# Chapter a few: Core Security Principles and Concepts
Ahead of diving further into threats and defenses, it's essential to be able to establish the basic principles that underlie application security. These core concepts are the compass through which security professionals navigate decisions and trade-offs. They help answer why certain adjustments are necessary and what goals many of us are trying in order to achieve. Several foundational models and concepts slowly move the design plus evaluation of safeguarded systems, the nearly all famous being the particular CIA triad and associated security principles.
## The CIA Triad – Privacy, Integrity, Availability
In the middle of information protection (including application security) are three major goals:
1. **Confidentiality** – Preventing illegal use of information. Inside simple terms, preserving secrets secret. Only those who will be authorized (have the particular right credentials or permissions) should end up being able to watch or use delicate data. According to be able to NIST, confidentiality implies "preserving authorized limitations on access in addition to disclosure, including means that for protecting individual privacy and amazing information"
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. Breaches regarding confidentiality include phenomena like data leakages, password disclosure, or even an attacker looking at someone else's email messages. A real-world example of this is an SQL injection attack that will dumps all consumer records from a database: data that will should have been secret is subjected to the particular attacker. The opposite associated with confidentiality is disclosure
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– when information is revealed to these not authorized to see it.
two. **Integrity** – Safeguarding data and methods from unauthorized adjustment. Integrity means that will information remains correct and trustworthy, and even that system features are not interfered with. For example, in case a banking application displays your account balance, integrity steps ensure that the attacker hasn't illicitly altered that equilibrium either in passage or in typically the database. Integrity can certainly be compromised by simply attacks like tampering (e. g., changing values in a WEB ADDRESS to access a person else's data) or by faulty program code that corrupts files. A classic system to make sure integrity is the usage of cryptographic hashes or autographs – if a record or message is altered, its signature bank will no extended verify. The contrary of integrity is often termed alteration – data becoming modified or dangerous without authorization
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3. **Availability** – Making sure systems and data are accessible as needed. Even if information is kept key and unmodified, it's of little work with in the event the application is down or inaccessible. Availability means that will authorized users can reliably access typically the application and the functions in a timely manner. Dangers to availability incorporate DoS (Denial of Service) attacks, exactly where attackers flood the server with targeted traffic or exploit a vulnerability to impact the machine, making that unavailable to legit users. Hardware problems, network outages, or even even design issues that can't handle top loads are likewise availability risks. The particular opposite of accessibility is often referred to as destruction or refusal – data or perhaps services are ruined or withheld
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. Typically the Morris Worm's influence in 1988 has been a stark prompt of the significance of availability: it didn't steal or modify data, but by causing systems crash or slow (denying service), it caused major damage
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These three – confidentiality, integrity, and availability – are sometimes named the "CIA triad" and are considered the three pillars involving security. Depending upon the context, a great application might prioritize one over the others (for illustration, a public news website primarily cares that it's available as well as its content ethics is maintained, privacy is much less of the issue since the content material is public; alternatively, a messaging application might put discretion at the leading of its list). But a secure application ideally have to enforce all in order to an appropriate degree. Many security regulates can be realized as addressing one particular or more of these pillars: encryption works with confidentiality (by striving data so only authorized can read it), checksums and audit logs help integrity, and redundancy or failover devices support availability.
## The DAD Triad (Opposites of CIA)
Sometimes it's helpful to remember the particular flip side of the CIA triad, often called FATHER:
- **Disclosure** – Unauthorized access to be able to information (breach involving confidentiality).
- **Alteration** – Unauthorized transform of information (breach involving integrity).
- **Destruction/Denial** – Unauthorized break down of information or denial of service (breach of availability).
Safety measures efforts aim to prevent DAD results and uphold CIA. A single attack can involve several of these factors. By way of example, a ransomware attack might the two disclose data (if the attacker shop lifts a copy) and even deny availability (by encrypting the victim's copy, locking these people out). A net exploit might alter data inside a repository and thereby break the rules of integrity, etc.
## Authentication, Authorization, and Accountability (AAA)
Inside securing applications, especially multi-user systems, we rely on extra fundamental concepts often referred to as AAA:
1. **Authentication** – Verifying the identity of an user or method. When you log throughout with an account information (or more safely with multi-factor authentication), the system is definitely authenticating you – making certain you usually are who you claim to be. Authentication answers the issue: Which are you? Frequent methods include security passwords, biometric scans, cryptographic keys, or tokens. A core principle is that authentication need to be strong enough in order to thwart impersonation. Weakened authentication (like effortlessly guessable passwords or even no authentication high should be) is really a frequent cause of breaches.
