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A cavity virus is a relatively uncommon type of virus that copies itself into unused spaces in files, thus spreading without affecting the file size of whatever it is infecting. They are sometimes also called “space filler” viruses. Many files have empty spaces that are normally ignored when it comes to executing the file they’re part of. The presence of these spaces isn’t a problem – unless they are infected by a virus, of course.

Since no change is made to the file size, it’s impossible to know whether a file has been altered purely by checking its properties – instead, you would have to compare it to a previous, uninfected version to be sure. Space fillers have been around since 1998 and are reasonably difficult to spot. There were several very successful virus waves around the Windows 95/98 days.

How does it work?

In order to infect files, a space filler first needs to find a file that has empty space in it. So, it needs to scan for empty spaces. When it finds empty space in a file somewhere, it will copy itself in, filling the space without making the file larger. That makes it difficult to detect by anti-virus programs.

As long as the virus keeps finding spaces big enough to copy itself into, it will continue to do so – if it finds nowhere or it’s already infected all possible options, then it may sit idle until triggered or simply continue its scanning until a new file suitable for it appears. As such, it will consume processing power in the background which can slow down other things.

This technique relies on primitive antivirus techniques that almost exclusively look for signatures of known viruses. By infecting an existing file, the resulting infected signature is unique to the combination of file and virus.

A real example

In 1998 a virus called CIH, demonstrated this functionality. It was nicknamed Chernobyl because its payload was incidentally set to trigger on the date of the Chernobyl disaster more than a decade earlier. The virus specifically targeted gaps in Portable Execution or PE files. It split its code to fit neatly in those gaps and inserted a table at the top of the file to track the locations of its code so it could run properly.

CIH would then, on the trigger date, overwrite the first megabyte of storage with zeroes. This generally destroyed the partition table or master boot record. Losing that makes it appear as if the entire drive has been wiped. The data, however, was recoverable. The virus would also attempt to wipe the BIOS chip. This was only successful on some devices and not others. On devices with a wiped BIOS chip, either the chip needed reprogramming or replacing. The other alternative was to get a new computer.

All told the CIH virus was estimated to have caused US$1 billion in damages and to have infected 60 million computers around the world. The virus was written by Chén Yíngháo, a student at Tatung University in Taiwan. Chén claimed that the virus was written as a challenge against the overly bold efficiency claims made by antivirus developers. It was then released by classmates, though it’s unclear if this was deliberate or accidental. Chén apologised to the university and published an antivirus for CIH. No charges were ever brought because at the time, Taiwan lacked computer crime legislation and no victims came forward with a lawsuit.

Prevention Conclusion

A cavity virus, also known as a space filler virus, is a type of malware that hides itself in gaps in other files. This technique makes it really hard to detect with basic file signature checks. It also avoids adjusting the infected file’s size, making it even harder to detect. The most well-known example, CIH, used this technique to great effect. It split its code across as many gaps as it needed and inserted a table at the top of the file to track the location of its code. Modern antivirus techniques are capable of identifying this sort of virus, so it is not commonly used.

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What Is A Corporation Business?

Every company faces competition from the marketplace. We have to plan in a manner so it can beat the competition and reach success. Planning/strategy is an essential point that followed by businesses to attain organizational goals.

Business Strategy always needs a portfolio approach across the globe to find out more & return to make the maximum profits. To be able to develop a business plan, companies must take a look at, how they affect one another and finalize the way to optimize human capital, procedures, and governance.

Almost, every company association follow these 2 plans for their set up

1. Corporate strategy

2. Business plan

A company can only succeed if it considers each of the 2 levels of plan

So, let’s have a Brief on Corporate strategy & Business Strategy

Corporate plan

A corporation business plan is basically developed to give instructions to the company for accomplishing their long-term goals. A corporate plan is designed in a manner to achieve goals and focus on the actions of their organization.

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Business plan

Whether large scale or small business organization may have numerous business units or sections that are distributed over different markets. A strategic business unit could identify the merchandising branch & the goals might be different from another unit.

