MacOS.Sys.SUID

Searches for applications that have the setuid or setgid bits set.

When the setuid or setgid bits are set on Linux or macOS for an application, this means that the application will run with the privileges of the owning user or group respectively. Normally an application is run in the current user’s context, regardless of which user or group owns the application. There are instances where programs need to be executed in an elevated context to function properly, but the user running them doesn’t need the elevated privileges. Instead of creating an entry in the sudoers file, which must be done by root, any user can specify the setuid or setgid flag to be set for their own applications. These bits are indicated with an “s” instead of an “x” when viewing a file’s attributes via ls -l. The chmod program can set these bits with via bitmasking, chmod 4777 [file] or via shorthand naming, chmod u+s [file].

An adversary can take advantage of this to either do a shell escape or exploit a vulnerability in an application with the setsuid or setgid bits to get code running in a different user’s context. Additionally, adversaries can use this mechanism on their own malware to ensure that they’re able to execute in elevated contexts in the future.

name: Linux.Sys.SUID
aliases:
  - MacOS.Sys.SUID
description: |
  Searches for applications that have the `setuid` or `setgid` bits set.

  When the `setuid` or `setgid` bits are set on Linux or macOS for an
  application, this means that the application will run with the
  privileges of the owning user or group respectively. Normally an
  application is run in the current user’s context, regardless of
  which user or group owns the application. There are instances where
  programs need to be executed in an elevated context to function
  properly, but the user running them doesn’t need the elevated
  privileges. Instead of creating an entry in the `sudoers` file, which
  must be done by root, any user can specify the `setuid` or `setgid` flag
  to be set for their own applications. These bits are indicated with
  an "s" instead of an "x" when viewing a file's attributes via `ls
  -l`. The `chmod` program can set these bits with via bitmasking, `chmod
  4777 [file]` or via shorthand naming, `chmod u+s [file]`.

  An adversary can take advantage of this to either do a shell escape
  or exploit a vulnerability in an application with the setsuid or
  setgid bits to get code running in a different user's
  context. Additionally, adversaries can use this mechanism on their
  own malware to ensure that they're able to execute in elevated
  contexts in the future.

reference:
  - https://attack.mitre.org/techniques/T1166/

parameters:
  - name: GlobExpression
    default: /usr/**

sources:
  - query: |
      SELECT Mode.String AS Mode,
               OSPath, Size,
               Mtime,
               Sys.Uid AS OwnerID,
               Sys.Gid AS GroupID
      FROM glob(globs=GlobExpression) WHERE Mode =~ '^g|u'