2. **Authorization** – Once id is made, authorization adjustments what actions or data the authenticated entity is granted to access. It answers: What are a person allowed to carry out? For example, after you log in, a good online banking software will authorize you to see your individual account details although not someone else's. Authorization typically requires defining roles or even permissions. A typical weakness, Broken Access Handle, occurs when these types of checks fail – say, an attacker finds that by changing a list IDENTITY in an WEB LINK they can watch another user's data as the application isn't properly verifying their particular authorization. In reality, Broken Access Handle was referred to as the number one website application risk in the 2021 OWASP Top 10, found in 94% of software tested
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, illustrating how pervasive and important suitable authorization is.
three or more. **Accountability** (and Auditing) – This appertains to the ability to trace actions in the particular system towards the responsible entity, which will means having proper logging and audit hiking trails. If something will go wrong or shady activity is diagnosed, we need in order to know who would what. Accountability is usually achieved through signing of user steps, and by having tamper-evident records. It works hand-in-hand with authentication (you can only hold someone responsible if you know which consideration was performing a good action) and together with integrity (logs by themselves must be guarded from alteration). Inside application security, establishing good logging plus monitoring is important for both detecting incidents and performing forensic analysis after an incident. Since we'll discuss inside of a later section, insufficient logging plus monitoring enables breaches to go unknown – OWASP lists this as another top ten issue, writing that without correct logs, organizations may well fail to notice an attack until it's far too late
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Sometimes you'll notice an expanded phrase like IAAA (Identification, Authentication, Authorization, Accountability) which just breaks out identification (the claim of identification, e. g. getting into username, before actual authentication via password) as a distinct step. But the particular core ideas remain the same. A safeguarded application typically enforces strong authentication, strict authorization checks with regard to every request, and even maintains logs for accountability.
## Rule of Least Privilege
One of typically the most important design principles in safety measures is to offer each user or component the lowest privileges necessary to perform its operate, without more. This particular is the rule of least freedom. In practice, this means if an application has multiple roles (say admin versus regular user), the regular user company accounts should have simply no capability to perform admin-only actions. If the web application demands to access the database, the database account it uses needs to have permissions only for the particular desks and operations required – one example is, in the event that the app by no means needs to erase data, the DB account shouldn't even have the ERASE privilege. By restricting privileges, even if an attacker compromises a good user account or perhaps a component, destruction is contained.
A bare example of not necessarily following least benefit was the Capital One breach associated with 2019: a misconfigured cloud permission allowed a compromised part (a web software firewall) to retrieve all data by an S3 storage bucket, whereas in the event that that component experienced been limited to only a few data, the breach impact would have been a long way smaller
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. Least privilege in addition applies at the program code level: if the module or microservice doesn't need certain entry, it shouldn't have got it. Modern box orchestration and foriegn IAM systems help it become easier to implement granular privileges, yet it requires innovative design.
## Defense in Depth
This particular principle suggests that will security should be implemented in overlapping layers, so that if one layer falls flat, others still offer protection. Put simply, don't rely on any single security handle; assume it can be bypassed, plus have additional mitigations in place. Intended for an application, protection in depth may possibly mean: you validate inputs on the particular client side intended for usability, but a person also validate these people on the server side (in case the attacker bypasses the customer check). You safe the database at the rear of an internal firewall, however you also create code that bank checks user permissions ahead of queries (assuming an attacker might breach the network). When using encryption, you might encrypt very sensitive data inside the databases, but also enforce access controls on the application layer and monitor for strange query patterns. Protection in depth is like the levels of an red onion – an assailant who gets through one layer should immediately face one other. This approach counter tops the reality that no single defense is foolproof.
For example, assume an application depends on a website application firewall (WAF) to block SQL injection attempts. Protection in depth would dispute the application should still use safe coding practices (like parameterized queries) to sanitize inputs, in case the WAF does not show for a novel assault. A real scenario highlighting this was basically the case of certain web shells or injection attacks that will were not recognized by security filtration – the internal application controls then served as the particular final backstop.
## Secure by Style and design and Secure by simply Default
These connected principles emphasize producing security a fundamental consideration from the particular start of style, and choosing risk-free defaults. "Secure by design" means you intend the system structure with security inside mind – regarding instance, segregating very sensitive components, using confirmed frameworks, and thinking of how each style decision could expose risk. "Secure simply by default" means when the system is used, it will default to the best settings, requiring deliberate actions to make this less secure (rather than the other method around).
An instance is default accounts policy: a safely designed application may well ship without standard admin password (forcing the installer to set a solid one) – as opposed to using a well-known default security password that users may possibly forget to alter. Historically, many application packages were not secure by default; they'd install with open up permissions or test databases or debug modes active, in case an admin neglected to lock them along, it left slots for attackers. Over time, vendors learned to be able to invert this: today, databases and operating systems often come using secure configurations out there of the package (e. g., remote access disabled, example users removed), in addition to it's up in order to the admin in order to loosen if absolutely needed.
For developers, secure defaults mean choosing safe selection functions by arrears (e. g., standard to parameterized queries, default to output encoding for internet templates, etc. ). It also signifies fail safe – if a part fails, it have to fail in the protected closed state quite than an unsafe open state. For instance, if an authentication service times out there, a secure-by-default approach would deny gain access to (fail closed) instead than allow that.
