APT36 Spreads Fake Coronavirus Health Advisory Delivers Crimson RAT

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APT36 spreads fake coronavirus health advisory

APT36 mainly relies on both spear phishing and watering hole attacks to gain its foothold on victims. The phishing email is either a malicious macro document or an rtf file exploiting vulnerabilities, such as CVE-2017-0199.

In the coronavirus-themed attack, APT36 used a spear phishing email with a link to a malicious document (Figure 1) masquerading as the government of India ( email.gov.in.maildrive[.]email/?att=1579160420 ).

Figure 1: Phishing document containing malicious macro code

Figure 2: malicious macro

Based on the OS type, the macro picks either a 32bit or 64bit version of its RAT payload in zip format that is stored in one of the two textboxes in UserForm1 (Figure 3).

Figure 3: embedded payloads in ZIP format

Crimson RAT

The Crimson RAT has been written in .Net (Figure 4) and its capabilities include:

  • Stealing credentials from the victim’s browser
  • Listing running processes, drives, and directories on the victim’s machine
  • Retrieving files from its C&C server
  • Using custom TCP protocol for its C&C communications
  • Collecting information about antivirus software
  • Capturing screenshots

Figure 4: Crimson RAT

Upon running the payload, Crimson RAT connects to its hardcoded C&C IP addresses and sends collected information about the victim back to the server, including a list of running processes and their IDs, the machine hostname, and its username (Figure 5).

Figure 5: TCP communications

Indicators of Compromise

Decoy URLs

email.gov.in.maildrive[.]email/?att=1579160420
email.gov.in.maildrive[.]email/?att=1581914657

Decoy documents

876939aa0aa157aa2581b74ddfc4cf03893cede542ade22a2d9ac70e2fef1656
20da161f0174d2867d2a296d4e2a8ebd2f0c513165de6f2a6f455abcecf78f2a

Crimson RAT

0ee399769a6e6e6d444a819ff0ca564ae584760baba93eff766926b1effe0010 b67d764c981a298fa2bb14ca7faffc68ec30ad34380ad8a92911b2350104e748

C2s

107.175.64[.]209 64.188.25[.]205

MITRE ATT&CK

https://attack.mitre.org/software/S0115/

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