Menu
The review-first prompt is selected by default. You can switch to a direct command or download a local copy.
Read SKILL.md and any companion files shown by SkillsMP before deciding whether to install.
Install with Codex or Claude Copy this prompt, paste it into Codex, Claude, or another assistant, and let it review the skill page and install it for you.
A direct command skips the review prompt. Inspect the source before running it.
npx skills add https://github.com/CyberStrikeus/CyberStrike --skill cis-ubuntu1804-v220-1-1-1-3The command stays on one line. Scroll horizontally to inspect it before copying.
Prefer a local copy? Download the files currently available to SkillsMP.
macOS post-exploitation for credential harvesting, DTrace monitoring, TCC bypass, and stealth operations via native tools
Windows userland post-exploitation for credential harvesting, monitoring, AMSI/ETW bypass, and stealth operations
Kubernetes post-exploitation for container escape, secret extraction, RBAC abuse, and cluster persistence
Showing SKILL.md
Based on SOC occupation classification
| name | cis-ubuntu1804-v220-1-1-1-3 |
| description | Ensure mounting of jffs2 filesystems is disabled |
| category | cis-storage |
| version | 2.2.0 |
| author | cyberstrike-official |
| tags | ["cis","ubuntu","linux","ubuntu-18.04","filesystem","jffs2","kernel-module"] |
| cis_id | 1.1.1.3 |
| cis_benchmark | CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 |
| tech_stack | ["ubuntu","linux"] |
| cwe_ids | [] |
| chains_with | [] |
| prerequisites | [] |
| severity_boost | {} |
Level 1 - Server / Level 1 - Workstation, Assessment: Automated
The jffs2 (journaling flash filesystem 2) filesystem type is a log-structured filesystem used in flash memory devices.
Removing support for unneeded filesystem types reduces the local attack surface of the system. If this filesystem type is not needed, disable it.
None noted.
Run the following script to verify the jffs2 module is disabled. If the module is available in the running kernel:
/bin/true or /bin/false exists in a file within the /etc/modprobe.d/ directory/etc/modprobe.d/ directoryIf available in ANY installed kernel:
/etc/modprobe.d/ directory#!/usr/bin/env bash
{
l_output="" l_output2="" l_output3="" l_dl=""
l_mname="jffs2"
l_mtype="fs"
l_searchloc="/lib/modprobe.d/*.conf /usr/local/lib/modprobe.d/*.conf /run/modprobe.d/*.conf /etc/modprobe.d/*.conf"
l_mpath="/lib/modules/**/kernel/$l_mtype"
l_mpname="$(tr '-' ' ' <<< "$l_mname")"
l_mndir="$(tr '-' '/' <<< "$l_mname")"
module_loadable_chk()
{
l_loadable="$(modprobe -n -v "$l_mname")"
[ "$(wc -l <<< "")" -gt ] && l_loadable=
grep -Pq -- <<< ;
l_output=
l_output2=
}
()
{
! lsmod | grep > /dev/null 2>&1;
l_output=
l_output2=
}
()
{
l_dl=
modprobe --showconfig | grep -Pq -- ;
l_output=
l_output2=
}
l_mdir ;
[ -d ] && [ -n ];
l_output3=
[ != ] && module_deny_chk
[ = ];
module_loadable_chk
module_loaded_chk
l_output=
[ -n ] && -e
[ -z ];
-e
-e
[ -n ] && -e
}
If the module is available in the running kernel:
install jffs2 /bin/false in the /etc/modprobe.d/ directoryblacklist jffs2 in the /etc/modprobe.d/ directoryIf available in ANY installed kernel:
blacklist jffs2 in the /etc/modprobe.d/ directoryIf the kernel module is not available on the system or pre-compiled into the kernel:
#!/usr/bin/env bash
{
l_mname="jffs2"
l_mtype="fs"
l_mpath="/lib/modules/**/kernel/$l_mtype"
l_mpname="$(tr '-' ' ' <<< "$l_mname")"
l_mndir="$(tr '-' '/' <<< "$l_mname")"
module_loadable_fix()
{
l_loadable="$(modprobe -n -v "$l_mname")"
[ "$(wc -l <<< "$l_loadable")" -gt "1" ] && l_loadable="$(grep -P -- "(^\h*install|\b$l_mname)\b" <<< "$l_loadable")"
if ! grep -Pq -- '^\h*install \/bin\/(true|false)' <<< "$l_loadable"; then
echo -e "\n - setting module: \"$l_mname\" to be not loadable"
echo -e "install $l_mname /bin/false" >> /etc/modprobe.d/"$l_mpname".conf
fi
}
module_loaded_fix()
{
if lsmod | grep "$l_mname" > /dev/null 2>&1; then
echo -e "\n - unloading module \"$l_mname\""
modprobe -r "$l_mname"
fi
}
module_deny_fix()
{
if ! modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mpname\b"; then
echo -e "\n - deny listing \"$l_mname\""
echo -e "blacklist $l_mname" >> /etc/modprobe.d/"$l_mpname".conf
fi
}
for l_mdir in $l_mpath; do
if [ -d "$l_mdir/$l_mndir" ] && [ -n "$(ls -A $l_mdir/$l_mndir)" ]; then
echo -e "\n - module: \"$l_mname\" exists in \"$l_mdir\"\n - checking if disabled..."
module_deny_fix
if [ "$l_mdir" = "/lib/modules/$(uname -r)/kernel/$l_mtype" ]; then
module_loadable_fix
module_loaded_fix
fi
else
echo -e "\n - module: \"$l_mname\" doesn't exist in \"$l_mdir\"\n"
fi
done
echo -e "\n - remediation of module: \"$l_mname\" complete\n"
}
Not disabled by default.
v8 - 4.8 Uninstall or Disable Unnecessary Services on Enterprise Assets and Software (IG 2, IG 3) v7 - 9.2 Ensure Only Approved Ports, Protocols and Services Are Running (IG 2, IG 3)
MITRE ATT&CK Mappings: T1005, T1005.000 (TA0005) - M1050