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fix(rules/Set Setuid or Setgid bit): use chmod syscalls instead of chmod command #765

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merged 2 commits into from
Aug 16, 2019
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fix(rules/Set Setuid or Setgid bit): use chmod syscalls instead of chmod command #765

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ac44627
fix(rules/Set Setuid or Setgid bit): use chmod syscalls instead of ch…
fntlnz Aug 13, 2019
d586ec5
fix(rules): make chmod rules enabled by default
fntlnz Aug 14, 2019
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14 changes: 10 additions & 4 deletions rules/falco_rules.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -72,6 +72,9 @@
- macro: create_symlink
condition: evt.type in (symlink, symlinkat) and evt.dir=<

- macro: chmod
condition: (evt.type in (chmod, fchmod, fchmodat) and evt.dir=<)

# File categories
- macro: bin_dir
condition: fd.directory in (/bin, /sbin, /usr/bin, /usr/sbin)
Expand Down Expand Up @@ -2409,17 +2412,20 @@
tag: [process, mitre_defense_evation]

- macro: consider_all_chmods
condition: (never_true)
condition: (always_true)

- list: user_known_chmod_applications
items: []

- rule: Set Setuid or Setgid bit
desc: >
When the setuid or setgid bits are set for an application,
this means that the application will run with the privileges of the owning user or group respectively.
Detect setuid or setgid bits set via chmod
condition: consider_all_chmods and spawned_process and proc.name = "chmod" and (proc.args contains "+s" or proc.args contains "4777")
condition: consider_all_chmods and chmod and (evt.arg.mode contains "S_ISUID" or evt.arg.mode contains "S_ISGID") and not proc.cmdline in (user_known_chmod_applications)
output: >
Setuid or setgid bit is set via chmod (user=%user.name command=%proc.cmdline
container_id=%container.id container_name=%container.name image=%container.image.repository:%container.image.tag)
Setuid or setgid bit is set via chmod (fd=%evt.arg.fd filename=%evt.arg.filename mode=%evt.arg.mode user=%user.name
command=%proc.cmdline container_id=%container.id container_name=%container.name image=%container.image.repository:%container.image.tag)
priority:
NOTICE
tag: [process, mitre_persistence]
Expand Down