Das Open Web Application Security Project pflegt eine regelmäßig aktualisierte Liste der wichtigsten Sicherheitsbedenken bei Webanwendungen.
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Das Open Web Application Security Project oder OWASP ist eine internationale Non-Profit-Organisation, die sich der Sicherheit von Webanwendungen widmet. Eines der Grundprinzipien von OWASP ist, dass alle Materialien frei verfügbar und auf ihrer Website leicht zugänglich sind, so dass jeder die Sicherheit seiner eigenen Webanwendungen verbessern kann. Sie bieten Materialien wie Dokumentationen, Tools, Videos und Foren an. Ihr wohl bekanntestes Projekt sind die OWASP Top 10.
The OWASP Top 10 is a regularly updated report outlining security concerns for web application security, focusing on the 10 most critical risks. The report is put together by a team of security experts from all over the world. OWASP refers to the Top 10 as an ‘awareness document’ and they recommend that all companies incorporate the report into their processes in order to minimize and/or mitigate security risks.
Below are the security risks reported in the OWASP Top 10 2021 report:
Access control refers a system that controls access to information or functionality. Broken access controls allow attackers to bypass authorization and perform tasks as though they were privileged users such as administrators. For example a web application could allow a user to change which account they are logged in as simply by changing part of a URL, without any other verification.
Zugriffskontrollen können geschützt werden, indem sichergestellt wird, dass eine Webanwendung Autorisierungstoken* verwendet und strenge Kontrollen für sie festlegt.
*Many services issue authorization tokens when users log in. Every privileged request that a user makes will require that the authorization token be present. This is a secure way to ensure that the user is who they say they are, without having to constantly enter their login credentials.
If web applications do not protect sensitive data such as financial information and passwords using encryption, attackers can gain access to that data and sell or utilize it for nefarious purposes. They can also steal sensitive information by using an on-path attack.
The risk of data exposure can be minimized by encrypting all sensitive data, authenticating all transmissions, and disabling the caching* of any sensitive information. Additionally, web application developers should take care to ensure that they are not unnecessarily storing any sensitive data.
*Caching is the practice of temporarily storing data for re-use. For example, web browsers will often cache webpages so that if a user revisits those pages within a fixed time span, the browser does not have to fetch the pages from the web.
Injection-Angriffe erfolgen, wenn nicht vertrauenswürdige Daten über eine Formulareingabe oder eine andere Datenübermittlung an eine Webanwendung an einen Code-Interpreter gesendet werden. Angreifer könnten beispielsweise SQL-Datenbankcode in ein Formular eingeben, das einen Benutzernamen in Klartext erwartet. Wenn diese Formulareingabe nicht entsprechend gesichert ist, wird der SQL-Code ausgeführt. Das ist als SQL-Injection-Angriff bekannt.
The Injection category also includes cross-site scripting (XSS) attacks, previously their own category in the 2017 report. Mitigation strategies for cross-site scripting include escaping untrusted HTTP requests, as well as using modern web development frameworks like ReactJS and Ruby on Rails, which provide some built-in cross-site scripting protection.
In general, Injection attacks can be prevented by validating and/or sanitizing user-submitted data. (Validation means rejecting suspicious-looking data, while sanitization refers to cleaning up the suspicious-looking parts of the data.) In addition, a database admin can set controls to minimize the amount of information an injection attack can expose.
Erfahren Sie mehr darüber , wie Sie SQL-Injection verhindern können.
Insecure Design includes a range of weaknesses that can be emdedded in the architecture of an application. It focuses on the design of an application, not its implementation. OWASP lists the use of security questions (e.g. "What street did you grow up on?") for password recovery as one example of a workflow that is insecure by design. No matter how perfectly such a workflow is implemented by its developers, the application will still be vulnerable, because more than one person can know the answer to those security questions.
The use of threat modeling prior to an application's deployment can help mitigate these types of vulnerabilities.
Sicherheitsrelevante Fehlkonfigurationen sind die häufigste Schwachstelle in der Liste und oft das Ergebnis der Nutzung von Standardkonfigurationen oder übermäßig ausführlicher Fehleranzeigen. Beispielsweise kann eine Anwendung Benutzern Fehler übermäßig detailliert beschreiben, die Schwachstellen in der Anwendung aufdecken können. Das kann abgemildert werden, indem nicht genutzte Features aus dem Code entfernt werden und für allgemeinere Fehlermeldungen gesorgt wird.
