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P4T12ICK
79 lines
2.9 KiB
YAML
79 lines
2.9 KiB
YAML
name: W3WP Spawning Shell
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id: 0f03423c-7c6a-11eb-bc47-acde48001122
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version: 2
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date: '2021-03-03'
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author: Michael Haag, Splunk
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status: production
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type: TTP
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description: This query identifies a shell, PowerShell.exe or Cmd.exe, spawning from
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W3WP.exe, or IIS. In addition to IIS logs, this behavior with an EDR product will
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capture potential webshell activity, similar to the HAFNIUM Group abusing CVEs,
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on publicly available Exchange mail servers. During triage, review the parent process
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and child process of the shell being spawned. Review the command-line arguments
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and any file modifications that may occur. Identify additional parallel process,
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child processes, that may highlight further commands executed. After triaging, work
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to contain the threat and patch the system that is vulnerable.
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data_source:
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- Sysmon Event ID 1
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search:
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selection1:
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ParentImage: w3wp.exe
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selection2:
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OriginalFileName: Cmd.Exe
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selection3:
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Image|endswith: cmd.exe
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selection4:
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OriginalFileName: Cmd.Exe
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selection5:
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Image|endswith: cmd.exe
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condition: selection1 and selection2 and selection3 or selection4 or selection5
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
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confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
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endpoint product.
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known_false_positives: Baseline your environment before production. It is possible
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build systems using IIS will spawn cmd.exe to perform a software build. Filter as
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needed.
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references:
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- https://www.microsoft.com/security/blog/2020/02/04/ghost-in-the-shell-investigating-web-shell-attacks/
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- https://www.zerodayinitiative.com/blog/2021/8/17/from-pwn2own-2021-a-new-attack-surface-on-microsoft-exchange-proxyshell
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- https://www.youtube.com/watch?v=FC6iHw258RI
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- https://www.huntress.com/blog/rapid-response-microsoft-exchange-servers-still-vulnerable-to-proxyshell-exploit#what-should-you-do
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tags:
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analytic_story:
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- Hermetic Wiper
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- HAFNIUM Group
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- ProxyShell
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- CISA AA22-257A
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- ProxyNotShell
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- CISA AA22-264A
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asset_type: Endpoint
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confidence: 80
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cve:
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- CVE-2021-34473
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- CVE-2021-34523
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- CVE-2021-31207
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impact: 70
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message: Possible Web Shell execution on $dest$
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mitre_attack_id:
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- T1505
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- T1505.003
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observable:
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- name: dest
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type: Endpoint
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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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risk_score: 56
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1505.003/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: xmlwineventlog
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