## Privacy by Design
Idea, tightly related to protection by design, offers gained prominence particularly with laws like GDPR. It means of which applications should become designed not just in end up being secure, but to admiration users' privacy through the ground upwards. In practice, this might involve data minimization (collecting only exactly what is necessary), visibility (users know just what data is collected), and giving customers control of their information. While privacy is usually a distinct domain, it overlaps intensely with security: an individual can't have personal privacy if you can't secure the personalized data you're liable for. A lot of the most severe data breaches (like those at credit rating bureaus, health insurance providers, etc. ) are usually devastating not just as a result of security failure but because that they violate the level of privacy of an incredible number of persons. Thus, modern software security often functions hand in side with privacy considerations.
## Threat Modeling
The practice in secure design is definitely threat modeling – thinking like an attacker to assume what could go wrong. During threat modeling, architects and developers systematically go all the way through the design of a good application to identify potential threats and vulnerabilities. They question questions like: What are we building? What can get wrong? And what will all of us do about it? 1 well-known methodology intended for threat modeling is usually STRIDE, developed at Microsoft, which stands for six categories of threats: Spoofing id, Tampering with files, Repudiation (deniability involving actions), Information disclosure, Denial of assistance, and Elevation of privilege.
By strolling through bias of a system and considering STRIDE dangers, teams can discover dangers that may well not be obvious at first look. For example, think about a simple online salaries application. Threat modeling might reveal that will: an attacker may spoof an employee's identity by questioning the session symbol (so we need strong randomness), could tamper with earnings values via a new vulnerable parameter (so we need type validation and server-side checks), could execute actions and afterwards deny them (so we need good taxation logs to stop repudiation), could take advantage of an information disclosure bug in a great error message to be able to glean sensitive details (so we need user-friendly but obscure errors), might attempt denial of assistance by submitting a huge file or heavy query (so we need charge limiting and resource quotas), or try to elevate privilege by accessing administrator functionality (so we need robust gain access to control checks). By way of this process, safety requirements and countermeasures become much clearer.
Threat modeling is usually ideally done early on in development (during the design phase) so that security is definitely built in from the beginning, aligning with typically the "secure by design" philosophy. It's the evolving practice – modern threat building might also consider misuse cases (how can the system become misused beyond the particular intended threat model) and involve adversarial thinking exercises. We'll see its significance again when talking about specific vulnerabilities and how developers can foresee and prevent them.
## Risk Management
Not every security issue is every bit as critical, and resources are always small. So another principle that permeates app security is risk management. This involves determining the possibilities of a risk and the impact were it to happen. Risk is normally in private considered as a function of these two: a vulnerability that's simple to exploit in addition to would cause extreme damage is higher risk; one that's theoretical or might have minimal effects might be reduce risk. Organizations usually perform risk assessments to prioritize their particular security efforts. For example, an on the internet retailer might decide that this risk associated with credit card fraud (through SQL shot or XSS leading to session hijacking) is incredibly high, and as a result invest heavily in preventing those, although the chance of someone triggering minor defacement upon a less-used webpage might be acknowledged or handled using lower priority.
Frameworks like NIST's or ISO 27001's risk management guidelines help inside systematically evaluating and treating risks – whether by excuse them, accepting all of them, transferring them (insurance), or avoiding them by changing enterprise practices.
One real results of risk supervision in application safety measures is the generation of a menace matrix or threat register where prospective threats are listed along with their severity. This helps drive choices like which insects to fix very first or where to be able to allocate more tests effort. It's also reflected in patch management: if some sort of new vulnerability is announced, teams will certainly assess the danger to their app – is that exposed to of which vulnerability, how severe is it – to make the decision how urgently to utilize the area or workaround.
## Security vs. Simplicity vs. Cost
A discussion of principles wouldn't be total without acknowledging the real-world balancing take action. Security measures can easily introduce friction or perhaps cost. Strong authentication might mean a lot more steps for the customer (like 2FA codes); encryption might impede down performance slightly; extensive logging might raise storage expenses. A principle to follow is to seek balance and proportionality – security should be commensurate with typically the value of what's being protected. Overly burdensome security that frustrates users may be counterproductive (users will dsicover unsafe workarounds, for instance). The skill of application safety measures is finding alternatives that mitigate risks while preserving a new good user experience and reasonable cost. Fortunately, with modern techniques, many safety measures can end up being made quite smooth – for illustration, single sign-on alternatives can improve equally security (fewer passwords) and usability, and even efficient cryptographic your local library make encryption scarcely noticeable with regards to functionality.
In summary, these fundamental principles – CIA, AAA, very least privilege, defense in depth, secure by design/default, privacy considerations, menace modeling, and risk management – form the mental framework with regard to any security-conscious specialist. They will look repeatedly throughout this guide as we examine specific technologies and scenarios. Whenever an individual are unsure about a security decision, coming back to these basics (e. g., "Am I actually protecting confidentiality? Are really we validating integrity? Are we reducing privileges? Can we have multiple layers involving defense? ") may guide you to some more secure outcome.
With one of these principles in mind, we are able to at this point explore the exact risks and vulnerabilities of which plague applications, plus how to defend against them.