D4rkCiph3r
35 lines
1.3 KiB
YAML
35 lines
1.3 KiB
YAML
title: Binary Padding - MacOS
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id: 95361ce5-c891-4b0a-87ca-e24607884a96
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status: test
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description: Adversaries may use binary padding to add junk data and change the on-disk representation of malware. This rule detect using dd and truncate to add a junk data to file.
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references:
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- https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1027.001/T1027.001.md
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author: 'Igor Fits, Mikhail Larin, oscd.community'
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date: 2020/10/19
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modified: 2022/11/26
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tags:
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- attack.defense_evasion
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- attack.t1027.001
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logsource:
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product: macos
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category: process_creation
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detection:
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selection1:
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Image|endswith: '/truncate'
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CommandLine|contains: '-s +'
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filter1:
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CommandLine|contains:
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- '-s 0' #truncates to zero, no padding
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- '-s -' #file size will be reduced, no padding
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selection2:
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Image|endswith: '/dd'
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CommandLine|contains:
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- 'if=/dev/zero' #if input is not /dev/zero, then there is no null padding
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- 'if=/dev/random' #high-quality random data
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- 'if=/dev/urandom' #low-quality random data
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#Discarding the filter, there should either be "of="(output file) or a redirection or append symbol
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condition: (selection1 and not filter1) or (selection2)
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falsepositives:
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- Legitimate script work
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level: high
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