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43 lines
1.6 KiB
YAML
43 lines
1.6 KiB
YAML
title: Suspicious User Agent
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id: 7195a772-4b3f-43a4-a210-6a003d65caa1
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status: experimental
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description: Detects suspicious malformed user agent strings in proxy logs
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author: Florian Roth
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date: 2017/07/08
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modified: 2020/09/03
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references:
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- https://github.com/fastly/waf_testbed/blob/master/templates/default/scanners-user-agents.data.erb
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logsource:
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category: proxy
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detection:
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selection:
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c-useragent:
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# Badly scripted UA
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- 'user-agent' # User-Agent: User-Agent:
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- '* (compatible;MSIE *' # typical typo - missing space
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- '*.0;Windows NT *' # typical typo - missing space
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- 'Mozilla/3.0 *'
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- 'Mozilla/2.0 *'
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- 'Mozilla/1.0 *'
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- 'Mozilla *' # missing slash
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- ' Mozilla/*' # leading space
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- 'Mozila/*' # single 'l'
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- '_'
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- 'CertUtil URL Agent' # https://twitter.com/stvemillertime/status/985150675527974912
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- 'Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:60.0)' # CobaltStrike Beacon https://unit42.paloaltonetworks.com/tracking-oceanlotus-new-downloader-kerrdown/
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- 'Mozilla/5.0 (Windows NT 6.3; WOW64; rv:28.0) Gecko/20100101 Firefox/28.0' # used by APT28 malware https://threatvector.cylance.com/en_us/home/inside-the-apt28-dll-backdoor-blitz.html
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- 'HTTPS' # https://twitter.com/stvemillertime/status/1204437531632250880
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falsepositives:
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c-useragent:
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- 'Mozilla/3.0 * Acrobat *' # Acrobat with linked content
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condition: selection and not falsepositives
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fields:
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- ClientIP
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- c-uri
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- c-useragent
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falsepositives:
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- Unknown
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level: high
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tags:
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- attack.command_and_control
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- attack.t1071.001 |