Multiple Alerts in Same ATT&CK Tactic by Host

This detection rule correlates multiple security alerts associated with the same ATT&CK tactic on a single host within a defined time window (60 minutes). The purpose of this rule is to identify hosts exhibiting concentrated malicious behavior, which may indicate an active intrusion or post-compromise activity. This allows analysts to prioritize triage towards hosts with a higher likelihood of compromise. The rule specifically excludes noisy tactics such as Discovery, Persistence, and Lateral Movement, focusing instead on tactics like Credential Access, Defense Evasion, Execution, and Command and Control. It requires at least three unique detection rules to trigger, ensuring that the activity is not a single, isolated event. The rule also excludes alerts generated by Machine Learning and Threat Match rules, as well as some noisy rules such as “Agent Spoofing - Mismatched Agent ID” and “Process Termination followed by Deletion”.

Attack Chain

1. Initial Access: An attacker gains initial access to a host through methods like exploiting a vulnerability or using stolen credentials.
2. Execution: The attacker executes malicious code on the compromised host, potentially using tools like PowerShell or cmd.exe.
3. Defense Evasion: The attacker attempts to evade detection by disabling security controls or obfuscating their actions.
4. Credential Access: The attacker attempts to steal credentials from the compromised host, such as passwords or Kerberos tickets.
5. Command and Control: The attacker establishes a command and control channel to communicate with the compromised host.
6. Further Exploitation: The attacker uses the compromised host to move laterally within the network, potentially targeting other systems or data.
7. Data Exfiltration or Impact: The attacker exfiltrates sensitive data from the network or causes damage to systems.

Impact

A successful attack can lead to significant data breaches, financial losses, and reputational damage. By identifying hosts exhibiting multiple alerts related to the same ATT&CK tactic, organizations can proactively respond to potential intrusions before they escalate into more serious incidents. Failure to detect and respond to these types of attacks can result in widespread compromise and significant disruption to business operations.

Recommendation

• Deploy the Sigma rule provided in this brief to your SIEM to detect hosts exhibiting multiple alerts within the same ATT&CK tactic. Tune the rule to your environment to reduce false positives.
• Investigate hosts that trigger the Sigma rule to determine the root cause of the alerts and take appropriate remediation steps.
• Review and update your existing detection rules to ensure they are effective at detecting the latest threats and tactics.
• Enable logging for process creation, network connections, and file modifications to provide more visibility into host activity and improve detection capabilities.
• Implement a vulnerability management program to identify and patch vulnerabilities on your systems to prevent attackers from gaining initial access.