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Insecure Processing of Data

This category covers the following issues:

Cross-Site Scripting​

About XSS

What is Cross-Site Scripting?​

Cross-site scripting (XSS) is a type of security vulnerability that allows attackers to inject malicious code into web pages viewed by other users. This occurs when an application fails to properly sanitize user input and injects untrusted data into a web page without validating or encoding it.

XSS attacks can occur in different forms, such as reflected, stored, or DOM-based, and can affect various types of web applications, including social media, e-commerce, and online banking sites.

Attackers can use various techniques, such as phishing emails, web forms, or malicious links, to trick users into visiting or interacting with web pages that contain malicious code.

Check out this video for a high-level explanation:

What is the impact of Cross-Site Scripting?​

Cross-site scripting (XSS) can lead to various security threats and risks, such as:

  • Information theft: XSS attacks can steal sensitive information, such as login credentials, credit card details, or other personally identifiable information, by injecting malicious code that collects and transmits user data to attackers.
  • Account hijacking: XSS attacks can hijack user sessions by injecting malicious code that takes over user sessions, allowing attackers to perform unauthorized actions on the website or gain access to user accounts.
  • Data tampering: XSS attacks can modify or delete data on a website by injecting malicious code that alters the content of web pages, leading to data tampering, data corruption, or other types of malicious activities.
  • Malware distribution: XSS attacks can distribute malware by injecting malicious code that downloads and installs malicious software on the user's computer, leading to malware infections or other types of cyber attacks.

Overall, XSS attacks can compromise the confidentiality, integrity, and availability of data, leading to a range of security threats and risks.

How to prevent Cross-Site Scripting?​

To prevent XSS vulnerabilities, you can take the following steps:

  • Input validation and sanitization: Ensure that all user input is validated and sanitized before being used to generate web pages or manipulate other data. Input validation should include validating the data type, length, and format, and filtering out any special characters that could be used to inject malicious code.
  • Output encoding: Encode all output to protect against XSS attacks. Use output encoding techniques such as HTML entity encoding, URL encoding, and JavaScript encoding to encode user input and output to the browser.
  • Use security headers: Implement security headers to protect against XSS attacks, such as Content-Security-Policy (CSP) and X-XSS-Protection. CSP can help prevent XSS attacks by allowing only trusted sources of content to be loaded on a page, while X-XSS-Protection can help prevent the browser from rendering pages that contain malicious scripts.
  • Session management: Implement secure session management mechanisms, such as session cookies, to protect against session hijacking and other attacks.
  • Secure coding practices: Use secure coding practices to prevent XSS vulnerabilities. This includes using libraries and frameworks that are designed to prevent XSS attacks, testing code for vulnerabilities, and using secure coding practices such as input validation and output encoding.
  • Regular security audits: Regularly audit your system for security vulnerabilities, including XSS vulnerabilities. Use automated tools and manual testing to identify potential issues and fix them before they can be exploited.

References​

Taxonomies​

Explanation & Prevention​

Training​

Fixing Cross-Site Scripting​

A Cross-Site Scripting vulnerability has been detected by our runtime engines.

Fixing advice for common languages is listed below:

CRLF Injection​

About CRLF Injection

What is a CRLF injection?​

A CRLF (Carriage Return Line Feed) Injection vulnerability is a type of security issue that occurs when an attacker can inject a CRLF sequence into an HTTP stream. This is significant because CRLF sequences are used to separate headers and other elements in HTTP protocol.

The name "CRLF" comes from the special characters used to denote the end of a line in many text formats, specifically Carriage Return (CR, or \r) and Line Feed (LF, or \n).

If an application does not properly sanitize user input and allows raw user input to be inserted into HTTP headers or other parts of an HTTP response, an attacker could inject CRLF sequences along with arbitrary HTTP headers or other content.

This could lead to several types of attacks, including:

  1. HTTP Response Splitting: This is where the attacker causes the server to send a corrupted HTTP response, which can trick the browser into executing a malicious script or visiting a malicious site. This can lead to cross-site scripting (XSS) or cache poisoning attacks.
  2. HTTP Header Injection: The attacker injects malicious headers into the HTTP response, which can be used to perform redirection attacks, or to set malicious cookies.
  3. Log Injection: If the injected data is written to a log file, the attacker can manipulate the contents of the log file, which can lead to further attacks or misinformation.