In the level of company units, strategy formula is connected to the way the company competes with other companies in the sector. The plan developed at this point might be changed according to the available need.

What is a Corporation?

A Corporation or Corporation business is a legal identity & credit by individual or company can be produced by one shareholder or maybe from different shareholders but the ultimate goal would be to earn the profit.

A corporate could be shaped on both either for-profit or even a non-profit. For-profit basis, the organization performs well to create revenues and supply a return for its investors, depending on their percentage of ownership in the company.

Not-for-profit entities function, that can be committed to a specific social cause such as educational, spiritual, scientific, or research functions. Non-profit organizations use their earnings to further their own intentions.

The 3 different C used in corporations are- 1. C Corporation

C Corporation is the most typical kind of incorporation among companies and contains all the attributes of the corporation. In this Owners receives a profit on the individual level.

2. S Corporation

S Corporation is work exactly in the same manner for a C Corporation but differs in owner limit and taxation functions.

An S Corporation is made up of around 100 shareholders and isn’t taxed as independent and the profits/losses are shouldered by the shareholders in their own income tax returns.

3. Non-Profit Corporation There are different ways of the corporate plan, but leaders of associations are concentrate on.

The primary tasks of corporate plans are

The allocation of funds in a company focuses mostly on just two sources

A. Capital

B. People

In a bid to maximize the value of the whole company, leaders need to determine how to allocate the resources to different companies or business units to create more revenue.

Key factors about the allocation of funds are


Identifying core competencies and ensuring that they are well dispersed Throughout the company. They’re needed most and include the maximum value.


Allocating funds across companies so that it earns the Greatest risk-adjusted yield.

Assessing external chances and allocating funding between inner jobs and outside chances

Key factors about the allocation of funds are

Head office

Deciding how much freedom to provide business units

Deciding whether conclusions are made top or bottom-up

Impact on the plan of company units

hierarchical arrangement

how big initiatives and responsibilities will be divided into smaller jobs

Integrating business units and business functions like there are no redundancies

Allowing for the balance between return and risk to existing by dividing responsibilities

Creating centres for excellence

Placing governance structures

Placing reporting arrangements (army/top, matrix coverage

Portfolio Management

Portfolio management determines the way business units match each other, their correlations, & determines where the company will perform what the company will do.

Business corporate associated with portfolio management comprises

Determining what company to maintain or to be from

Specifying the degree of vertical integration that the company ought to have

Managing risk through diversification and reducing the significance of outcomes across companies

Establishing strategic choices by seeding new opportunities which could be significantly invested in if proper

Monitor the competitive landscape and ensure the portfolio is well balanced relative to trends in the Industry

Strategic Tradeoffs

Among the most difficult facets of Corporation business strategy or business strategy is balancing the tradeoffs between risk and return throughout the company. It is important to get a holistic view of all of the businesses combined and make the desirable amounts try to find the risk management and reunite creation are being chased.

Below are the primary factors to Think about for tactical tradeoffs Managing threat

many businesses adopt a copycat plan by considering what other risk-takers have done and it is a really risky strategy that could lead to a market leadership position or complete ruin in one second.

It is essential to be conscious of plans and related risks throughout the company. The amount of autonomy company units have is important in managing this threat

Generating Returns

May higher risk plans make the possibility to get the best return. It’s important to get the proper number of alternatives from the portfolio. These choices can come from your portfolio.


Incentive structures will play a big role and It Might Be necessary to divide the responsibilities of hazard management and reunite creation so that each may be up into the desirable degree.

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Corporation Business Strategy differs than business plan as it concentrates on how to handle assets, risk, and come across a company, instead of looking at competitive benefits.

Leaders are accountable for tactical decision-making need to think about many aspects, such as allocation of resources, organizational design, portfolio management, and tactical tradeoffs.

By optimizing each the above-mentioned aspects, an individual can ideally produce a portfolio of companies that’s more worthy.

What Is A Digital Signature?

Introduction to Digital Signature

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Why do we need Digital Signature?

