2017-07-08 14:37:44 +00:00
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title: Empty User Agent
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2019-11-12 22:12:27 +00:00
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id: 21e44d78-95e7-421b-a464-ffd8395659c4
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2017-07-08 14:37:44 +00:00
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status: experimental
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description: Detects suspicious empty user agent strings in proxy logs
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author: Florian Roth
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2020-01-30 14:20:52 +00:00
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date: 2017/07/08
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2020-09-03 14:16:47 +00:00
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modified: 2020/09/03
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2020-09-15 13:02:30 +00:00
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references:
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- https://twitter.com/Carlos_Perez/status/883455096645931008
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2017-07-08 14:37:44 +00:00
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logsource:
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2017-09-10 22:35:52 +00:00
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category: proxy
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2017-07-08 14:37:44 +00:00
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detection:
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selection:
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2020-01-30 14:20:52 +00:00
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# Empty string - as used by Powershell's (New-Object Net.WebClient).DownloadString
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2019-12-06 23:11:33 +00:00
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c-useragent: ''
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2017-07-08 14:37:44 +00:00
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condition: selection
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2017-09-12 21:54:04 +00:00
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fields:
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- ClientIP
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2019-12-06 23:11:33 +00:00
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- c-uri
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- c-useragent
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2017-07-08 14:37:44 +00:00
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falsepositives:
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- Unknown
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level: medium
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2020-09-15 13:02:30 +00:00
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tags:
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- attack.defense_evasion
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- attack.command_and_control
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- attack.t1071.001
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