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How Internet Noise Makes Security Harder

The GreyNoise Team

Defining Internet Noise

Every machine connected to the internet is exposed to a constant barrage of communications from tens of thousands of unique IP addresses per day. A percentage of these communications are malicious attacks and web crawls; some are non-malicious scans and pings;  some are legitimate business services; and still others are unknown. Taken together, this massive volume of unsolicited traffic is a challenge for security organizations, because these communications trigger security tools to generate thousands of events to be analyzed, with little context on the potential threats.

Sources of Internet Noise

Let’s take a look at the different kinds of internet communications traffic that creates this “noise” for security organizations:

Internet Scanners (aka Internet Background Noise)

Scanning the internet means reaching out and trying to initiate communications with a wide range of devices  that are directly connected to the internet. At a technical level, mass scanning the internet means requesting a slight amount of information (specifically a TCP SYN, UDP/ICMP packet, or banner grab) from all 4.2 BILLION IP addresses on the entire routable IPv4 space. And it turns out that tens of thousands of devices are scanning the internet constantly, generating a tremendous amount of internet “noise”.

Who scans the Internet?

Good guys scan the internet to measure the exposure of vulnerabilities, take inventory of software market share, and find botnet command & control servers.  In fact, there are entire websites and companies that act as "search engines" devoted to mass scanning the internet. Examples of this include companies like Shodan and Censys, as well as researchers and universities, who scan in good faith to help uncover vulnerabilities for network defense.

Bad guys scan the internet with malicious intent,  to find vulnerable devices that they can compromise and use for nefarious purposes. So while benign mass-scanner IP addresses might check if a port is running and then go away, malicious scanners might attempt to compromise the target machine by brute-forcing login credentials or launching a remote exploit. A good example was a recently discovered vulnerability in F5 network devices - in this case, malicious IPs scanned for F5 BIG-IP devices, checked if the device was vulnerable, and attempted to exploit the vulnerability.

Unknown groups scan the internet for unclear or covert reasons. Unknown actors could be individual researchers, companies or nation state actors that are attempting to remain anonymous, and everything in between.

At the end of the day, web crawlers, port scanners, researchers, and malware such as worms and botnets are all part of the activities  that contribute to Internet Noise. The challenge for security organizations is differentiating which of these scans are malicious signs of a targeted attack, and which are just “noise”.

Common Business Services

Another increasingly challenging source of Internet Noise is legitimate network communications with common business applications like Microsoft O365, Google Workspace, and Slack, as well as services like CDNs and public DNS servers. These applications often communicate through unpublished or dynamic IPs, making them difficult to identify. The result is a storm of log events from “unknown” IP addresses that are, in reality, from well known and benign business services. Without context, this harmless communication distracts security teams from investigating true threats.

Security Challenges of Internet Noise

The goal for security teams is to identify malicious internet traffic that represents a potential threat to the organization, so they can focus research and remediation efforts quickly. Internet Noise ends up being a huge tax on SOC teams by taking time away from analysts that could be spent addressing true threats,  inflating log volumes and increasing storage costs, and contributing to analyst burnout.

GreyNoise Identifies Internet Noise So Security Teams Can Focus on Targeted Threats

GreyNoise tracks two distinct sets of Internet Noise today, making them available through our API, integrations and visualizer:

  • Internet Background Noise: At GreyNoise, we deploy and manage hundreds of servers in multiple data centers and countries around the world to listen to internet Background Noise. Our purpose is to sit back and soak up all the opportunistic traffic generated by anyone mass scanning the internet. GreyNoise analyzes and enriches this data to identify behavior, methods and intent. The goal is to give analysts the context they need to answer questions like: How many people are scanning the internet right now? What IP addresses is it coming from? What are they scanning for?
  • RIOT (“Rule It Out”): RIOT provides context to communications between your users and common business applications (e.g. Microsoft O365, Google Workspace and Slack), or services like CDNs and public DNS servers. These applications communicate through unpublished or dynamic IPs making it difficult for security teams to track. Without context, this harmless behavior distracts security teams from investigating true threats.

The data GreyNoise collects can be used by security analysts to identify and de-prioritize traffic from omnidirectional scanners and common business services, allowing them to focus on targeted scan and attack traffic. They can use the data to

  • track opportunistic botnets other compromised devices
  • understand what software vulnerabilities the bad guys are actively scanning for
  • automatically enrich and prioritize alerts in SIEM and SOAR systems
  • And, if so inclined, opt out of many malicious mass-scanners altogether by blocking them preemptively and dynamically at the firewall.

Viewing Internet Noise with GreyNoise

If you’re interested in learning more about what Internet Noise is, and how much of it is happening on the internet right now, please check out the GreyNoise Visualizer. Free to use, the Visualizer can show you:

  • Overall volume of Internet Noise
  • New IPs generating Internet Noise
  • Classification of Internet Noise into malicious, benign, and unknown actors
  • Top organizations that are sources of Internet Noise
  • Trends and anomalies in Internet Noise traffic over the past month
  • Detailed behavioral information about specific IP addresses running scans
  • Emerging threat data about vulnerabilities being actively exploited

And if you find this information interesting or useful, please sign up for a free Community account, which includes access to our API for a subset of the “noise” data we collect. Our community of 10,000+ security analysts is a tremendous source of insight about Internet Noise and other InfoSec knowledge. If you are interested in joining, please reach out to community@greynoise.io

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