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6.3.3.7 Ensure unsuccessful file access attempts are collected

Warning! Audit Deprecated

This audit has been deprecated and will be removed in a future update.

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Information

Monitor for unsuccessful attempts to access files. The following parameters are associated with system calls that control files:

 - creation - creat
 - opening - open, openat
 - truncation - truncate, ftruncate

An audit log record will only be written if all of the following criteria is met for the user when trying to access a file:

 - a non-privileged user (auid>=UID_MIN)
 - is not a Daemon event (auid=4294967295/unset/-1)
 - if the system call returned EACCES (permission denied) or EPERM (some other permanent error associated with the specific system call)

Failed attempts to open, create or truncate files could be an indication that an individual or process is trying to gain unauthorized access to the system.

Solution

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 unsuccessful file access attempts.

Example:

# {
UID_MIN=$(awk '/^\s*UID_MIN/{print $2}' /etc/login.defs)
[ -n "${UID_MIN}" ] && printf "
-a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-EACCES -F auid>=${UID_MIN} -F auid!=unset -k access
-a always,exit -F arch=b64 -S creat,open,openat,truncate,ftruncate -F exit=-EPERM -F auid>=${UID_MIN} -F auid!=unset -k access
-a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-EACCES -F auid>=${UID_MIN} -F auid!=unset -k access
-a always,exit -F arch=b32 -S creat,open,openat,truncate,ftruncate -F exit=-EPERM -F auid>=${UID_MIN} -F auid!=unset -k access
" >> /etc/audit/rules.d/50-access.rules || printf "ERROR: Variable 'UID_MIN' is unset.\n"
}

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

See Also

https://workbench.cisecurity.org/benchmarks/18208

Item Details

References: CSCv7|14.9

Plugin: Unix

Control ID: 94b65dfee3965848ab247804cf6825c8bf4bee8565f5f9a79808dc960e5fda28