Pierluigi Paganini January 14, 2021

Security experts from ESET uncovered an ongoing surveillance campaign, dubbed Operation Spalax, against Colombian government institutions and private companies.

Malware researchers from ESET uncovered an ongoing surveillance campaign, dubbed Operation Spalax, against Colombian entities exclusively.

The attacks aimed at government institutions and private companies, most of them in the energy and metallurgical sectors.  The campaign has been active at least since 2020, the attackers leverage remote access trojans to spy on their victims. 

The attacks share some similarities with other campaigns targeting Colombian entities, in particular a campaign detailed in February 2019, by QiAnXin. The operations described by QiAnXin are attributed to an APT group active since at least April 2018.

Below the similarities found by ESET:

• We saw a malicious sample included in IoCs of QiAnXin’s report and a sample from the new campaign in the same government organization. These files have fewer than a dozen sightings each.
• Some of the phishing emails from the current campaign were sent from IP addresses corresponding to a range that belongs to Powerhouse Management, a VPN service. The same IP address range was used for emails sent in the earlier campaign.
• The phishing emails have similar topics and pretend to come from some of the same entities – for example, the Office of the Attorney General (Fiscalia General de la Nacion) or the National Directorate of Taxes and Customs (DIAN).
• Some of the C&C servers in Operation Spalax use linkpc.net and publicvm.com subdomains, along with IP addresses that belong to Powerhouse Management. This also happened in the earlier campaign.

However, experts found differences in the attachments used for phishing emails, the remote access trojans (RATs) used the operator’s C&C infrastructure.

The attacks start with phishing messages that lead to the download of RAR archives hosted on OneDrive or MediaFire containing a malicious executable.

“We’ve found a variety of packers used for these executables, but their purpose is always to have a remote access trojan running on the victimized computer, usually by decrypting the payload and injecting it into legitimate processes.” continues the report. “We have seen the attackers use three different RATs: Remcos, njRAT and AsyncRAT.”

The phishing messages used a wide range of topics as lures, such as notifications of driving infractions, to attend court hearings, and to take mandatory COVID-19 tests.

ESET also documented the use of heavily obfuscated AutoIt droppers, in this attack scenario the first-stage malware performs the injection and execution of the payload. The malware use two shellcodes contained in the compiled AutoIt script, the first one decrypts the payload and the second injects it into some process.

The Trojans used in Operation Spalax implements several capabilities to spy on targets, such as keylogging, screen capture, clipboard hijacking, exfiltration of files, and the ability to download and execute other payloads.

ESET pointed out that the attackers leveraged on large network C2 infrastructure, experts observed at least 24 different IP addresses in use in the second half of 2020. Attackers probably compromised devices to use them as proxies for their C2 servers. The threat actors also used dynamic DNS services to manage a pool of 70 different domain names (and also register new ones on a regular basis) that are dynamically assigned to IP addresses. In the second half of 2020 alone they used 24 IP addresses.

“Targeted malware attacks against Colombian entities have been scaled up since the campaigns that were described last year,” ESET concludes. “The landscape has changed from a campaign that had a handful of C2 servers and domain names to a campaign with very large and fast-changing infrastructure with hundreds of domain names used since 2019.”

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Pierluigi Paganini

(SecurityAffairs – hacking, Operation Spalax)

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