The Security Misconfiguration category includes the XML External Entities (XEE) attack — previously its own category in the 2017 report. This is an attack against a web application that parses XML* input. This input can reference an external entity, attempting to exploit a vulnerability in the parser. An ‘external entity’ in this context refers to a storage unit, such as a hard drive. An XML parser can be duped into sending data to an unauthorized external entity, which can pass sensitive data directly to an attacker. The best ways to prevent XEE attacks are to have web applications accept a less complex type of data, such as JSON, or at the very least to patch XML parsers and disable the use of external entities in an XML application.
*XML or Extensible Markup Language is a markup language intended to be both human-readable and machine-readable. Due to its complexity and security vulnerabilities, it is now being phased out of use in many web applications.
Many modern web developers use components such as libraries and frameworks in their web applications. These components are pieces of software that help developers avoid redundant work and provide needed functionality; common example include front-end frameworks like React and smaller libraries that used to add share icons or A/B testing. Some attackers look for vulnerabilities in these components which they can then use to orchestrate attacks. Some of the more popular components are used on hundreds of thousands of websites; an attacker finding a security hole in one of these components could leave hundreds of thousands of sites vulnerable to exploit.
Component developers often offer security patches and updates to plug up known vulnerabilities, but web application developers do not always have the patched or most-recent versions of components running on their applications. To minimize the risk of running components with known vulnerabilities, developers should remove unused components from their projects, as well as ensure that they are receiving components from a trusted source that are up to date.
Sicherheitslücken in Authentifizierungssystemen (Anmeldung) können Angreifern Zugriff auf Benutzerkonten und sogar die Möglichkeit geben, mithilfe eines Administratorkontos ein ganzes System zu kompromittieren. Zum Beispiel kann ein Angreifer eine Liste mit Tausenden bekannten Kombinationen aus Benutzernamen und Passwörtern nehmen, die er im Zuge einer Datenschutzverletzung erhalten hat, und ein Skript verwenden, das alle diese Kombinationen in einem Anmeldesystem ausprobiert, um zu sehen, welche davon funktionieren.
Einige Strategien zur Minimierung von Sicherheitslücken bei der Authentifizierung verlangen eine Zwei-Faktor-Authentifizierung (2FA) und begrenzen oder verzögern wiederholte Anmeldeversuche mit Durchsatzbegrenzung.
Many applications today rely on third-party plugins and other external sources for their functionality, and they do not always make sure that updates and data from those sources have not been tampered with and originate from an expected location. For instance, an application that automatically accepts updates from an outside source could be vulnerable to an attacker uploading their own malicious updates, which would then be distributed to all installations of that application. This category also includes insecure deserialization exploits: these attacks are the result of deserializing data from untrusted sources, and they can result in serious consequences like DDoS attacks and remote code execution attacks.
To help ensure data and updates have not had their integrity violated, application developers should use digital signatures to verify updates, check their software supply chains, and ensure that continuous integration/continuous deployment (CI/CD) pipelines have strong access control and are configured correctly.
Viele Webanwendungen ergreifen nicht genügend Maßnahmen, um Datenschutzverletzungen zu erkennen. Die durchschnittliche Zeit, bis ein Verstoß erkannt wird, beträgt ca. 200 Tage nach seinem Auftreten. Das gibt Angreifern viel Zeit, um Schaden anzurichten, bevor eine Reaktion erfolgt. OWASP empfiehlt Webentwicklern, die Protokollierung und Überwachung sowie Pläne für die Reaktion auf Vorfälle zu implementieren, um sicherzustellen, dass sie auf Angriffe auf ihre Anwendungen aufmerksam gemacht werden.
Server-Side Request Forgery (SSRF) is an attack in which someone sends a URL request to a server that causes the server to fetch an unexpected resource, even if that resource is otherwise protected. An attacker might, for example, send a request for www.example.com/super-secret-data/
, even though web users are not supposed to be able to navigate to that location, and get access to super secret data from the server's response.
There are a number of possible mitigations for SSRF attacks, and one of the most important is to validate all URLs coming from clients. Invalid URLs should not result in a direct, raw response from the server.
For a more technical and in-depth look at the OWASP Top 10, see the official report.