CVE-2021-23354 : Exploit Details and Defense Strategies

A vulnerability has been identified in the printf package before version 0.6.1, leading to Regular Expression Denial of Service (ReDoS) due to a vulnerable regular expression with cubic worst-case time complexity.

Understanding CVE-2021-23354

This CVE pertains to a vulnerability in the printf package that can be exploited for Regular Expression Denial of Service (ReDoS) by utilizing a specific regex string found in lib/printf.js.

What is CVE-2021-23354?

The package printf before version 0.6.1 is prone to Regular Expression Denial of Service (ReDoS) due to a vulnerable regular expression, potentially leading to service disruption.

The Impact of CVE-2021-23354

The vulnerability allows attackers to exploit the package's regex string, consuming excessive resources and causing system slowdowns or crashes, affecting the availability of services.

Technical Details of CVE-2021-23354

This section covers the technical aspects of the CVE, including the vulnerability description, affected systems, and exploitation mechanism.

Vulnerability Description

The vulnerable regular expression in lib/printf.js has cubic worst-case time complexity, enabling attackers to launch ReDoS attacks, impacting system availability.

Affected Systems and Versions

The printf package versions prior to 0.6.1 are affected by this vulnerability, exposing systems to ReDoS attacks via the flawed regex string.

Exploitation Mechanism

Attackers can exploit the vulnerable regex string /%(?:(([\w_.]+))|([1-9]\d*)$)?([0 +-]*)(*|\d+)?(.)?(*|\d+)?[hlL]?([%bscdeEfFgGioOuxX])/g to launch ReDoS attacks on systems running the affected printf versions.

Mitigation and Prevention

Protecting systems from CVE-2021-23354 requires immediate action and long-term security measures to prevent exploitation.

Immediate Steps to Take

Immediately update the printf package to version 0.6.1 or higher to mitigate the ReDoS vulnerability and enhance system security.

Long-Term Security Practices

Implement regex best practices, monitor for regex anomalies, and educate developers on secure regex usage to prevent similar vulnerabilities in the future.

Patching and Updates

Regularly apply security patches and updates to all software components, including the printf package, to address known vulnerabilities and enhance overall system security.