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Okrum Backdoor

Okrum is a simple backdoor created by the Ke3chang (also known as APT15) advanced persistent threat. First observed in 2016 in campaigns against Eastern European government organisations, Ke3chang now uses Okrum against targets globally.

Threat ID:
CC-3161
Category:
Backdoor
Threat Severity:
Medium
Threat Vector:
Published:
23 July 2019 12:00 AM
Report a cyber attack: call 0300 303 5222 or email [email protected]

Summary

Okrum is a simple backdoor created by the Ke3chang (also known as APT15) advanced persistent threat. First observed in 2016 in campaigns against Eastern European government organisations, Ke3chang now uses Okrum against targets globally.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All versions

Threat details

At the time of publication, Okrum is delivered as an encrypted Dynamic-link Library file embedded within a PNG image file, with Ke3chang making extensive use of steganographic techniques to avoid detection. This file is decrypted and executed by an unnamed preliminary installer, likely a variant of the MirageFox remote access trojan.

Once installed, Okrum escalates its privileges by calling the ImpersonateLoggedOnUser API before collecting user, system, and network information and sending it to a command and control server over HTTP. As stated previously, Okrum is not technically complex and can only execute shell commands by default. However, Ke3chang are able to leverage this capability to install their own tools including the Ketrican, RoyalCLI, and RoyalDNS, as well as to execute third-party applications present on the affected system.

For further information:

Remediation steps

Type Step

To prevent and detect an infection, ensure that:

  • A robust program of education and awareness training is delivered to users to ensure they don’t open attachments or follow links within unsolicited emails.
  • All operating systems, anti-virus and other security products are kept up-to-date.
  • Regular anti-virus and security scans are performed on your organisation’s estate.
  • All day-to-day computer activities such as email and internet are performed using non-administrative accounts.
  • Strong password policies are in place.
  • Network, proxy and firewall logs should be monitored for suspicious activity.
  • User accounts accessed from affected devices should be reset on a clean computer.
  • Your organisation adopts a holistic all-round approach to Cyber Security as advocated by the 10 Steps to Cyber Security.

Last edited: 14 February 2020 2:51 pm