Check out this video for a high-level explanation:

What is the impact of CRLF injection?​

CRLF Injection vulnerabilities can have several potential impacts, depending on how they are exploited. Here are a few examples:

  1. HTTP Response Splitting: This can lead to a variety of attacks, including cross-site scripting (XSS), session fixation, or cache poisoning. By manipulating the HTTP response, an attacker can trick a user's browser into executing malicious scripts or visiting malicious sites.
  2. HTTP Header Injection: By injecting malicious headers into the HTTP response, an attacker can perform redirection attacks, tricking the user's browser into visiting a malicious site. They can also set malicious cookies, potentially leading to session hijacking or other attacks that exploit cookies.
  3. Log Injection: If the injected data is written to a log file, an attacker can manipulate the contents of the log file. This can lead to misinformation, obscuring the attacker's activities and making it harder to detect or investigate attacks. In some cases, if the log files are later displayed or processed unsafely, log injection can even lead to further attacks such as XSS or Code Execution.

How to prevent CRLF injection?​

Preventing CRLF Injection vulnerabilities primarily involves validating and sanitizing user input. Here are some specific steps you can take:

  1. Input Validation: Validate all user input to ensure it conforms to the expected format. For example, if you're expecting a numerical ID, make sure the input is indeed a number.
  2. Reject or Sanitize CRLF Sequences: If your application has no legitimate reason to include CRLF sequences in user input, you should reject any input that contains them. If there are valid reasons for including CRLF sequences, you should sanitize the input to ensure that they can't be used to inject arbitrary headers or split HTTP responses.
  3. Use Safe APIs: Some programming languages and frameworks provide APIs that automatically sanitize header values, making it impossible to inject CRLF sequences. Whenever possible, use these APIs instead of manually constructing HTTP headers.
  4. URL Encoding: If user input is included in URLs, make sure it's URL-encoded. This can prevent many types of injection attacks, including CRLF injection.
  5. Content Security Policy (CSP): Implementing a strong CSP can help to mitigate the impact of potential CRLF vulnerabilities, as it can prevent the execution of injected scripts.

References​

Taxonomies​

Explanation & Prevention​

Training​

Fixing CRLF Injection Issues​

A CRLF injection vulnerability has been detected by our runtime engines. Fix CRLF injections by ensuring that:

  • Any input is validated against the expected schema, this includes rejecting or sanitizing CRLF sequences.
  • Safe APIs are used whenever possible instead of manually constructing HTTP headers.
  • User input that is included in URLs is URL encoded.
  • A robust Content Security Policy (CSP) is defined to mitigate the impact of CRLF injections.

XML Processing Issues​

About XML External Entities

What is XML External Entities (XXE) injection?​

XML External Entities (XXE) injection is a type of security vulnerability that allows attackers to exploit the processing of XML data by an application.

This occurs when an application accepts XML data from an untrusted source and processes it without proper validation, allowing the inclusion of external entities that can be malicious or contain sensitive information.

As a result, attackers can perform various malicious activities, such as stealing user data, executing arbitrary code, or performing denial-of-service attacks.

Check out this video for a high-level explanation:

What is the impact of XXE injection?​

XML External Entities (XXE) injection can lead to various security threats and risks, such as:

  • Information theft: XXE attacks can steal sensitive information, such as login credentials, credit card details, or other personally identifiable information, by injecting malicious code or entities that collect and transmit user data to attackers.
  • Server-side request forgery: XXE attacks can initiate requests to systems that are accessible from the affected web server.
  • Denial of service: XXE attacks can cause denial-of-service (DoS) attacks by injecting malicious code or entities that consume system resources, such as CPU or memory, leading to system crashes or slowdowns.
  • Arbitrary code execution: XXE attacks can execute arbitrary code on the server by injecting malicious code or entities that exploit vulnerabilities in the application or the underlying operating system.

How to prevent XXE injection?​

To prevent XML External Entities (XXE) injection, it is important to follow security best practices and implement appropriate security measures, such as:

  • Disable external entity processing: Disable the processing of external entities in XML parsers and libraries to prevent XXE vulnerabilities.
  • Use secure parsers and libraries: Use secure parsers and libraries that support secure XML processing.
  • Use input validation: Validate user input to ensure that it is safe and does not contain malicious code or entities.
  • Keep software up to date: Keep software and security protocols up to date, as new vulnerabilities and security patches are regularly released.

