# Chapter 3: Core Security Principles and Concepts
Ahead of diving further in to threats and defenses, it's essential to establish the basic principles that underlie application security. These kinds of core concepts are usually the compass through which security professionals find their way decisions and trade-offs. They help answer why certain handles are necessary and what goals we are trying to be able to achieve. Several foundational models and rules slowly move the design and even evaluation of safe systems, the almost all famous being the CIA triad plus associated security rules.
## The CIA Triad – Discretion, Integrity, Availability
At the heart of information protection (including application security) are three principal goals:
1. ** ci/cd pipeline security ** – Preventing unauthorized usage of information. Within simple terms, trying to keep secrets secret. Just those who are usually authorized (have the right credentials or perhaps permissions) should end up being able to see or use sensitive data. According to NIST, confidentiality implies "preserving authorized restrictions on access and even disclosure, including means that for protecting individual privacy and proprietary information"
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. Breaches involving confidentiality include tendency like data leakages, password disclosure, or even an attacker looking at someone else's emails. A real-world illustration is an SQL injection attack that dumps all end user records from the database: data of which should are already secret is encountered with typically the attacker. The opposite of confidentiality is disclosure
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– when info is showed those not authorized to be able to see it.
2. **Integrity** – Guarding data and methods from unauthorized customization. Integrity means that will information remains correct and trustworthy, and that system functions are not interfered with. For example, if the banking program displays your accounts balance, integrity measures ensure that the attacker hasn't illicitly altered that equilibrium either in flow or in typically the database. Integrity can be compromised simply by attacks like tampering (e. g., altering values in an URL to access a person else's data) or by faulty signal that corrupts files. A classic mechanism to assure integrity will be the usage of cryptographic hashes or autographs – if the record or message is definitely altered, its personal will no longer verify. The opposite of integrity is definitely often termed change – data becoming modified or damaged without authorization
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several. **Availability** – Making sure systems and information are accessible when needed. Even if info is kept secret and unmodified, it's of little employ in case the application is down or inaccessible. Availability means that authorized users can reliably access the particular application and its functions in a timely manner. Threats to availability incorporate DoS (Denial of Service) attacks, exactly where attackers flood a server with site visitors or exploit a vulnerability to accident the system, making this unavailable to legit users. Hardware failures, network outages, or even design issues that can't handle peak loads are furthermore availability risks. The particular opposite of supply is often identified as destruction or denial – data or even services are ruined or withheld
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. The particular Morris Worm's effects in 1988 had been a stark tip of the importance of availability: it didn't steal or transform data, but by making systems crash or even slow (denying service), it caused major damage
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These a few – confidentiality, integrity, and availability – are sometimes known as the "CIA triad" and are considered as the three pillars regarding security. Depending about the context, a great application might prioritize one over the particular others (for illustration, a public news website primarily cares that it's available as well as content honesty is maintained, confidentiality is less of an issue considering that the content is public; conversely, a messaging iphone app might put privacy at the top of its list). But a safeguarded application ideally ought to enforce all in order to an appropriate diploma. Many security controls can be comprehended as addressing one or more of those pillars: encryption works with confidentiality (by striving data so just authorized can read it), checksums plus audit logs support integrity, and redundancy or failover methods support availability.
## The DAD Triad (Opposites of CIA)
Sometimes it's beneficial to remember the flip side associated with the CIA triad, often called DAD:
- **Disclosure** – Unauthorized access in order to information (breach involving confidentiality).
- **Alteration** – Unauthorized modify of information (breach involving integrity).
- **Destruction/Denial** – Unauthorized destruction info or denial of service (breach of availability).
Protection efforts aim to be able to prevent DAD results and uphold CIA. A single strike can involve several of these elements. For example, a ransomware attack might equally disclose data (if the attacker burglarizes a copy) and even deny availability (by encrypting the victim's copy, locking them out). A website exploit might adjust data in a data source and thereby break the rules of integrity, and so forth.
## Authentication, Authorization, and Accountability (AAA)
Inside securing applications, especially multi-user systems, many of us rely on additional fundamental concepts also known as AAA:
1. **Authentication** – Verifying typically the identity of a great user or method. If you log inside with an username and password (or more firmly with multi-factor authentication), the system is definitely authenticating you – ensuring you usually are who you claim to be. Authentication answers the query: Which are you? Typical methods include accounts, biometric scans, cryptographic keys, or tokens. A core principle is that authentication should be strong enough in order to thwart impersonation. Poor authentication (like effortlessly guessable passwords or no authentication high should be) is really a frequent cause associated with breaches.
