Node.js ReDoS Vulnerability

Researchers have disclosed vulnerabilities in the Node.js JavaScript-based runtime. They claim that an attacker could exploit these vulnerabilities to perform regular expression (regex) denial-of-service (ReDos) attacks on web applications and servers using Node.js.

Threat ID:: CC-2621
Category:: Exploit
Threat Severity:: Medium
Threat Vector:
Published:: 21 August 2018 12:00 AM

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Summary

Threat details

They claim that an attacker could exploit these vulnerabilities to perform regular expression (regex) denial-of-service (ReDos) attacks on web applications and servers using Node.js.

The vulnerabilities lie in how Node.js-based applications accept regexes. If the application library is not designed to handle various edge cases then the inputted regex can cause the application to freeze whilst the server attempts to analyse it. As most JavaScript servers use a single-thread execution model, where every request is handled by the same thread, this can cause the entire server to hang or crash.

A ReDoS attack exploits the fact that most regex implementations can be forced into extreme computational situations that cause them to work very slowly. Malicious regexes can be queued so even if a device outputs one regex it will immediately be forced into computing another.

For further information

Remediation steps

Type	Step
	Fixes for the affected modules can be found here. Users and administrators are advised to apply these updates immediately.

Last edited: 17 February 2020 12:50 pm