Buffer overflow this attack is an anomaly that happens when software writing data to a buffer overflows the buffer's capacity, leading to adjacent memory locations being overwritten. In other words, an excessive amount of information is being passed into a container that doesn't have enough space, which information finishes up replacing data in adjacent containers.
Buffer overflows are often exploited by attackers with a goal of modifying a computer's memory so as to undermine or take hold of program execution.

What's a buffer?
A buffer, or data buffer, is a neighborhood of physical memory storage wont to temporarily store data while it' s being moved from one place to a different . These buffers typically sleep in RAM memory. Computers frequently use buffers to assist improve performance; latest hard drives cash in of buffering to efficiently access data, and lots of online services also use buffers. for instance , buffers are frequently utilized in online video streaming to stop interruption. When a video is streamed, the video player downloads and stores perhaps 20% of the video at a time during a buffer then streams from that buffer. This way, minor drops in connection speed or quick service disruptions won't affect the video stream performance.
Buffers are designed to contain specific amounts of knowledge . Unless the program utilizing the buffer has built-in instructions to discard data when an excessive amount of is shipped to the buffer, the program will overwrite data in memory adjacent to the buffer.
Buffer overflows are often exploited by attackers to corrupt software. Despite being well-understood, buffer overflow attacks are still a serious security problem that torment cyber-security teams. In 2014 a threat referred to as 'heartbleed' exposed many many users to attack due to a buffer overflow vulnerability in SSL software.
How do attackers exploit buffer overflows?
An attacker can deliberately feed a carefully crafted input into a program which will cause the program to undertake and store that input during a buffer that isn't large enough, overwriting portions of memory connected to the buffer space. If the memory layout of the program is well-defined, the attacker can deliberately overwrite areas known to contain executable code. The attacker can then replace this code together with his own executable code, which may drastically change how the program is meant to figure .
For example if the overwritten part in memory contains a pointer (an object that points to a different place in memory) the attacker's code could replace that code with another pointer that points to an exploit payload.
this will transfer control of the entire program over to the
attacker's code.

On Linux and UNIX-like systems, files or directories that begin with a period (.) are considered hidden. These files do not appear by default when a user runs the ls command, unless explicitly instructed to show hidden files using ls -a.
Example:
* File named .hiddenfile will not appear with a simple ls command.
* To view it, use: ls -a
This is commonly used for configuration files (e.g., .bashrc, .profile) and also by attackers or malicious users who want to conceal their scripts or payloads.
Incorrect Options:
* A. Exclamation mark (!) is used in shell history and command expansion, not for hiding files.
* B. Underscore (_) is a valid filename character but does not hide files.
* C. Tilde (~) represents the current user's home directory; not used for hiding.
Reference - CEH v13 Official Courseware:
* Module 06: Malware Threats
* Section: "Tactics to Hide Malware Files in the OS"
* Lab: CEH Engage - Creating and Hiding Files in Linux

