Bump minimist from 1.2.5 to 1.2.6 in /web-widgets

[dependabot]

Bumps minimist from 1.2.5 to 1.2.6.

Commits

• 7efb22a 1.2.6
• ef88b93 security notice for additional prototype pollution issue
• c2b9819 isConstructorOrProto adapted from PR
• bc8ecee test from prototype pollution PR
• See full diff in compare view

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[secureflag-knowledge-base]

Prototype Pollution

Click here to find a Prototype Pollution training lab

Description

The problem lies with the manner in which JavaScript implements inheritance by using a prototype. What this means, in a nutshell, is that every object contains a reference to the prototype of its class. When a property is requested from a particular object, the runtime first checks if the instance has the aforementioned property; otherwise, it looks it up in the prototype chain, recursively.

The reference to the prototype is available via the __proto__ property. The fact that the prototype itself is just an object that has properties makes the whole structure susceptible to unwanted alteration when properties have been assigned from any untrusted input.

Read more

Impact

The impact of Prototype Pollution is ultimately determined by the sensitivity and criticality of the data ingested by the application. It is not a vulnerability that is dangerous per se; rather, it all depends on how the application uses such untrusted properties. In other words, it merely alters the program data and flow.

Scenario 1

The following example considers an object (in a JavaScript console):

> o = {x: 123, __proto__: {toString: () => console.log('Triggered!')}}
{ x: 123 }
> o + ''
Triggered!
'undefined'

We have created an object with its own prototype that redefines the toString property.

While this is important, it is unlikely that some kind of injection (e.g., an injection via GET parameters, cookies, etc.) ends up creating a JavaScript function (() => console.log('Triggered!') in the above example unless the application uses eval or some other mechanism. Instead, it is likely that an attacker is able to place strings, numbers, an array, or objects.

In this case, there is no direct code execution, and the impact is merely that of adding another property to the object; since we are already injecting __proto__ itself, this is not particularly interesting. It could still be possible to introduce a denial of service by overwriting some methods with non-function values, for example {toString: 123}.

Scenario 2

In this case, however, the application allows the alteration of an existing prototype. Consider the following:

const someObject = {};
const someOtherObject = {};

// ...

someObject[UNTRUSTED_NAME] = UNTRUSTED_VALUE;

// ...

if (someOtherObject.isAdminEnabled) {
    // do some sensitive stuff
}

Being able to control UNTRUSTED_NAME and UNTRUSTED_VALUE can be used to alter the prototype of all the other objects (not only someObject) with the ultimate effect of setting someOtherObject.isAdminEnabled to true. Specifically, using these values:

UNTRUSTED_NAME = '__proto__';
UNTRUSTED_VALUE = {isAdminEnabled: 'whatever'};

Prevention

There are different approaches to preventing Prototype Pollution, the most trivial of which is to disallow untrusted data being assigned to arbitrary properties altogether. If this is not possible, developers might implement some filtering so that it is not possible to overwrite __proto__ or other special properties of an object.

Testing

Verify that the application protects against JavaScript injection attacks, including for eval attacks, remote JavaScript includes, DOM XSS, and JavaScript expression evaluation.

• OWASP ASVS: 5.3.6
• OWASP Testing Guide: Testing for JavaScript Execution

References

The Daily Swig - Prototype pollution: The dangerous and underrated vulnerability impacting JavaScript applications

Medium - What is Prototype Pollution and why is it such a big deal?

View this in the SecureFlag Knowledge Base

[secure-code-warrior-for-github]

Micro-Learning Topic: Injection attack (Detected by phrase)

Matched on "injection attack"

Injection flaws, such as SQL, NoSQL, OS, and LDAP injection, occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization. Source: https://www.owasp.org/index.php/Category:OWASP_Top_Ten_Project

Try this challenge in Secure Code Warrior

Micro-Learning Topic: DOM-based cross-site scripting (Detected by phrase)

Matched on "DOM XSS"

What is this? (2min video)

DOM-based cross-site scripting vulnerabilities occur when unescaped input is processed by client-side script and insecurely written into the page Document Object Model (DOM). This will result in immediate changes to the page, potentially without any call to the server. When HTML or script is included in the input, it will be processed by a user's browser as HTML or script and can alter the appearance of the page or execute malicious scripts in their user context.

Try this challenge in Secure Code Warrior

Micro-Learning Topic: Cross-site scripting (Detected by phrase)

Matched on "XSS"

What is this? (2min video)

Reflected cross-site scripting vulnerabilities occur when unescaped input is displayed in the resulting page displayed to the user. When HTML or script is included in the input, it will be processed by a user's browser as HTML or script and can alter the appearance of the page or execute malicious scripts in their user context.

Try this challenge in Secure Code Warrior

Micro-Learning Topic: Denial of service (Detected by phrase)

Matched on "denial of service"

The Denial of Service (DoS) attack is focused on making a resource (site, application, server) unavailable for the purpose it was designed. There are many ways to make a service unavailable for legitimate users by manipulating network packets, programming, logical, or resources handling vulnerabilities, among others. Source: https://www.owasp.org/index.php/Denial_of_Service

Try this challenge in Secure Code Warrior