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Potential Command and Control via Internet Explorer

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Potential Command and Control via Internet Explorer

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Identifies instances of Internet Explorer (iexplore.exe) being started via the Component Object Model (COM) making unusual network connections. Adversaries could abuse Internet Explorer via COM to avoid suspicious processes making network connections and bypass host-based firewall restrictions.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

Tags:

Elastic
Host
Windows
Threat Detection
Command and Control

Version: 4 (version history)

Added (Elastic Stack release): 7.11.0

Last modified (Elastic Stack release): 7.16.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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Processes such as MS Office using IEproxy to render HTML content.

Rule query

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sequence by host.id, user.id with maxspan = 5s [library where
dll.name : "IEProxy.dll" and process.name : ("rundll32.exe",
"regsvr32.exe")] [process where event.type == "start" and
process.parent.name : "iexplore.exe" and process.parent.args :
"-Embedding"] /* IE started via COM in normal conditions makes few
connections, mainly to Microsoft and OCSP related domains, add FPs
here */ [network where network.protocol == "dns" and process.name :
"iexplore.exe" and not dns.question.name : (
"*.microsoft.com", "*.digicert.com", "*.msocsp.com",
"*.windowsupdate.com", "*.bing.com", "*.identrust.com",
"*.sharepoint.com", "*.office365.com", "*.office.com" )
]

Threat mapping

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Framework: MITRE ATT&CK^TM

Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
Technique:
- Name: Application Layer Protocol
- ID: T1071
- Reference URL: https://attack.mitre.org/techniques/T1071/
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
Technique:
- Name: Inter-Process Communication
- ID: T1559
- Reference URL: https://attack.mitre.org/techniques/T1559/

Rule version history

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Version 4 (7.16.0 release)

Formatting only

Version 3 (7.13.0 release)

Updated query, changed from:

sequence by host.id, process.entity_id with maxspan = 1s [process
where event.type == "start" and process.parent.name : "iexplore.exe"
and process.parent.args : "-Embedding"] /* IE started via COM in
normal conditions makes few connections, mainly to Microsoft and OCSP
related domains, add FPs here */ [network where network.protocol ==
"dns" and process.name : "iexplore.exe" and not dns.question.name :
( "*.microsoft.com", "*.digicert.com", "*.msocsp.com",
"*.windowsupdate.com", "*.bing.com", "*.identrust.com" )
]

Version 2 (7.12.0 release)

Updated query, changed from:

sequence by host.id, process.entity_id with maxspan = 1s [process
where event.type:"start" and process.parent.name:"iexplore.exe" and
process.parent.args:"-Embedding"] /* IE started via COM in normal
conditions makes few connections, mainly to Microsoft and OCSP related
domains, add FPs here */ [network where network.protocol : "dns" and
process.name:"iexplore.exe" and not wildcard(dns.question.name,
"*.microsoft.com",
"*.digicert.com", "*.msocsp.com",
"*.windowsupdate.com",
"*.bing.com", "*.identrust.com")
]

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