T1534 - Internal Spearphishing#

Adversaries may use internal spearphishing to gain access to additional information or exploit other users within the same organization after they already have access to accounts or systems within the environment. Internal spearphishing is multi-staged campaign where an email account is owned either by controlling the user’s device with previously installed malware or by compromising the account credentials of the user. Adversaries attempt to take advantage of a trusted internal account to increase the likelihood of tricking the target into falling for the phish attempt.(Citation: Trend Micro When Phishing Starts from the Inside 2017)

Adversaries may leverage Spearphishing Attachment or Spearphishing Link as part of internal spearphishing to deliver a payload or redirect to an external site to capture credentials through Input Capture on sites that mimic email login interfaces.

There have been notable incidents where internal spearphishing has been used. The Eye Pyramid campaign used phishing emails with malicious attachments for lateral movement between victims, compromising nearly 18,000 email accounts in the process.(Citation: Trend Micro When Phishing Starts from the Inside 2017) The Syrian Electronic Army (SEA) compromised email accounts at the Financial Times (FT) to steal additional account credentials. Once FT learned of the campaign and began warning employees of the threat, the SEA sent phishing emails mimicking the Financial Times IT department and were able to compromise even more users.(Citation: THE FINANCIAL TIMES LTD 2019.)

Atomic Tests:#

Currently, no tests are available for this technique.

Detection#

Network intrusion detection systems and email gateways usually do not scan internal email, but an organization can leverage the journaling-based solution which sends a copy of emails to a security service for offline analysis or incorporate service-integrated solutions using on-premise or API-based integrations to help detect internal spearphishing campaigns.(Citation: Trend Micro When Phishing Starts from the Inside 2017)

Shield Active Defense#

User Training#

Train users to detect malicious intent or activity, how to report it, etc.

User training involves teaching end users to be human sensors who know how to recognize cyber threats and the procedures for reporting them. Users can be effective sensors for social engineering attempts, phishing email detection, as well as other cyber threats.

Opportunity#

There is an opportunity to detect the presence of an adversary by identifying and alerting on anomalous behaviors.

Use Case#

A program to train users to report emails that they did not send but appear in their sent folder.

Procedures#

Train users to immediately report suspicious emails. Those emails could then be used for malware detonation or adversary engagement purposes. Train users to report potentially compromised devices so they can be isolated or migrated into deception networks.