References​

Taxonomies​

Explanation & Prevention​

Training​

Soap XML Injection​

An XML injection has been detected by our runtime engines.

Fixing advice for common languages is listed below:

Buffer Overflows​

About Buffer Overflows

What is a buffer overflow?​

A buffer overflow is a type of software vulnerability that occurs when a program or application attempts to write data to a buffer that is too small to hold the data. As a result, the excess data overwrites adjacent memory locations, which can cause the program to crash, execute arbitrary code, or behave in unintended ways.

Buffer overflows can occur in many types of programs, including web applications, operating systems, and device drivers. They can be caused by a range of factors, including improper input validation, improper handling of dynamic memory allocation, and the use of unsafe functions.

Check out this video for a high-level explanation:

What is the impact of a buffer overflow?​

The impact of a buffer overflow vulnerability can have serious consequences, including:

  • Crashes and system instability: Buffer overflows can cause the program or system to crash, which can result in data loss, downtime, and system instability.
  • Code execution: In some cases, a buffer overflow can allow an attacker to execute arbitrary code on the system, which can result in unauthorized access, data theft, or system compromise.
  • Denial of service: An attacker can use a buffer overflow to cause the program or system to consume excessive resources, resulting in a denial of service (DoS) attack.

How to prevent a buffer overflow?​

To prevent buffer overflow vulnerabilities, developers can implement mitigation strategies, including:

  • Input validation: Implement strict input validation to ensure that data entered by users is within expected limits and does not exceed buffer sizes.
  • Use memory-safe languages: Use memory-safe languages such as Java, C#, or Rust, which have built-in memory management and can help prevent buffer overflow vulnerabilities.
  • Implement stack canaries: Use stack canaries to detect and prevent buffer overflow attacks.
  • Use safe coding practices: Use secure coding practices such as bounds checking, memory allocation, and exception handling to prevent buffer overflow vulnerabilities.
  • Code review and testing: Conduct regular code reviews and testing to identify potential buffer overflow vulnerabilities and fix them before they can be exploited.

References​

Taxonomies​

Explanation & Prevention​

Training​

Fixing Buffer Overflows​

A potential buffer overflow has been detected by our runtime engines.

Fixing advice for common languages is listed below:

Format Strings​

About Format Strings

What is a format string vulnerability?​

A format string vulnerability is a type of software vulnerability that can occur in applications that use format strings to process user input. Format string vulnerabilities can be exploited by attackers to read or write arbitrary memory locations, execute arbitrary code, or cause the program to crash.

The vulnerability occurs when a format string that is controlled by an attacker is passed to a function that processes it without proper validation or sanitization. This can allow the attacker to manipulate the format string to access or modify memory locations that are not intended to be accessed or modified.

What is the impact of format string vulnerabilities?​

Format string vulnerabilities can have serious consequences, including:

  • Information disclosure: An attacker can use a format string vulnerability to read sensitive information from memory, such as passwords, encryption keys, or other data.
  • Remote code execution: An attacker can use a format string vulnerability to execute arbitrary code on the system, allowing them to take control of the system or steal sensitive data.
  • Denial of service: An attacker can use a format string vulnerability to cause the program to crash or enter an infinite loop, resulting in a denial of service (DoS) attack.

How to prevent format string vulnerabilities?​

To prevent format string vulnerabilities, developers can implement several strategies, including:

  • Input validation: Validate input to ensure that it is within expected limits and does not exceed buffer sizes or contain unexpected characters.
  • Use of safe formatting functions: Use safe formatting functions that provide bounds checking, such as snprintf or printf_s, rather than unsafe functions like printf.
  • String sanitization: Sanitize format strings to remove any characters that could be used to exploit a vulnerability, such as %n, which can be used to write arbitrary data to a memory location.
  • Use of static analysis tools: Use static analysis tools to identify potential format string vulnerabilities during code review and testing.

References​

Taxonomies​

Explanation & Prevention​

Training​

Fixing Format String Issues​

A format string vulnerability has been detected by our runtime engines.

Fixing advice for common languages is listed below:

Last updated on by Stefan Streichsbier