Trending Internet Scanning on Apache Log4j Vulnerability

Exploit activity for Apache Log4j vulnerability - CVE-2021-44228

UPDATE 16-Dec-21, 4:00PM ET: Tentative results for #Log4Shell activity by hour showing "Researcher" and "Non-Researcher" breakdown as observed by GreyNoise. May not be 100% accurate but it should give an idea of what we are observing. "Researcher" is defined by IPs that GreyNoise knows to be attributable scanners for commercial or research purposes, usually listed as "benign" in our data. "Non-Researcher" is defined as everything else. The researcher numbers seem to flatline, but we believe this due to the scale of the plot and new infrastructure spun up by various researchers that have not yet been accounted for. We will try to update this later for a better retroactive understanding.

UPDATE 16-Dec-21, 1:00PM ET: GreyNoise Research has compiled a set of sample Log4Shell (CVE-2021-44228) payloads observed in the wild. These samples are intended to provide individuals with a clearer idea of some of the variation we're seeing, including esoteric protocols such as iiop.

UPDATE 15-Dec-21, 11:00PM ET: As of 15-Dec-21, GreyNoise Research is seeing a decrease in the number of unique IP addresses scanning for the Apache Log4j vulnerability.

Figure: Log4Shell Unique IPs per hour, Source: GreyNoise Research

On December 5, 2021, Apache identified a vulnerability (later identified as CVE-2021-44228) in their widely used Log4j logging service. The vulnerability, also known as Log4shell, enables attackers to gain full control of affected servers by allowing unauthenticated remote code execution if the user is running an application utilizing the Java logging library. Log4j is heavily integrated into a broad set of devops frameworks, enterprise IT systems, and vendor software and cloud products.

GreyNoise first observed activity for this vulnerability on December 9, 2021 from 194.48.199[.]78 and 181.214.39[.]2.

Source: GreyNoise Research, Twitter (

To get a current list of all the IP addresses opportunistically scanning the internet to vuln check or exploit CVE-2021-44228, check out this tag summary in the GreyNoise Visualizer:

“The reason this vulnerability matters is that Log4j is heavily integrated in enterprise IT and devops. There are a whole bunch of devops frameworks and a whole bunch of enterprise IT systems and vendor systems that use it. So if you pick basically any large vendor and stick Log4j in Google, you’ll find it kicking around in different products, which is going to become a problem. There’s clearly lots of systems out there that, in some way shape or form, rely on this.” – Kevin Beaumont (@GossiTheDog, via Twitter Spaces recording)


On December 5th, 2021, Apache filed a JIRA issue identifying the vulnerability that would become CVE-2021-44228. The following day, December 6th, Apache released a patch providing some details on the vulnerability and crediting Chen Zhaojun of Alibaba Cloud Security Team for the discovery.

On December 9th, weaponized proof-of-concept exploits (PoCs) began to appear, leading to a rapid increase of scanning and public exploitation on December 10th.

Figure: Timeline of events leading up to GreyNoise observing CVE-2021-44228 in the wild. Source: GreyNoise Research

Between 1200 EST and 1400 EST on December 10, 2021, GreyNoise has observed a 5x increase in the number of hits per sensor related to the Log4shell event.

Figure: Hourly breakdown of traffic observed by GreyNoise sensors on 2021-12-09 to 2021-12-10. Source: GreyNoise Research

Impact of CVE-2021-44228

Due to ease of exploitation and prevalence of Log4J, GreyNoise researchers believe that this activity will continue to increase over the next few days. A wide variety of use cases for this exploit have already begun to appear, ranging from exploiting Minecraft servers

Figure: Exploiting Minecraft servers with the Apache Log4j vulnerability. Source:

to more high profile issues potentially affecting Apple iCloud

Figure: Exploiting Apple iCloud with the Apache Log4j vulnerability. Source:

The vulnerability feels similar to ShellShock, a vulnerability GreyNoise still observes since it was first identified in 2014.

Indicator of Compromise (IoC) resources for security teams

GreyNoise is providing IOCs for CVE-2021-44228 Apache Log4j RCE attempts on Github. You can access the C2/Callback domains here and the latest IPs here. You can get the most up to date information via GreyNoise for Log4shell here.

Figure: GreyNoise IOCs for CVE-2021-44228 Apache Log4j RCE attempts - C2/Callback domains. Source: GreyNoise Research

CVE-2021-44228 is still new and the impact of it will likely be felt for a long time, due to the pervasiveness of Log4j. Multiple recommendations for patching have been made (CISA, LunaSec) and detections have been made available. As the landscape develops, GreyNoise will be tweeting about new information and IoCs. Follow us there for the latest information.