The guidance suggested below is accurate as of 16 December 2021.
On 9 December, Apache publicly disclosed the discovery of a critical vulnerability in their open-source Apache Log4j2 utility. The bug is embedded in software called Log4j, a widely used, publicly available logging utility. The free software is leveraged by cybersecurity practitioners to record (log) user activity and application behavior for subsequent examination to identify potential anomalies.
Following Apache’s disclosure, NIST reported the vulnerability (CVE-2021-44228) on 10 December. Affected versions of Log4j range from Log4j2 2.0-beta9 through Log4j2 2.14.1. Major service providers including Amazon Web Services, Microsoft, Cisco, Google Cloud and IBM have all reported that some of their services are vulnerable to the bug and the companies are working fastidiously to mitigate the issues.
To help determine whether or not your network is vulnerable or has been exploited, you can leverage this list of hashes associated with vulnerable software versions and you can also use this threat hunting guide to see if the exploit is on your network. In order to effectively mitigate this vulnerability, it is critical for organizations to upgrade to the latest version of the utility – Log4j2 2.16.0. If there is a reason your organization cannot upgrade to 2.16.0, please explore this repair guidance (for versions 2.10 and above).
If you are a DIB contractor and find your network has been exploited, please load the new version immediately. Defense Industrial Base companies should follow up by reporting the network exploitation attempts to the National Defense Information Sharing and Analysis Center (NDISAC) and/or the Department of Defense DIB Collaborative Information Sharing Environment.