2. **Authorization** – Once identification is established, authorization settings what actions or perhaps data the authenticated entity is authorized to access. This answers: Exactly what are you allowed to carry out? For example, after you sign in, a good online banking app will authorize you to see your own account details but not someone else's. Authorization typically entails defining roles or permissions. The vulnerability, Broken Access Control, occurs when these kinds of checks fail – say, an opponent finds that simply by changing a list IDENTIFICATION in an WEB LINK they can see another user's files because the application isn't properly verifying their very own authorization. In truth, Broken Access Manage was recognized as typically the number one internet application risk found in the 2021 OWASP Top 10, seen in 94% of programs tested
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, illustrating how predominanent and important proper authorization is.
several. **Accountability** (and Auditing) – This refers to the ability to track actions in typically the system to the liable entity, which often means having proper working and audit tracks. If something moves wrong or dubious activity is diagnosed, we need in order to know who do what. Accountability is achieved through visiting of user behavior, and by having tamper-evident records. It works hand-in-hand with authentication (you can only hold someone dependable once you learn which bank account was performing a great action) and using integrity (logs by themselves must be shielded from alteration). Within application security, creating good logging and even monitoring is essential for both detecting incidents and executing forensic analysis following an incident. Since we'll discuss inside a later chapter, insufficient logging and even monitoring enables removes to go unknown – OWASP provides this as one other top issue, observing that without suitable logs, organizations may possibly fail to see an attack right up until it's far also late
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Sometimes you'll notice an expanded acronym like IAAA (Identification, Authentication, Authorization, Accountability) which just pauses out identification (the claim of identity, e. g. entering username, before real authentication via password) as an independent step. But the particular core ideas remain the same. A protected application typically enforces strong authentication, stringent authorization checks regarding every request, and maintains logs intended for accountability.
## Rule of Least Privilege
One of the most important design and style principles in protection is to give each user or even component the lowest privileges necessary in order to perform its operate, without more. This specific is called the theory of least opportunity. In practice, it implies if an application has multiple roles (say admin as opposed to regular user), typically the regular user company accounts should have simply no capacity to perform admin-only actions. If a new web application needs to access the database, the data source account it employs must have permissions only for the precise dining tables and operations essential – such as, in the event that the app by no means needs to remove data, the DB account shouldn't in fact have the ERASE privilege. By decreasing privileges, even when a great attacker compromises the user account or perhaps a component, the damage is contained.
A kampfstark example of not necessarily following least privilege was the Money One breach associated with 2019: a misconfigured cloud permission granted a compromised element (a web program firewall) to access all data through an S3 storage area bucket, whereas in the event that that component had been limited to only a few data, typically the breach impact would likely have been a long way smaller
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. Least privilege in addition applies with the signal level: if the module or microservice doesn't need certain accessibility, it shouldn't need it. Modern pot orchestration and foriegn IAM systems make it easier to implement granular privileges, yet it requires considerate design.
## Security in Depth
This specific principle suggests that security should become implemented in overlapping layers, to ensure that if one layer falls flat, others still give protection. Put simply, don't rely on any single security control; assume it could be bypassed, and have additional mitigations in place. Regarding an application, protection in depth may well 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 a great attacker bypasses your customer check). You safeguarded the database powering an internal fire wall, but you also write code that checks user permissions just before queries (assuming an attacker might break the rules of the network). When using encryption, you might encrypt delicate data inside the repository, but also implement access controls with the application layer and even monitor for unusual query patterns. Defense in depth is like the films of an onion – an opponent who gets by way of one layer need to immediately face one other. This approach counter tops the point that no one defense is certain.
For example, imagine an application is dependent on a website application firewall (WAF) to block SQL injection attempts. Defense comprehensive would claim the application form should still use safe coding practices (like parameterized queries) to sanitize inputs, in case the WAF longs fo a novel harm. A real scenario highlighting this was basically the situation of certain web shells or injection attacks of which were not recognized by security filtration – the interior application controls then served as the particular final backstop.
## Secure by Style and design and Secure by Default
These associated principles emphasize making security a basic consideration from the start of design and style, and choosing risk-free defaults. "Secure by design" means you want the system architecture with security found in mind – intended for instance, segregating sensitive components, using confirmed frameworks, and thinking of how each style decision could present risk. "Secure by default" means if the system is implemented, it will default to the most secure configurations, requiring deliberate action to make it less secure (rather compared to the other way around).
An illustration is default account policy: a firmly designed application may ship without having arrears admin password (forcing the installer to be able to set a strong one) – since opposed to using a well-known default pass word that users may forget to transform. Historically, many application packages were not protected by default; they'd install with open permissions or test databases or debug modes active, in case an admin opted to not lock them straight down, it left slots for attackers. After some time, vendors learned to invert this: now, databases and operating systems often come with secure configurations out and about of the pack (e. g., remote control access disabled, test users removed), in addition to it's up to the admin to be able to loosen if totally needed.
For designers, secure defaults suggest choosing safe catalogue functions by standard (e. g., arrears to parameterized inquiries, default to output encoding for internet templates, etc. ). It also means fail safe – if an aspect fails, it should fail inside a secure closed state quite than an unsafe open state. As an example, if an authentication service times out and about, a secure-by-default tackle would deny gain access to (fail closed) somewhat than allow this.
