osquery-defense-kit/detection/evasion/unexpected-tmp-executables-macos.sql

-- Find unexpected executables in temp directories, often used by malware droppers
--
-- false positives:
--   * developers building code out of /tmp
--
-- tags: persistent seldom
-- platform: darwin
SELECT DISTINCT
  file.path,
  uid,
  gid,
  mode,
  REGEX_MATCH (RTRIM(file.path, '/'), '.*\.(.*?)$', 1) AS extension,
  file.btime,
  file.ctime,
  file.mtime,
  file.type,
  file.size,
  hash.sha256,
  magic.data,
  signature.identifier,
  signature.authority
FROM
  file
  LEFT JOIN hash on file.path = hash.path
  LEFT JOIN magic ON file.path = magic.path
  LEFT JOIN signature ON file.path = signature.path
WHERE -- Optimization: don't join things until we have a whittled down list of files
  file.path IN (
    SELECT
      path
    FROM
      file
    WHERE
      (
        file.directory = '/tmp'
        OR file.directory LIKE '/tmp/%'
        OR file.directory LIKE '/tmp/%/%'
        OR file.directory LIKE '/tmp/%/.%'
        OR file.directory LIKE '/tmp/.%'
        OR file.directory LIKE '/tmp/.%/%'
        or file.directory LIKE '/tmp/.%/.%'
      ) -- Prevent weird recursion
      AND NOT file.directory LIKE '%/../%'
      AND NOT file.directory LIKE '%/./%' -- Exclude very temporary files
      AND NOT (strftime('%s', 'now') - ctime) < 60 -- Only executable files
      AND file.type = 'regular'
      AND (
        file.mode LIKE '%7%'
        or file.mode LIKE '%5%'
        or file.mode LIKE '%1%'
      )
      AND NOT (
        uid > 500
        AND (
          file.path LIKE '%/go-build%'
          OR file.path LIKE '%/bin/%'
          OR file.path LIKE '%/sbin/%'
          OR file.path LIKE '/tmp/%ctl'
          OR file.path LIKE '%/CCLBS/%'
          OR file.path LIKE '%/checkout/%'
          OR file.path LIKE '%/ci/%'
          OR file.path LIKE '%/debug/%'
          OR file.path LIKE '%/dist/%'
          OR file.path LIKE '%/etc/network/if-up.d/%'
          OR file.path LIKE '%/flow/%.npmzS_cacachezStmpzSgit-clone%'
          OR file.path LIKE '/tmp/GoLand/___Test%.test'
          OR file.path LIKE '%/git/%'
          OR file.path LIKE '%/github/%'
          OR file.path LIKE '%/go.%.sum'
          OR file.path LIKE "%/%/gradlew"
          OR file.path LIKE '%/guile-%/guile-%'
          OR file.path LIKE '%/ko/%'
          OR file.path LIKE '%/nix/%'
          OR file.path LIKE '%/kots/%'
          OR file.path LIKE '/tmp/%/AdobePIM.dylib'
          OR file.path LIKE "%/lib/%.so"
          OR file.path LIKE '/tmp/melange%'
          OR file.path LIKE "%/lib/%.so.%"
          OR file.path LIKE '%/pdf-tools/%'
          OR file.path LIKE '%/Photoshop Installer.app/Contents/%'
          OR file.path LIKE '%-release%/%'
          OR file.path LIKE '%/site-packages/markupsafe/_speedups.cpython-%'
          OR file.path LIKE '%/src/%'
          OR file.path LIKE '%/target/%'
          OR file.path LIKE '%/terraformer/%'
          OR file.path LIKE '/tmp/com.apple.installer%'
          OR file.path LIKE '%/tmp/epdf%'
          OR file.path LIKE '/tmp/flow/%.npmzS_cacachezStmpzSgit-clone%'
          OR file.filename IN ('mysqld_exporter', 'goreleaser')
        )
      )
      -- Melange
      AND NOT file.directory LIKE '/tmp/melange-guest-%'
      -- Nix
      AND NOT (
        file.directory LIKE '/tmp/tmp%'
        AND gid = 0
        AND uid > 300
        AND uid < 350
      ) -- Babel
      AND NOT (
        file.directory LIKE '/tmp/babel-%/sh-script-%'
        AND gid > 900
        AND uid = 1000
        AND size < 1024
      ) -- Random Testdata
      AND NOT (
        gid > 900
        AND uid = 1000
        AND (
          file.directory LIKE '/tmp/%/test'
          OR file.directory LIKE '/tmp/%/testdata'
        )
      ) -- macOS updates
      AND NOT file.directory LIKE '/tmp/msu-target-%' -- I don't know man. I don't work here.
      AND NOT file.directory LIKE '/tmp/UpdateBrain-%/AssetData/com.apple.MobileSoftwareUpdate.UpdateBrainService.xpc/Contents/MacOS' -- terraform
      AND NOT file.directory LIKE '/tmp/staged-updates%'
      AND NOT (
        uid > 500
        AND file.path LIKE '/tmp/terraform_%/terraform'
      )
      AND NOT (
        file.path LIKE '/tmp/%compressed'
        AND size < 4000
        AND uid > 500
      ) -- Executables too small to even hold '#!/bin/sh\nuid'
      AND NOT (
        file.type = 'regular'
        AND size < 10
      ) -- TODO: Remove this hardcoded entry after Apr 2023
      AND NOT (
        file.path = '/tmp/policy-tester'
        AND file.uid = 501
        AND file.gid = 20
        AND file.size = 90921938
      )
  )
  AND NOT (
    magic.data IS NOT NULL
    AND (
      magic.data IN ('JSON data', 'ASCII text')
      OR magic.data LIKE 'ELF %-bit %SB executable%'
      OR magic.data LIKE 'symbolic link to %'
      OR magic.data LIKE 'ELF %-bit LSB shared object%'
      OR magic.data LIKE 'libtool library file,%'
      OR (
        file.filename IN ("configure", "mkinstalldirs", "config.status")
        AND magic.data LIKE "POSIX shell script, ASCII text executable%"
      )
      OR (
        file.size < 50000
        AND file.uid > 500
        AND extension IN (
          'adoc',
          'md',
          'bat',
          'java',
          'js',
          'json',
          'log',
          'nib',
          'pem',
          'perl',
          'pl',
          'py',
          'script',
          'sh',
          'status',
          'strings',
          'txt',
          'yaml',
          'yml'
        )
        AND magic.data NOT LIKE "%Mach-O%"
      )
    )
  )