cis-ubuntu2004-v300-6-1-3

DevOps & Security

Ensure cryptographic mechanisms are used to protect the integrity of audit tools

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_20.04_LTS_Benchmark_v3.0.0/cis-ubuntu2004-v300-6-1-3/SKILL.md

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6.1.3 Ensure cryptographic mechanisms are used to protect the integrity of audit tools (Automated)

Profile

Level 1 - Server
Level 1 - Workstation

Description

Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.

Rationale

Protecting the integrity of the tools used for auditing purposes is a critical step toward ensuring the integrity of audit information. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity.

Attackers may replace the audit tools or inject code into the existing tools with the purpose of providing the capability to hide or erase system activity from the audit logs.

Audit tools should be cryptographically signed in order to provide the capability to identify when the audit tools have been modified, manipulated, or replaced. An example is a checksum hash of the file or files.

Audit Procedure

Command Line

Verify that Advanced Intrusion Detection Environment (AIDE) is properly configured. Run the following command to verify that AIDE is configured to use cryptographic mechanisms to protect the integrity of audit tools:

# grep -Ps -- '(\/sbin\/(audit|au)\H*\b)' /etc/aide.conf /etc/aide/aide.conf /etc/aide.conf.d/*.conf /etc/aide/aide.conf.d/*

Expected Result

Verify the output includes:

/sbin/auditctl p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/auditd p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/ausearch p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/aureport p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/autrace p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/augenrules p+i+n+u+g+s+b+acl+xattrs+sha512

Remediation

Command Line

Add or update the following selection lines for to a file ending in .conf in the /etc/aide/aide.conf.d/ or to /etc/aide/aide.conf to protect the integrity of the audit tools:

# Audit Tools
/sbin/auditctl p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/auditd p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/ausearch p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/aureport p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/autrace p+i+n+u+g+s+b+acl+xattrs+sha512
/sbin/augenrules p+i+n+u+g+s+b+acl+xattrs+sha512

Default Value

Not configured by default.

References

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

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	—
v7	—

MITRE ATT&CK Mappings

Techniques / Sub-techniques	Tactics	Mitigations
T1070, T1070.002, T1083, T1083.000	TA0007	M1047