Email Addresses
Adversaries may gather email addresses that can be used during targeting. Even if internal instances exist, organizations may have public-facing email infrastructure and addresses for employees. Adversaries may easily gather email addresses, since they may be readily available and exposed via online or other accessible data sets (ex: Social Media or Search Victim-Owned Websites). Email addresses could also be enumerated via more active means (i.e. Active Scanning), such as probing and analyzing responses from authentication services that may reveal valid usernames in a system. For example, adversaries may be able to enumerate email addresses in Office 365 environments by querying a variety of publicly available API endpoints, such as autodiscover and GetCredentialType. Gathering this information may reveal opportunities for other forms of reconnaissance (ex: Search Open Websites/Domains or Phishing for Information), establishing operational resources (ex: Email Accounts), and/or initial access (ex: Phishing or Brute Force via External Remote Services).
Open detection, hunting, mitigation, and evidence workspace
Detection logic
Monitor for suspicious network traffic that could be indicative of probing for email addresses and/or usernames, such as large/iterative quantities of authentication requests originating from a single source (especially if the source is known to be associated with an adversary/botnet). Analyzing web metadata may also reveal artifacts that can be attributed to potentially malicious activity, such as referer or user-agent string HTTP/S fields. Much of this activity may have a very high occurrence and associated false positive rate, as well as potentially taking place outside the visibility of the target organization, making detection difficult for defenders. Detection efforts may be focused on related stages of the adversary lifecycle, such as during Initial Access.
Observed actors
Correlated CTI and IR reports
1200km CTI repository · explicit report mentionAttack Playbook — Operation DragonRx
1200km CTI repository · explicit report mentionOperation DragonRx — APT41 Full Attack Simulation
1200km CTI repository · explicit report mentionOperation DragonRx: Simulating an APT41 Attack End-to-End — From Log4Shell to DFIR and Malware Analysis
1200km CTI repository · explicit report mentionAPT41 Targeting Pharmaceutical Sector Log4Shell to Domain Compromise
1200km Medium · authored report mentionAttack Playbook Operation DragonRx
1200km Medium · authored report mentionOperation DragonRx Simulating an APT41 Attack End to End From Log4Shell to DFIR and Malware
1200km Medium · authored report mention