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CMSTAR Downloader Malware

Two new variants of the CMSTAR downloader malware have been discovered containing two new previously unseen backdoors named, BYEBY and PYLOT. These have recently been used in a phishing campaigns.
Threat ID:
CC-1677
Category:
Threat Severity:
Medium
Threat Vector:
Phishing
Published:
5 October 2017 12:00 AM
Report a cyber attack: call 0300 303 5222 or email [email protected]

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This article no longer conforms to NHS Digital's standards for cyber alerts, and may contain outdated or inaccurate information. Use of this information contained in this page is at your own risk

Summary

Two new variants of the CMSTAR downloader malware have been discovered containing two new previously unseen backdoors named, BYEBY and PYLOT. These have recently been used in a phishing campaigns.

Affected platforms

The following platforms are known to be affected:

Microsoft Windows

Microsoft Windows - All Versions

Threat details

The malware is spread though phishing emails containing a number of decoy documents and folders including jpeg images. If the attachments are opened the malicious CMSTAR payload is dropped including the PYLOT and BYEBYE backdoors.

Remediation steps

Type Step
  • 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, antivirus and other security products are kept up to date.
  • All day to day computer activities such as email and internet are performed using non-administrative accounts.
  • Strong password policies are in place and password reuse is discouraged.
  • Network, proxy and firewall logs should be monitored for suspicious activity.

Last edited: 17 February 2020 11:29 am