Earth Krahang Exploits Intergovernmental Trust to Launch Cross-Government Attacks – Trend Micro

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Government organizations seem to be Earth Krahang’s primary targets. As an example, in the case of one country, we found that the threat actor compromised a diverse range of organizations belonging to 11 different government ministries.

We found that at least 48 government organizations were compromised, with a further 49 other government entities being targeted. Foreign Affairs ministries and departments were a top target, compromising 10 such organizations and targeting five others.

Education is another sector of interest to the threat actor. We found at least two different victims and 12 targets belonging to this sector. The communications industry was also targeted; we found multiple compromised telecommunications providers. Other target organizations and entities include post offices (targeted in at least three different countries), logistics platforms, and job services.

There were other industries targeted, but on a smaller scale, including the following:

  • Finance/Insurance
  • Foundations/NGOs/Thinkthanks
  • Healthcare
  • IT
  • Manufacturing
  • Media
  • Military
  • Real estate
  • Retail
  • Sports
  • Tourism

Attribution

Initially, we had no attribution for this campaign since we found no infrastructure overlaps, and had never seen the RESHELL malware family before. Palo Alto published a report that attributes, with moderate confidence, a particular cluster using RESHELL malware to GALLIUM. However, the assessment is based on a toolset that is shared among many different threat actors, and we were hesitant to use this link for proper attribution.  We also considered the possibility that RESHELL is a shared malware family.

Earth Krahang switched to the XDealer malware family in later campaigns. In a research paper presented by TeamT5, XDealer was shown to be associated with Luoyu, a threat actor with Chinese origins that used the WinDealer and ReverseWindow malware families. Our colleague, who was previously involved in the research of Luoyu, shared with us the insights on this association, particularly the sharing of an encryption key between an old XDealer sample and a SpyDealer sample — suggesting a connection between both malware families. ESET, which named this malware DinodasRAT, wrote an extensive report on its features. However they had no particular attribution apart from the possible China-nexus origin.

While we believe it could be possible that this campaign has links to LuoYu, we found no traces of other malware families used by this threat actor. Also, the encryption key mentioned above is different from the samples we found in this campaign, meaning that this malware family has multiple builders. This could suggest that either the key was changed at some point in development, or that the tool is shared among different groups.

In January 2022, we reported on a China-nexus threat actor we called Earth Lusca, following up with updates on their use of a newly discovered backdoor named SprySOCKS and their recent activities capitalizing on the Taiwanese presidential election. During our investigation, we noticed malware being downloaded from IP addresses we attribute to Earth Lusca (45[.]32[.]33[.]17 and 207[.]148[.]75[.]122, for example) at the lateral movement stage of this campaign. This suggests a strong link between this threat actor and Earth Lusca. We also found infrastructure overlaps between some C&C servers that communicated with malware we found during our investigation, and domain names such as googledatas[.]com that we attribute to Earth Lusca.

While the infrastructure and the preference of the initial stage backdoors look to be very different between this new campaign and the previously reported activities of Earth Lusca, our speculation is that they are two intrusion sets running independently but targeting a similar range of victims, becoming more intertwined as they approach their goal — possibly even being  managed by the same threat group. Due to these characteristics, we decided to give the independent name, Earth Krahang, to this intrusion set.

Our previous report suggests Earth Lusca might be the penetration team behind the Chinese company I-Soon, which had their information leaked on GitHub recently. Using this leaked information, we found that the company organized their penetration team into two different subgroups. This could be the possible reason why we saw two independent clusters of activities active in the wild but with limited association. Earth Krahang could be another penetration team under the same company.

Conclusion

In this report, we shared our investigation on a new campaign we named Earth Krahang. Our findings show that this threat actor focuses its efforts on government entities worldwide and abuses compromised government infrastructure to enable its malicious operations.

We were also able to identify two unique malware families used in Earth Krahang’s attacks while also illustrating the larger picture involving the group’s targets and malicious activities via our telemetry data and the exposed files on their servers.

Our investigation also identified multiple links between Earth Krahang and Earth Lusca. We suspected these two intrusion sets are managed by the same threat actor.

Given the importance of Earth Krahang’s targets and their preference of using compromised government email accounts, we strongly advise organizations to adhere to security best practices, including educating employees and other individuals involved with the organization on how to avoid social engineering attacks, such as developing a healthy skepticism when it involves potential security issues, and developing habits such as refraining from clicking on links or opening attachments without verification from the sender. Given the threat actor’s exploitation of vulnerabilities in its attacks, we also encourage organizations to update their software and systems with the latest security patches to avoid any potential compromise.

Indicators of Compromise

The indicators of compromise for this entry can be found here.

Acknowledgment

Special thanks to Leon M Chang who shared to us insights about the overlap of  the TEA encryption key between XDealer and SpyDealer samples.

This post was originally published on the 3rd party site mentioned in the title of this this site

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