We need a digital signature because of its following features:

1. Message Authentication 2. Non-Repudiation

As the only sender knows the secret key, i.e. signature key, he is the only one who can create a unique signature on the data. If any problem arises, the receiver can show the evidence of the data and digital signature key to the third party.

3. Data Integrity

It provides data integrity to test the modification in the message. If somehow, the attacker gets access to the message and modifies the data. Verification at the receiver side will fail. This is because the hash value of the modified message and the algorithm’s value will not match. In this case, the receiver can reject the message.

How does it Work?

The user who adopts has a pair of keys – a public key and a private key. These keys are used for the Encryption and decryption process. The private key is used for the encryption, i.e., signing the signature, or we can say that it is the signature key, and the public key is used for the decryption, i.e. verification key.

The user, i.e. the signer, apply the hash function on the data and creates the hash of data.

After that, apply a signature algorithm on both the hash value and the signature key to create the given hash’s digital signature.

Then the signature is appended with data, and both signature and data are sent to the verifier over the network.

Verifier, i.e. receiver, apply verification algorithm and verification key. This process gives value as an output.

Verifier also used the same hash function on the data, which the signer uses to get the hash value.

Then he verifies the hash value and the output, which is generated by an algorithm. Based on the result, the verifier validates it. If both are the same, the digital signature is valid; otherwise, it is invalid.

Suppose user A is a sender and user B is a receiver. A wants to send a message to B. User A takes the plain text and encrypt it using A’s private key and create a ciphertext. Then A transfer the Ciphertext to B over the network. To decrypt the ciphertext, B uses A’s public key and create plain text.

Types of Attacks on Digital Signature

Following are the three types of attacks that are attempted against the digital signature:

Chosen Message Attack: The attacker tricks the genuine user into digitally signing a Message that the user does not normally intend to sign. As a result, the attacker gets a pair of the original message that was signed and the digital signature. using this, the attacker tries to create a new message that she wants a genuine user to sign and uses the previous signature

Known Message Attack: In this type of attack, the attacker obtains some messages that the user sends and a key to create a new fault message and forge of the user.

Key only Attack: In this type of attack, it is assumed that the user name some information public and the attacker try to misuse this public information. Attackers try to create the user. RSA and digital signature.

RSA algorithm is used for performing. Here we will discuss the working of RSA.

The sender uses the SHA1 message-digest algorithm to create an original message digest.

The sender encrypts the message digest using the sender’s private key.

The sender send s the message to the receiver along with the digital signature.

After receiving the message, the receiver uses the same algorithm used by the senders to create the message digest.

The receiver now uses the senders public key to decrypt. The output of this process is the message digest that was created at the sender site.

The receiver compares both message digest, the one which he calculates and the one which the sender calculates. If both are the same, then the receiver accepts the message otherwise rejects the message.

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What Is A Script Kiddie?

The most skilled hackers often end up in groups referred to as APTs or Advanced Persistent Threats. These groups are highly qualified, extremely well-funded, and generally well-motivated to carry out their targeted attacks against chosen victims. Typically, if an APT decides you’re their target, very little can be done to prevent them from achieving their goal. This is because they use their skill sets to develop new and unseen exploits which are extremely difficult to defend against. APTs also prefer to operate stealthily, often allowing their exploits to work unnoticed for a long time.

You get the script kiddie at the opposite end of the skill tree.

What Is a Script Kiddie?

A script kiddie is a pejorative term used to refer to hackers who don’t have the skills to write their own exploits and hacks and are forced to rely on public hacking scripts. The term script kiddie may sometimes be shortened to “skiddie” or even “skid.” “Script” refers to their use of scripts, while kiddie is used to emphasize the child-like skill level and often the aim to look cool. Rather than being able to write their tools, script kiddies have to use scripts written by other, more experienced hackers.

Tip: A “script,” In this case, a ” script ” doesn’t refer to a script like an actor would use. Instead, it relates to a pre-written and ready-to-execute exploit or tool. Often they will be pretty automated by the writer for ease of use. For example, a “script” might launch a denial of service exploit against a chosen server. Another script might search the computer for any databases and automatically copy the database files to the attacker.

