Analytics Story: Disabling Security Tools

Date: 2020-02-04 ID: fcc27099-46a0-46b0-a271-5c7dab56b6f1 Author: Rico Valdez, Splunk Product: Splunk Enterprise Security

Description

Looks for activities and techniques associated with the disabling of security tools on a Windows system, such as suspicious reg.exe processes, processes launching netsh, and many others.

Why it matters

Attackers employ a variety of tactics in order to avoid detection and operate without barriers. This often involves modifying the configuration of security tools to get around them or explicitly disabling them to prevent them from running. This Analytic Story includes searches that look for activity consistent with attackers attempting to disable various security mechanisms. Such activity may involve monitoring for suspicious registry activity, as this is where much of the configuration for Windows and various other programs reside, or explicitly attempting to shut down security-related services. Other times, attackers attempt various tricks to prevent specific programs from running, such as adding the certificates with which the security tools are signed to a block list (which would prevent them from running).

1| tstats `security_content_summariesonly` min(_time) as firstTime max(_time) as lastTime sum(All_Risk.calculated_risk_score) as risk_score, count(All_Risk.calculated_risk_score) as risk_event_count, values(All_Risk.annotations.mitre_attack.mitre_tactic_id) as annotations.mitre_attack.mitre_tactic_id, dc(All_Risk.annotations.mitre_attack.mitre_tactic_id) as mitre_tactic_id_count, values(All_Risk.annotations.mitre_attack.mitre_technique_id) as annotations.mitre_attack.mitre_technique_id, dc(All_Risk.annotations.mitre_attack.mitre_technique_id) as mitre_technique_id_count, values(All_Risk.tag) as tag, values(source) as source, dc(source) as source_count from datamodel=Risk.All_Risk where source IN ("*Windows Cmdline Tool Execution From Non-Shell Process*", "*Windows System Network Config Discovery Display DNS*", "*Local Account Discovery With Wmic*", "*Windows Group Discovery Via Net*", "*Windows Create Local Administrator Account Via Net*", "*Windows User Discovery Via Net*", "*Icacls Deny Command*", "*ICACLS Grant Command*", "*Windows Proxy Via Netsh*", "*Processes launching netsh*", "*Disabling Firewall with Netsh*", "*Windows System Network Connections Discovery Netsh*", "*Network Connection Discovery With Arp*", "*Windows System Discovery Using ldap Nslookup*", "*Windows System Shutdown CommandLine*") by All_Risk.risk_object All_Risk.risk_object_type All_Risk.annotations.mitre_attack.mitre_tactic | `drop_dm_object_name(All_Risk)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | where source_count >= 4 | `windows_common_abused_cmd_shell_risk_behavior_filter`

Detections

Name ▲▼ Technique ▲▼ Type ▲▼
Attempt To Add Certificate To Untrusted Store Install Root Certificate TTP
Processes launching netsh Disable or Modify System Firewall Anomaly
Sc exe Manipulating Windows Services Windows Service TTP
Suspicious Reg exe Process Modify Registry Anomaly
Unload Sysmon Filter Driver Disable or Modify Tools TTP
Windows Attempt To Stop Security Service Disable or Modify Tools TTP

Data Sources

Name ▲▼ Platform ▲▼ Sourcetype ▲▼ Source ▲▼
CrowdStrike ProcessRollup2 N/A crowdstrike:events:sensor crowdstrike
Sysmon EventID 1 Windows icon Windows xmlwineventlog XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
Windows Event Log Security 4688 Windows icon Windows xmlwineventlog XmlWinEventLog:Security

References

Source: GitHub | Version: 2