## Privacy simply by Design
This concept, carefully related to security by design, has gained prominence especially with laws like GDPR. It means that applications should be designed not just in be secure, but for respect users' privacy coming from the ground upward. In practice, this may well involve data minimization (collecting only just what is necessary), visibility (users know just what data is collected), and giving users control over their data. While privacy will be a distinct site, it overlaps heavily with security: an individual can't have privacy if you can't secure the personalized data you're responsible for. A lot of the most severe data breaches (like those at credit score bureaus, health insurance providers, etc. ) will be devastating not merely due to security malfunction but because they will violate the personal privacy of countless individuals. Thus, modern application security often works hand in hands with privacy considerations.
## Threat Modeling
The practice throughout secure design will be threat modeling – thinking like a good attacker to anticipate what could fail. During threat building, architects and programmers systematically go coming from the type of a good application to identify potential threats and even vulnerabilities. They ask questions like: What are we developing? What can get wrong? What will all of us do about this? A single well-known methodology with regard to threat modeling is usually STRIDE, developed from Microsoft, which stalls for six kinds of threats: Spoofing personality, Tampering with data, Repudiation (deniability involving actions), Information disclosure, Denial of assistance, and Elevation associated with privilege.
By jogging through each component of a system and considering STRIDE dangers, teams can discover dangers that may not be clear at first glance. For example, consider a simple online salaries application. Threat recreating might reveal of which: an attacker may spoof an employee's identity by guessing the session token (so we need to have strong randomness), could tamper with earnings values via a new vulnerable parameter (so we need suggestions validation and server-side checks), could conduct actions and afterwards deny them (so we need good audit logs to prevent repudiation), could take advantage of an information disclosure bug in a good error message in order to glean sensitive information (so we need to have user-friendly but hazy errors), might effort denial of assistance by submitting the huge file or even heavy query (so we need level limiting and resource quotas), or attempt to elevate freedom by accessing administrative functionality (so all of us need robust accessibility control checks). By means of this process, security requirements and countermeasures become much sharper.
Threat modeling is ideally done earlier in development (during the style phase) so that security is usually built in right away, aligning with the "secure by design" philosophy. It's the evolving practice – modern threat modeling may additionally consider misuse cases (how may the system always be misused beyond the intended threat model) and involve adversarial thinking exercises. We'll see its significance again when talking about specific vulnerabilities plus how developers may foresee and prevent them.
## Associated risk Management
Its not all safety measures issue is similarly critical, and assets are always in short supply. So another principle that permeates application security is risk management. This involves evaluating the possibilities of a risk along with the impact were it to arise. Risk is normally informally considered as a function of these 2: a vulnerability that's an easy task to exploit and even would cause extreme damage is high risk; one that's theoretical or might have minimal influence might be reduced risk. Organizations frequently perform risk tests to prioritize their security efforts. For example, an on the internet retailer might identify how the risk associated with credit card thievery (through SQL shot or XSS resulting in session hijacking) is very high, and as a result invest heavily in preventing those, although the risk of someone triggering minor defacement in a less-used webpage might be acknowledged or handled using lower priority.
Frameworks like NIST's or perhaps ISO 27001's risk management guidelines help throughout systematically evaluating and treating risks – whether by mitigating them, accepting these people, transferring them (insurance), or avoiding them by changing company practices.
One concrete response to risk managing in application safety measures is the design of a risk matrix or threat register where possible threats are shown along with their severity. This kind of helps drive choices like which insects to fix first or where in order to allocate more assessment effort. It's also reflected in plot management: if the new vulnerability is definitely announced, teams can assess the risk to their program – is that exposed to that vulnerability, how extreme is it – to determine how urgently to utilize the spot or workaround.
## Security vs. Simplicity vs. Cost
A discussion of guidelines wouldn't be complete without acknowledging typically the real-world balancing take action. Security measures could introduce friction or cost. Strong authentication might mean even more steps for the user (like 2FA codes); encryption might slow down performance a little bit; extensive logging may possibly raise storage fees. A principle to follow along with is to seek stability and proportionality – security should end up being commensurate with typically the value of what's being protected. Overly burdensome security that will frustrates users may be counterproductive (users might find unsafe workarounds, with regard to instance). The skill of application safety is finding remedies that mitigate hazards while preserving a new good user encounter and reasonable cost. Fortunately, with contemporary techniques, many safety measures can end up being made quite seamless – for example of this, single sign-on alternatives can improve equally security (fewer passwords) and usability, and efficient cryptographic libraries make encryption scarcely noticeable regarding functionality.
In summary, these kinds of fundamental principles – CIA, AAA, very least privilege, defense comprehensive, secure by design/default, privacy considerations, danger modeling, and risk management – form the mental framework intended for any security-conscious specialist. They will appear repeatedly throughout information as we look at specific technologies and even scenarios. Whenever a person are unsure about a security decision, coming back to these basics (e. g., "Am We protecting confidentiality? Are generally we validating integrity? Are we minimizing privileges? Do we possess multiple layers involving defense? ") could guide you to some more secure outcome.
With one of these principles in mind, we can right now explore the specific hazards and vulnerabilities that will plague applications, and even how to protect against them.