaspersky

3: RSA (cryptosystem) - Wikipedia

4: RSA Encryption: What It Is and How It Works | Kaspersky

5: Shor’s algorithm - Wikipedia

6: Triple DES - Wikipedia

7: 3DES Encryption: What It Is and How It Works | Kaspersky

8: Blowfish (cipher) - Wikipedia

9: Blowfish Encryption: What It Is and How It Works | Kaspersky

https://www.offensive-security.com/metasploit-unleashed/msfencode/

One of the best ways to avoid being stopped by antivirus software is to encode our payload with msfencode. Msfencode is a useful tool that alters the code in an executable so that it looks different to antivirus software but will still run the same way. Much as the binary attachment in email is encoded in Base64, msfencode encodes the original executable in a new binary. Then, when the executable is run, msfencode decodes the original code into memory and exe-cutes it.

The Common Vulnerability Scoring System (CVSS) is a method used to supply a qualitative measure of severity for a vulnerability. CVSS consists of three metric groups: Base, Temporal, and Environmental. The Base metrics produce a score ranging from 0 to 10, which can then be modified by scoring the Temporal and Environmental metrics. A vector string represents the values of all the metrics as a block of text1

The Base metrics measure the intrinsic characteristics of a vulnerability, such as the attack vector, the attack complexity, the required privileges, the user interaction, the scope, and the impact on confidentiality, integrity, and availability. The Base score reflects the severity of a vulnerability assuming that there is no temporal information or context available1

The Temporal metrics measure the characteristics of a vulnerability that change over time, such as the exploit code maturity, the remediation level, and the report confidence. The Temporal score reflects the current state of a vulnerability and its likelihood of being exploited1

The Environmental metrics measure the characteristics of a vulnerability that depend on a specific implementation or environment, such as the security requirements, the modified base metrics, and the collateral damage potential. The Environmental score reflects the impact of a vulnerability on a particular organization or system1

In this scenario, the vulnerability has a Base score of 7, a Temporal score of 8, and an Environmental score of 5. This means that:

The vulnerability has a high severity based on its intrinsic characteristics, such as the attack vector, the attack complexity, the required privileges, the user interaction, the scope, and the impact on confidentiality, integrity, and availability. A Base score of 7 corresponds to a high severity rating according to the CVSS v3.0 specification1

The vulnerability has an increasing likelihood of exploitability over time based on its current state, such as the exploit code maturity, the remediation level, and the report confidence. A Temporal score of 8 is higher than the Base score of 7, which indicates that the vulnerability is more likely to be exploited as time passes1

The vulnerability has a medium impact on the specific environment or implementation based on the security requirements, the modified base metrics, and the collateral damage potential. An Environmental score of 5 is lower than the Base score of 7, which indicates that the vulnerability is less impactful in the particular context of the organization or system1

Therefore, the statement that best describes this scenario is: The vulnerability has an overall high severity, the likelihood of exploitability is increasing over time, and it has a medium impact in their specific environment.

References:

NVD - Vulnerability Metrics

document.write(); (Cookie and session ID theft)

https://www.softwaretestinghelp.com/cross-site-scripting-xss-attack-test/

As seen in the indicated question, cookies are escaped and sent to script to variable ‘cookie’. If the malicious user would inject this script into the website’s code, then it will be executed in the user’s browser and cookies will be sent to the malicious user.

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

The Metasploit Project is a computer security project that provides information about security vulnerabilities and aids in penetration testing and IDS signature development. It is owned by Boston, Massachusetts-based security company Rapid7.

Its best-known sub-project is the open-source Metasploit Framework, a tool for developing and executing exploit code against a remote target machine. Other important sub-projects include the Opcode Database, shellcode archive and related research.

The Metasploit Project includes anti-forensic and evasion tools, some of which are built into the Metasploit Framework. Metasploit is pre-installed in the Kali Linux operating system.

The basic steps for exploiting a system using the Framework include.

1. Optionally checking whether the intended target system is vulnerable to an exploit.

2. Choosing and configuring an exploit (code that enters a target system by taking advantage of one of its bugs; about 900 different exploits for Windows, Unix/Linux and macOS systems are included).

3. Choosing and configuring a payload (code that will be executed on the target system upon successful entry; for instance, a remote shell or a VNC server). Metasploit often recommends a payload that should work.

4. Choosing the encoding technique so that hexadecimal opcodes known as "bad characters" are removed from the payload, these characters will cause the exploit to fail.

5. Executing the exploit.

This modular approach – allowing the combination of any exploit with any payload – is the major advantage of the Framework. It facilitates the tasks of attackers, exploit writers and payload writers.