First published: 08 Dec 2023
Last updated: 08 Dec 2023

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The Russia-based actor Star Blizzard (formerly known as SEABORGIUM, also known as Callisto Group/TA446/COLDRIVER/TAG-53/BlueCharlie) continues to successfully use spear-phishing attacks against targeted organisations and individuals in the UK, and other geographical areas of interest, for information-gathering activity.

The UK National Cyber Security Centre (NCSC), the US Cybersecurity and Infrastructure Security Agency (CISA), the US Federal Bureau of Investigation (FBI), the US National Security Agency (NSA), the US Cyber National Mission Force (CNMF), the Australian Signals Directorate’s Australian Cyber Security Centre (ASD’s ACSC), the Canadian Centre for Cyber Security (CCCS), and the New Zealand National Cyber Security Centre (NCSC-NZ) assess that Star Blizzard is almost certainly subordinate to the Russian Federal Security Service (FSB) Centre 18.

Industry has previously published details of Star Blizzard. This advisory draws on that body of information.

This advisory raises awareness of the spear-phishing techniques Star Blizzard uses to target individuals and organisations. This activity is continuing through 2023.

Targeting profile

Since 2019, Star Blizzard has targeted sectors including academia, defence, governmental organisations, NGOs, think-tanks and politicians.

Targets in the UK and US appear to have been most affected by Star Blizzard activity, however activity has also been observed against targets in other NATO countries, and countries neighbouring Russia.

During 2022, Star Blizzard activity appeared to expand further, to include defence-industrial targets, as well as US Department of Energy facilities.

Outline of the attacks

The activity is typical of spear-phishing campaigns, where an actor targets a specific individual or group using information known to be of interest to the targets. In a spear-phishing campaign, an actor perceives their target to have direct access to information of interest, be an access vector to another target, or both.

Research and preparation

Using open-source resources to conduct reconnaissance, including social media and professional networking platforms, Star Blizzard identifies hooks to engage their target. They take the time to research their interests and identify their real-world social or professional contacts. [T1589; T1593]

Star Blizzard creates email accounts impersonating known contacts of their targets to help appear legitimate. They also create fake social media or networking profiles that impersonate respected experts [T1585.001] and have used supposed conference or event invitations as lures.

Star Blizzard uses webmail addresses from different providers, including Outlook, Gmail, Yahoo and Proton mail in their initial approach [T1585.002], impersonating known contacts of the target or well-known names in the target’s field of interest or sector.

To appear authentic, the actor also creates malicious domains resembling legitimate organisations [T1583.001].

Microsoft Threat Intelligence Center (MSTIC) provides a list of observed Indicators of Compromise (IOCs) in their SEABORGIUM blog, but this is not exhaustive.

Preference for personal email addresses

Star Blizzard has predominantly sent spear-phishing emails to targets’ personal email addresses, although they have also used targets’ corporate or business email addresses. The actors may intentionally use personal emails to circumvent security controls in place on corporate networks.

Building a rapport

Having taken the time to research their targets’ interests and contacts to create a believable approach, Star Blizzard now starts to build trust. They often begin by establishing benign contact on a topic they hope will engage their targets. There is often some correspondence between attacker and target, sometimes over an extended period, as the attacker builds rapport.

Delivery of malicious link

Once trust is established, the attacker uses typical phishing tradecraft and shares a link [T1566.002], apparently to a document or website of interest. This leads the target to an actor-controlled server, prompting the target to enter account credentials.

The malicious link may be a URL in an email message, or the actor may embed a link in a document [T1566.001] on OneDrive, Google Drive, or other file-sharing platforms.

Star Blizzard uses the open-source framework EvilGinx in their spear-phishing activity, which allows them to harvest credentials and session cookies to successfully bypass the use of two-factor authentication [T1539; T1550.004].

Exploitation and further activity

Whichever delivery method is used, once the target clicks on the malicious URL, they are directed to an actor-controlled server that mirrors the sign-in page for a legitimate service. Any credentials entered at this point are now compromised.