The best measure to prevent similar attacks without overly restricting the use of personal devices is to conduct regular cybersecurity awareness training, focusing on phishing attacks. Cybersecurity awareness training is a process of educating and empowering employees on the best practices and behaviors to protect themselves and the organization from cyber threats, such as phishing, malware, ransomware, or data breaches. Cybersecurity awareness training can help the organization mitigate the risk of phishing incidents by providing the following benefits12:
* It can increase the knowledge and skills of employees on how to identify and avoid phishing emails, messages, or links, such as by checking the sender, the subject, the content, the attachments, and the URL of the message, and by verifying the legitimacy and authenticity of the message before responding or clicking.
* It can enhance the attitude and culture of employees on the importance and responsibility of cybersecurity, such as by encouraging them to report any suspicious or malicious activity, to follow the security policies and guidelines, and to seek help or guidance when in doubt or trouble.
* It can reduce the human error and negligence that are often the main causes of phishing incidents, such as by reminding employees to update their devices and applications, to use strong and unique passwords, to enable multi-factor authentication, and to backup their data regularly.
The other options are not as optimal as option D for the following reasons:
* A. Provide employees with corporate-owned devices for work-related tasks: This option is not feasible because it contradicts the BYOD policy, which allows employees to use their personal devices for work- related tasks. Providing employees with corporate-owned devices would require the organization to incur additional costs and resources, such as purchasing, maintaining, and securing the devices, as well as training and supporting the employees on how to use them. Moreover, providing employees with corporate-owned devices would not necessarily prevent phishing incidents, as the devices could still be compromised by phishing emails, messages, or links, unless the organization implements strict security controls and policies on the devices, which may limit the user autonomy and productivity3.
* B. Implement a mobile device management solution that restricts the installation of non-approved applications: This option is not desirable because it violates the user autonomy and privacy under the BYOD policy, which allows employees to use their personal devices for both personal and professional purposes. Implementing a mobile device management solution that restricts the installation of non- approved applications would require the organization to monitor and control the devices of the employees, which may raise legal and ethical issues, such as data ownership, consent, and compliance. Furthermore, implementing a mobile device management solution that restricts the installation of non-approved applications would not completely prevent phishing incidents, as the employees could still receive phishing emails, messages, or links through the approved applications, unless the organization implements strict security controls and policies on the applications, which may affect the user experience and functionality4.
* C. Require all employee devices to use a company-provided VPN for internet access: This option is not sufficient because it does not address the root cause of phishing incidents, which is the human factor.
Requiring all employee devices to use a company-provided VPN for internet access would provide the organization with some benefits, such as encrypting the network traffic, hiding the IP address, and bypassing geo-restrictions. However, requiring all employee devices to use a company-provided VPN for internet access would not prevent phishing incidents, as the employees could still fall victim to phishing emails, messages, or links that lure them to malicious websites or applications, unless the organization implements strict security controls and policies on the VPN, which may affect the network performance and reliability.
References:
1: What is Cybersecurity Awareness Training? | Definition, Benefits & Best Practices | Kaspersky
2: How to Prevent Phishing Attacks with Security Awareness Training | Infosec
3: BYOD vs. Corporate-Owned Devices: Pros and Cons | Bitglass
4: Mobile Device Management (MDM) | OWASP Foundation
5: What is a VPN and why do you need one? Everything you need to know | ZDNet

Triple DES is another mode of DES operation. It takes three 64-bit keys, for an overall key length of 192 bits.
In Stealth, you merely type within the entire 192-bit (24 character) key instead of entering each of the three keys individually. The Triple DES DLL then breaks the user-provided key into three subkeys, padding the keys if necessary in order that they are each 64 bits long. The procedure for encryption is strictly an equivalent as regular DES, but it's repeated 3 times , hence the name Triple DES. the info is encrypted with the primary key, decrypted with the second key, and eventually encrypted again with the third key.
Triple DES runs 3 times slower than DES, but is far safer if used properly. The procedure for decrypting something is that the same because the procedure for encryption, except it's executed in reverse. Like DES, data is encrypted and decrypted in 64-bit chunks. Although the input key for DES is 64 bits long, the particular key employed by DES is merely 56 bits long . the smallest amount significant (right-most) bit in each byte may be a parity , and will be set in order that there are always an odd number of 1s in every byte.
These parity bits are ignored, so only the seven most vital bits of every byte are used, leading to a key length of 56 bits. this suggests that the effective key strength for Triple DES is really 168 bits because each of the three keys contains 8 parity bits that aren't used during the encryption process.
Triple DES Modes
Triple ECB (Electronic Code Book)
* This variant of Triple DES works precisely the same way because the ECB mode of DES.
* this is often the foremost commonly used mode of operation.
Triple CBC (Cipher Block Chaining)
* This method is extremely almost like the quality DES CBC mode.
* like Triple ECB, the effective key length is 168 bits and keys are utilized in an equivalent manner, as described above, but the chaining features of CBC mode also are employed.
* the primary 64-bit key acts because the Initialization Vector to DES.
* Triple ECB is then executed for one 64-bit block of plaintext.
* The resulting ciphertext is then XORed with subsequent plaintext block to be encrypted, and therefore the procedure is repeated.
* This method adds an additional layer of security to Triple DES and is therefore safer than Triple ECB, although it's not used as widely as Triple ECB.

The recommended architecture for secure web application deployment is a multi-tiered setup:
Web server in the DMZ (public-facing)
Application server on the internal network
Database server on the internal network
This design limits the exposure of critical components. Only the web server is exposed to the internet, while application and database servers are shielded by firewalls and only accessible internally.
Reference - CEH v13 Official Study Guide:
Module 10: Hacking Web Servers
Quote:
"Place the web server in the DMZ and keep the application and database servers within the internal network.
This reduces the attack surface and provides layered security."
Incorrect Options Explained:
A). Internal placement makes them inaccessible externally.
C & D. Exposing the database or all servers to the internet introduces significant risk.