cis-ubuntu2004-v300-6-3-3-2

DevOps & Security

Ensure actions as another user are always logged

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6.3.3.2 Ensure actions as another user are always logged (Automated)

Profile

Level 2 - Server
Level 2 - Workstation

Description

sudo provides users with temporary elevated privileges to perform operations, either as the superuser or another user.

Rationale

Creating an audit log of users with temporary elevated privileges and the operation(s) they performed is essential to reporting. Administrators will want to correlate the events written to the audit trail with the records written to sudo's logfile to verify if unauthorized commands have been executed.

Audit Procedure

Command Line

On disk configuration - Run the following command to check the on disk rules:

# awk '/^ *-a *always,exit/ \
&&/ -F *arch=b(32|64)/ \
&&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
&&(/ -C *euid!=uid/||/ -C *uid!=euid/) \
&&/ -S *execve/ \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)' /etc/audit/rules.d/*.rules

Verify the output matches:

-a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k user_emulation
-a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S execve -k user_emulation

Running configuration - Run the following command to check loaded rules:

# auditctl -l | awk '/^ *-a *always,exit/ \
&&/ -F *arch=b(32|64)/ \
&&(/ -F *auid!=unset/||/ -F *auid!=-1/||/ -F *auid!=4294967295/) \
&&(/ -C *euid!=uid/||/ -C *uid!=euid/) \
&&/ -S *execve/ \
&&(/ key= *[!-~]* *$/||/ -k *[!-~]* *$/)'

Verify the output matches:

-a always,exit -F arch=b64 -S execve -C uid!=euid -F auid!=-1 -F key=user_emulation
-a always,exit -F arch=b32 -S execve -C uid!=euid -F auid!=-1 -F key=user_emulation

Expected Result

Both on disk and running configuration should show execve rules tracking user emulation.

Remediation

Command Line

Create audit rules - Edit or create a file in the /etc/audit/rules.d/ directory, ending in .rules extension, with the relevant rules to monitor elevated privileges.

Example:

# printf "
-a always,exit -F arch=b64 -C euid!=uid -F auid!=unset -S execve -k user_emulation
-a always,exit -F arch=b32 -C euid!=uid -F auid!=unset -S execve -k user_emulation
" >> /etc/audit/rules.d/50-user_emulation.rules

Load audit rules - Merge and load the rules into active configuration:

# augenrules --load

Check if reboot is required:

# if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot required to load rules\n"; fi

References

NIST SP 800-53 Rev. 5: AU-3

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	8.5 Collect Detailed Audit Logs		X	X
v7	4.9 Log and Alert on Unsuccessful Administrative Account Login		X	X

MITRE ATT&CK Mappings: T1562, T1562.006 / TA0004 / M1047