Star Blizzard then uses the stolen credentials to log in to a target’s email account [T1078], from where they are known to access and steal emails and attachments from the victim’s inbox [T1114.002]. They have also set up mail-forwarding rules, giving them ongoing visibility of victim correspondence [T1114.003].

The actor has also used their access to a victim email account to access mailing-list data and victim’s contacts lists, which they then use for follow-on targeting. They have also used compromised email accounts for further phishing activity [T1586.002].


Spear-phishing is an established technique used by many actors, and Star Blizzard uses it successfully, evolving the technique to maintain their success.

Individuals and organisations from previously targeted sectors should be vigilant of the techniques described in this advisory.

In the UK you can report related suspicious activity to the NCSC.

Information on effective defence against spear-phishing is included in the ‘Mitigation’ section below.


This report has been compiled with respect to the MITRE ATT&CK® framework, a globally accessible knowledge base of adversary tactics and techniques based on real-world observations.

Tactic ID Technique Procedure
Reconnaissance T1593 Search Open Websites/Domains Star Blizzard uses open-source research and social media to identify information about victims to use in targeting.
Reconnaissance T1589 Gather Victim Identity Information Star Blizzard uses online data sets and open-source resources to gather information about their targets.
Resource Development T1585.001 Establish Accounts: Social Media Accounts Star Blizzard has been observed establishing fraudulent profiles on professional networking sites to conduct reconnaissance.
Resource Development T1585.002 Establish Accounts: Email Accounts Star Blizzard registers consumer email accounts matching the names of individuals they are impersonating to conduct spear-phishing activity.
Resource Development T1583.001 Acquire Infrastructure: Domains Star Blizzard registers domains to host their phishing framework.
Resource Development T1586.002 Compromise Accounts: Email Accounts Star Blizzard has been observed using compromised victim email accounts to conduct spear-phishing activity against contacts of the original victim.
Initial Access T1078 Valid Accounts Star Blizzard uses compromised credentials, captured from fake log-in pages, to log in to valid victim user accounts.
Initial Access T1566.001 Phishing: Spear-phishing Attachment Star Blizzard uses malicious links embedded in email attachments to direct victims to their credential-stealing sites.
Initial Access T1566.002 Phishing: Spear-phishing Link Star Blizzard sends spear-phishing emails with malicious links directly to credential-stealing sites, or to documents hosted on a file-sharing site, which then direct victims to credential-stealing sites.
Defence Evasion T1550.004 Use Alternate Authentication Material: Web Session Cookie Star Blizzard bypasses multi-factor authentication on victim email accounts by using session cookies stolen using EvilGinx.
Credential Access T1539 Steal Web Session Cookie Star Blizzard uses EvilGinx to steal the session cookies of victims directed to their fake log-in domains.
Collection T1114.002 Email Collection: Remote Email Collection Star Blizzard interacts directly with externally facing Exchange services, Office 365 and Google Workspace to access email and steal information using compromised credentials or access tokens.
Collection T1114.003 Email Collection: Email Forwarding Rule Star Blizzard abuses email-forwarding rules to monitor the activities of a victim, steal information, and maintain persistent access to victim's emails, even after compromised credentials are reset.


A number of mitigations will be useful in defending against the activity described in this advisory.


This report draws on information derived from NCSC and industry sources. Any NCSC findings and recommendations made have not been provided with the intention of avoiding all risks and following the recommendations will not remove all such risk. Ownership of information risks remains with the relevant system owner at all times.

This information is exempt under the Freedom of Information Act 2000 (FOIA) and may be exempt under other UK information legislation.

Refer any FOIA queries to

All material is UK Crown Copyright ©

Updated advisory: Microsoft released a new advisory for Star Blizzard activity on the 7th of December. The new advisory has updated mitigation advice and IOCs in response to the threat actor's tradecraft evolution.

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