6.1.14 Audit SGID executables (Not Scored)

Level 1 - Server
Level 1 - Workstation 

The owner of a file can set the file's permissions to run with the owner's or group's permissions, even if the user running the program is not the owner or a member of the group. The most common reason for a SGID program is to enable users to perform functions (such as changing their password) that require root privileges.

There are valid reasons for SGID programs, but it is important to identify and review such programs to ensure they are legitimate. Review the files returned by the action in the audit section and check to see if system binaries have a different md5 checksum than what from the package. This is an indication that the binary may have been replaced.

Run the following command to list SGID files:

# df --local -P | awk {'if (NR!=1) print $6'} | xargs -I '{}' find '{}' -xdev -type f -perm -2000

The command above only searches local filesystems, there may still be compromised items on network mounted partitions. Additionally the –local option to df is not universal to all versions, it can be omitted to search all filesystems on a system including network mounted filesystems or the following command can be run manually for each partition:

# find <partition> -xdev -type f -perm -2000

Ensure that no rogue SGID programs have been introduced into the system. Review the files returned by the action in the Audit section and confirm the integrity of these binaries.

  • ubuntu1604/6/1/14.txt
  • Last modified: 2017/05/04 14:12
  • by Piotr Kłoczewski