Check for Log4j Vulnerability With External Attack Surface Scanning

Date: 
15 December 2021    |    
Author:
Ralph Moonen - Technical Director


With the discovery of the Log4j vulnerability past weekend, great uncertainties are at play at organizations world wide. Various customers have reached out to us to ask for assistance in this matter. In case you are still looking for help; our team can perform External Attack Surface Scanning: a quick scan of your external, internet-facing systems for the Log4Shell vulnerability with our own automated tool.

What is External Attack Surface Scanning?

External Attack Surface Scanning uses an automated tool that can find and crawl webapps, and then test the most common injection vectors for the Log4Shell vulnerability such as HTTP Headers, GET/POST requests and Cookies.
It is a broad scan, prioritizing wideness over depth. This means that not all injection vectors might be found, however, it covers all commonly scanned-for points and therefore gives a reasonable picture of the attack surface for Log4Shell. Please note that currently other potential vulnerable protocols such as SMTP are not yet included in our scanner. However we are working hard to include those also, and we will let our customers know when we have finalized it (and can re-scan existing customer’s infra for better coverage).

Also important to know is that for optimal results of this scan, customers need to put our IP addresses on the allowlist of any WAF or IPS/IDS:

64.225.82.44
178.128.141.106
134.209.139.165

The scan is non-intrusive and uses the DNS requests that results from triggering the vulnerability to detect if an injection point is vulnerable. At no point is a Java class file actually downloaded and/or executed.

Verified Manually

All results are manually verified so there will be very little chance of false positives. The report will consist of the list of tested sites/IPs and the subset thereof that is vulnerable to CVE-2021-44228 and related CVEs that can be tested externally.


Deeper Testing

Deeper testing is also possible, manually going through many more injection vectors and testing potential contextual vulnerabilities (i.e. after logging into an application). This is a part of our standard VAPT service, be it black box, gray box, or crystal box pentesting.

For more information about Log4Shell, how it works, and what the next steps are, please refer to our Log4Shell blog.

Fact sheets

External Attack Surface Scanning

Check for Log4j Vulnerability with our Automated Tool

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