A script kiddie also generally doesn’t care to understand or can’t understand how the tools they use work. They are often treated as black boxes. They may understand the information they need to put in, such as a target IP address, and what information they might get back if it succeeds. The difference is that they don’t understand how it’s done and couldn’t replicate the feat manually without the script.

Hackers often use the term pejoratively to refer to any hacker they feel has less skill than themselves or as an insult.

No skills Don’t Mean No Threat

It might seem relatively easy to dismiss the threat of a script kiddie. However, they should not be entirely overlooked. Lacking skills, a script kiddie will often use tools when they’re not appropriate simply because they might work. This can even be broadly automated with bots to widespread spraying of an exploit. While they may not get many successes, they might not be entirely unsuccessful. It’s sort of like the concept of a weapon in the hands of an unskilled fighter. Even if they don’t understand how to use the weapon to its most significant effect, they can still cause some damage.

There are plenty of powerful hacking tools available online. Some of them are paid, while many are free. This can give a script kiddie a broad range of tools to try. If they have a specific target they want to try to hack, they may unleash their entire arsenal of scripts to see what works, if anything.

They may also be familiar enough with some of the basics to research specific tools that work against the target. Even this level of skill certainly isn’t guaranteed, though. For example, many script kiddies who don’t know what they’re doing will launch an exploit for an Apache web server vulnerability, even if the web server actively identifies itself as running Nginx rather than Apache. With just a bit of skill and awareness, a script kiddie can locate and use that information. For example, they may be able to identify that a website uses WordPress and search specifically for WordPress exploits.

Countering Script Kiddies

Minimizing the threat from script kiddies is relatively easy. They tend to use published exploits, which naturally work on known vulnerabilities. To prevent these from working, ensure that all software is updated.

Logging and reviewing logs make it pretty easy to identify script kiddies. Their tendency to either spray and pray with a single exploit against a broad range of targets or to fire all their scripts at a single target makes them very unsubtle. Both approaches can be countered by monitoring logs and looking for requests that appear to be malicious. Then it is relatively simple to add their IP address to a block list.

From a hacker perspective, they can also make it more difficult for script kiddies to use their tools. For example, requiring a specific command line flag to run that’s only documented in the code or by not fully automating processes.


What Is A Sim Card Used For?

Just about every cellular telephone in existence today makes use of a SIM card. “SIM” is short for Subscriber Identity Module. Without it, you can’t make or receive phone calls. You also can’t use any internet data over a cellular connection.

You probably already knew this, but why is your phone so useless without this small piece of metal and plastic? Just what is a SIM card actually used for?

Table of Contents

What a SIM Card Looks Like

A SIM Card is pretty easy to identify. It’s a plastic card with a distinct set of metal contacts. Inside the SIM card you’ll find an integrated circuit, which communicates with the phone through the aforementioned metal contacts.

SIM cards come in a variety of shapes and sizes. In fact, there are four sizes in total. The largest is known as “full-size” and is effectively obsolete. Measuring 3.37 in by 2.125 in, full-size SIM cards were basically the size of smart access cards.

The reason for this is quite interesting. At the outset of mobile phone technology, multiple people would share a single phone. The idea was that you would insert your enormous SIM card into the phone when you wanted to use it. Since the card would spend more time in your wallet than in a phone, the large plastic body made perfect sense.

These days most SIM cards you’ll buy have all three of the common sizes, with pieces of the plastic body breaking away until you reach the size you want. The Mini-SIM size is pretty uncommon these days and is mostly used in legacy devices or low-cost devices based on older designs.  

The Micro-SIM size is very popular and most mainstream phones use this. The Nano-SIM size eliminates virtually all plastic body around the SIM contacts and is essentially the standard for flagship and mid-high-end smartphones, where internal space is at an extreme premium. SIM cards are physically keyed to make it impossible to insert them the wrong way around. 

