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https://github.com/splunk/security_content
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Michael Haag
57 lines
3.9 KiB
YAML
57 lines
3.9 KiB
YAML
name: ProxyShell ProxyNotShell Behavior Detected
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id: c32fab32-6aaf-492d-bfaf-acbed8e50cdf
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version: 1
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date: '2022-10-03'
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author: Michael Haag, Splunk
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type: Correlation
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datamodel:
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- Risk
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description: The following correlation will identify activity related to Windows Exchange being actively exploited by adversaries related to ProxyShell or ProxyNotShell. In addition, the analytic correlates post-exploitation Cobalt Strike analytic story. Common post-exploitation behavior has been seen in the wild includes adversaries running nltest, Cobalt Strike, Mimikatz and adding a new user. The correlation specifically looks for 5 distinct analyticstories to trigger. Modify or tune as needed for your organization.
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5 analytics is an arbitrary number but was chosen to reduce the amount of noise but also require the 2 analytic stories or a ProxyShell and CobaltStrike to fire. Adversaries will exploit the vulnerable Exchange server, abuse SSRF, drop a web shell, utilize the PowerShell Exchange modules and begin post-exploitation.
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search: '| 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.analyticstories) as analyticstories 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 dc(All_Risk.analyticstories) as dc_analyticstories from datamodel=Risk.All_Risk where All_Risk.analyticstories IN ("ProxyNotShell","ProxyShell") OR (All_Risk.analyticstories IN ("ProxyNotShell","ProxyShell") AND All_Risk.analyticstories="Cobalt Strike") All_Risk.risk_object_type="system" by _time span=1h All_Risk.risk_object All_Risk.risk_object_type | `drop_dm_object_name(All_Risk)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`| where source_count >=5
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| `proxyshell_proxynotshell_behavior_detected_filter`'
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how_to_implement: To implement this correlation, you will need to enable ProxyShell, ProxyNotShell and Cobalt Strike analytic stories (the anaytics themselves) and ensure proper data is being collected for Web and Endpoint datamodels. Run the correlation rule seperately to validate it is not triggering too much or generating incorrectly. Validate by running ProxyShell POC code and Cobalt Strike behavior.
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known_false_positives: False positives will be limited, however tune or modify the query as needed.
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references:
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- https://www.gteltsc.vn/blog/warning-new-attack-campaign-utilized-a-new-0day-rce-vulnerability-on-microsoft-exchange-server-12715.html
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- https://msrc-blog.microsoft.com/2022/09/29/customer-guidance-for-reported-zero-day-vulnerabilities-in-microsoft-exchange-server/
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tags:
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analytic_story:
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- ProxyShell
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- ProxyNotShell
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asset_type: Web Server
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cis20:
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- CIS 3
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- CIS 5
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- CIS 16
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confidence: 90
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context:
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- Scope:Network
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1190/proxyshell/proxyshell-risk.log
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impact: 90
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kill_chain_phases:
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- Exploitation
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message: ProxyShell or ProxyNotShell activity has been identified on $risk_object$.
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mitre_attack_id:
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- T1190
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nist:
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- DE.CM
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observable:
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- name: risk_object
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type: Hostname
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role:
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- Victim
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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required_fields:
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- All_Risk.analyticstories
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- All_Risk.risk_object_type
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- All_Risk.risk_object
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- All_Risk.annotations.mitre_attack.mitre_tactic
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- source
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risk_score: 81
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security_domain: network
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