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).

Correlation Search

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 ("*Cmdline Tool Not Executed In CMD Shell*", "*Windows System Network Config Discovery Display DNS*", "*Local Account Discovery With Wmic*", "*Net Localgroup Discovery*", "*Create local admin accounts using net exe*", "*Local Account Discovery with 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, Subvert Trust Controls	TTP
Attempt To Stop Security Service	Disable or Modify Tools, Impair Defenses	TTP
Processes launching netsh	Disable or Modify System Firewall, Impair Defenses	Anomaly
Sc exe Manipulating Windows Services	Windows Service, Create or Modify System Process	TTP
Suspicious Reg exe Process	Modify Registry	Anomaly
Unload Sysmon Filter Driver	Disable or Modify Tools, Impair Defenses	TTP

Data Sources

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

References

Source: GitHub | Version: 2