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On May 28, 2020, the United States National Security Agency (NSA) released a Cyber Security Advisory that warned of a Russian Espionage campaign associated with the Sandworm group that was actively exploiting vulnerabilities in the Exim mail transfer agent.

The vulnerabilities leveraged impact Exim Internet Mailer version 4.87 – 4.92. Searching RiskIQ’s internet intelligence database, from May 1, 2020, RiskIQ has observed over 900K vulnerable Exim instances.

A Russian Espionage campaign is exploiting vulnerabilities in the Exim mail servers. RiskIQ sees patching on the rise, but 900k+ instances remain online.

We can break down this data into daily observations of versions detected for May. As the graph below shows, RiskIQ has observed a gradual decrease in observed daily vulnerable instances, indicating that organizations are upgrading their Exim mail servers.

A Russian Espionage campaign is exploiting vulnerabilities in the Exim mail servers. RiskIQ sees patching on the rise, but 900k+ instances remain online.

The advisory recommends that organizations running vulnerable instances upgrade to the latest version Exim Internet Mailer (version 4.93) immediately. In the chart below, we highlight patching trends observed globally over the past month for Exim systems.

A Russian Espionage campaign is exploiting vulnerabilities in the Exim mail servers. RiskIQ sees patching on the rise, but 900k+ instances remain online.

Vulnerable versions of Exim are noted in green above, while patched versions (those running Exim 4.93) are showing in orange. Again, we can see a gradual trend of daily vulnerable instances decreasing while patched instances are increasing.

RiskIQ customers can get visibility into their exposure to this threat through RiskIQ’s Attack Intelligence dashboard available in our Digital Footprint product.

A Russian Espionage campaign is exploiting vulnerabilities in the Exim mail servers. RiskIQ sees patching on the rise, but 900k+ instances remain online.

While the NSA Advisory only calls out CVE-2019-10149 by name, there were three critical vulnerabilities announced in 2019 involving remote code/command execution (RCE). All three were leveraged in this broader attack campaign.

  • CVE-2019-10149: This vulnerability allows attackers to execute remote commands on impacted systems as root. It was discovered in June 2019 and affects Exim versions 4.87 to 4.91.
  • CVE-2019-15846: is a remote code execution vulnerability that allows an attacker to run programs on a system with full root privileges. It was initially reported in July 2019 and patched in September 2019. It affected Exim versions up to and including 4.92.1.
  • CVE-2019-16928: is a heap-based overflow vulnerability that can allow denial of service or remote code execution attacks and affected Exim versions 4.92 through 4.92.2. The Exim Maintainers released a patch (in addition to the one associated with CVE-2019-15846) in September 2019. It was included in Exim version 4.92.3.

Additionally, the NSA released a few IOCs associated with this recent Sandworm activity. These IOCs are available for further investigations in this RiskIQ PassiveTotal community.

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A modern organization’s digital presence is a mosaic of internet-connected services—hardware, software, and digital supply chains. More internet services mean complexity goes up, and “non-standard” becomes the norm. However, while these digital services boost functionality, they can also unexpectedly change how organizations appear to attackers and, at any time, open up exposures across an attack surface. Just recently, the massive boost in VPN and remote access to enable staff forced to work from home has created an array of new access points for attackers to interrogate.

With your attack surface regularly in flux, keeping tabs on its composition as well as the infrastructure of attackers targeting it is one of the most challenging jobs facing security teams today. However, deep insight across the public internet makes it not only possible but also manageable. 

RiskIQ collects data at an unmatched scale. Our systems conduct daily scanning of ports and service banners across the entire IPv4 space to collect host data, including when it was first and last seen, service banners, and much more. These observations are saved within the RiskIQ Internet Intelligence Graph and made available to customers.

Explore RiskIQ’s exposed services data set in RiskIQ PassiveTotal, and learn how RiskIQ can help you discover and protect your attack surface today.

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