Here’s a tip: don’t throw away the Mini- and Micro-SIM frames when you get a new SIM card. If you ever need to move the SIM to another phone you may still need them!

What Does a SIM Card Do?

The cellular network owned by your service provider is just that –  a network. They need to control who has access to that network both for security reasons and to make the whole thing work!

So what is a SIM card? Your SIM card is an access card. It contains your credentials. So in that sense it’s like a card that stores your username and password. You “log in” to the cellular network with the SIM card. Your phone number is your unique network identity. 

No matter where you go, as long as you are within range of a cellular tower belonging to your service provider, you can be reached and reach others.

What’s Stored On a SIM?

The SIM card has information on it that the network needs to authenticate your account. One of these is the ICCID or Integrated Circuit Card Identifier. This is a number that’s unique to that specific physical SIM card.

The next important bit of data on the SIM is known as the authentication key. This is a cryptographic key used to sign data sent to the cellular network. They key is run through a cryptographic function and then compared to another calculation done with a copy of the key stored in the carrier’s database. If they match, you’re let onto the network.

The SIM also has memory on it, that you can use to store your contacts and text messages. This is pretty limited however, with most SIMs sporting between 64k and 256k of space. These days most people are better off storing their contacts on the phone’s own memory, along with a backup using something like iCloud or their Google account.

Contract and Prepaid SIM Cards

There are generally two models cellular providers use to sell their services to customers. You can sign a fixed contract agreement, or you can be a prepaid customer.

In both cases, you’ll get a SIM card. The cards themselves are no different from each other. Rather, it’s how the provider handles the account that sets them apart. You can buy prepaid SIM cards off the shelf. Although in many countries you must register the purchase, using government ID and proof of residence.

Contract SIM cards are allocated data, talk time and other resources according to your contract. Overages are added to your bill and at the end of the billing cycle the money gets deducted from your account. With prepaid cards, you’ll usually load a monetary amount onto the SIM or otherwise purchase talk time or mobile data upfront.

Depending on where you live, certain contract handsets may be locked to SIM cards only from that provider. Often this is a way to get a phone for a substantial discount, but if you ever need to use another SIM card, perhaps when travelling, you’ll find that it doesn’t work! To avoid that sort of situation, be sure to look for phones sold as “unlocked”.

Switching SIM Cards

Taking a SIM from one phone and moving it to another is pretty painless. Given that both phones use the same SIM card size. If the other phone uses a larger size, you’ll have to use an adapter to make it fit the larger slot. If the SIM card you want to use is too large for the target phone, you have two choices.

The first is to cut the SIM down to size. Some people are brave enough to do this using nothing but a pair of scissors and some sort of template. If you accidentally cut into the circuity of the SIM card, it’s game over and you’ll need a new one. The safest way to do this is by using a dedicated SIM cutting tool. Even then, you run the risk of destroying the card, so take this route only at your own risk.

The other option is to switch SIM cards.  Of course, if you just went out and bought a new SIM card, it would have a different phone number associated with it! Each service provider may have a different procedure to move your phone number from one SIM to another.

In general however, it should simply take a phone call and verification of your identity. If the provider has physical stores, you should even have the option of going in for a new SIM, with your old one disabled.

These days it’s popular to use text messages sent to specific SIM cards as a form of two-factor authentication. So now we have something known as SIM-swap fraud. Where criminals find ways to have your phone number transferred to a SIM they control. SIM duplication is another method. It’s certainly something to watch out for.

Life After SIM Cards

SIM cards, at least discrete SIM cards, aren’t really necessary anymore. We are already seeing the rise of the eSIM or embedded SIM card. This is a SIM card built directly into the phone. This card is programmable, which means you can easily change providers or use multiple providers at once.

In some countries, “dual-SIM” phones have been very popular. With these you could have two phone numbers, one for personal use, for example. You could also have a dedicated data SIM card, perhaps with better rates.

eSIMs make this redundant and turns access and authentication into something similar to fixed-line broadband usage. Where you simply enter a username and password to access a given service provider.

