Prototype Pollution
Description
An application object, method or module can be overwritten with malicious logic due to the lack of validations and the nature of the JavaScript language.
Impact
- Overwrite or pollute the behavior of existing methods in the application.
- Lead to dangerous vulnerabilities such as XSS, SQLi, RCE, among others.
Recommendation
- Implement integrity validations on the vulnerable objects.
- Restrict and Discourage the use harmful properties such as _proto_ in the system objects.
Threat
Authenticated attacker from the Internet.
Expected Remediation Time
⌚ 60 minutes.
Score
Default score using CVSS 3.1. It may change depending on the context of the src.
Base
- Attack vector: N
- Attack complexity: H
- Privileges required: L
- User interaction: N
- Scope: U
- Confidentiality: N
- Integrity: L
- Availability: N
Temporal
- Exploit code maturity: P
- Remediation level: U
- Report confidence: R
Result
- Vector string: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N/E:P/RL:U/RC:R
- Score:
- Base: 3.1
- Temporal: 2.8
- Severity:
- Base: Low
- Temporal: Low
Score 4.0
Default score using CVSS 4.0. It may change depending on the context of the src.
Base 4.0
- Attack vector: N
- Attack complexity: H
- Attack Requirements: N
- Privileges required: L
- User interaction: N
- Confidentiality (VC): N
- Integrity (VI): L
- Availability (VA): N
- Confidentiality (SC): N
- Integrity (SI): N
- Availability (SA): N
Threat 4.0
- Exploit maturity: P
Result 4.0
- Vector string: CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P
- Score:
- CVSS-BT: 1.3
- Severity:
- CVSS-BT: Low
Compliant code
There are no harmful functionalities on vulnerable objects
function modifyPrototype(moduleName, deleteMethod, newMethod) {
var newMod = new moduleName;
//Add new method to the object, without altering the original
newMod.${newMethod} = function() {
//Add functionality to object
};
return newMod;
}
Non compliant code
There are functionalities that can be overwritten due to insecure coding practices
function modifyPrototype(moduleName, deleteMethod, newMethod) {
// modifying the prototype of a module from within another function
var newMod = require(moduleName);
delete newMod[deleteMethod];
newMod.${newMethod} = function() {
// function body that modifies the original method
};
module.exports = newMod;
}
Requirements
Fixes