Few current phones have embedded SIM cards at the time of writing, but that’s set to change as the industry adopts this new standard. You next phone might very well have no place to put a SIM card at all, which would be the end of an era, but certainly a move for the better.

What Is A Chief Risk Officer (Cro)?

CROs report to the board and the CEO on various issues, including insurance, IT security, financial audits, internal audits, global business variables, fraud prevention, and other internal corporate matters.

The CRO must implement operational risk management and mitigation processes to prevent losses caused by insufficient or failed procedures, systems or policies.

The operational risk management process includes disaster recovery and business continuity planning, developing information security policies and managing regulatory compliance data.

There are four broad risk categories

CROs typically focus on the following four broad risk categories:

Compliance risk is related to an organisation’s ability to identify and meet its responsibilities under laws, rules, and regulations.

Risks relating to operations, including business interruptions, labour issues, technology problems, and vendor turnover.

The risk of reputational damage, which can harm an organisation’s reputation, recognition, standing, and value with its employees, shareholders, customers, and the general public; and

Strategic risk entails any risk that may impact an organisation’s ability to execute its strategy.

CRO roles and responsibilities

In general, the CRO oversees a company’s risk management efforts, including risk identification and mitigation. One of the biggest current concerns for CROs is cybersecurity.

Information technology poses risks because it is essential to business processes. Increasingly, CROs are involved in evaluating and mitigating the risks posed by hackers and data breaches. As a critical part of the CRO’s job, the information protection strategy and risk assurance efforts have evolved, as have the abilities for identifying vulnerabilities and threats to a company’s data.

Other CRO responsibilities include:

Mitigating the company’s primary threats by developing risk maps and strategic action plans;

Keeping track of risk mitigation efforts;

Producing and distributing risk analyses and progress reports to company executives, board members and employees;

Including strategic risk management priorities in the company’s overall strategic plan;

Planning and executing information assurance strategies to protect against and manage risks associated with the use, storage and transmission of data and information;

Assessing how errors made by employees or system failures might disrupt business processes, then developing strategies to minimise exposure to those risks;

Identifying and quantifying the amount of risk that the company should be taking – this is known as risk appetite;

Budgeting and overseeing risk management and mitigation projects;

Keeping stakeholders and board members informed about the business’s risk profile and assessments.

Furthermore, CROs may conduct due diligence and risk assessments on behalf of the company during a merger or acquisition. For example, a CRO may examine the risks surrounding a potential acquisition target and assess whether its risk management frameworks and processes are reliable.

Responsibilities vary by sector

The chief risk officer’s responsibilities and qualifications vary by sector and organisation size. The CRO of a bank, for example, should be familiar with financial compliance requirements, fraud prevention, and potential threats to monetary transactions.


In most cases, CROs have postgraduate education, often a master’s degree in business administration. Generally, they have spent many years working in accounting, economics, legal, or actuarial fields and will have training in risk management.

Since cybersecurity and online risk mitigation have become crucial for corporate success, some CROs have also worked in the IT or cybersecurity industries.

Typical CROs come from backgrounds that include auditing, accounting, financial analysis, loss prevention, operations management, risk management, and security analysis.

As well as having experience working with executives, conducting internal audits, and reporting to a board, the ideal CRO candidate will be experienced in managing change.


For a CRO to effectively identify and assess risks and develop mitigation strategies to reduce those risks, they should possess the following skills:

Skills in quantitative and analytical calculations;

Knowledge of finance and accounting to understand how various risks impact the company’s budget and revenue;

The ability to collaborate with, influence, and educate employees and fellow executives about risk-related matters;

An understanding of systems, networks, IT infrastructure and cyber threats related to digital and corporate technology;

Why is a CRO needed?

Almost all organisations face threats and risks that harm their operations and stakeholders. Risks may even threaten the life of the organisation. Risks are also constantly evolving and getting more complex. This is especially true for large, global or publicly traded companies. A CRO with education and experience in identifying, assessing, and mitigating such risks is essential for these organisations.

Who does the chief risk officer report to?

The chief risk officer reports to the CEO and board of directors.

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