151 lines
9.2 KiB
Markdown
151 lines
9.2 KiB
Markdown
# 2049 - Pentesting NFS Service
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<details>
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<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
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* **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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## **Basic Information**
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It is a client/server system that allows users to access files across a network and treat them as if they resided in a local file directory. It has the same purpose as SMB but it cannot talk to SMB.
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The NFS protocol has **no mechanism for authentication** or **authorization**. The authorization is taken from the available information of the file system where the server is responsible for translating the **user information** supplied by the **client** to that of the **file system** and converting the corresponding authorization information as correctly as possible into the syntax required by UNIX.
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The most common **authentication is via UNIX `UID`/`GID` and `group memberships`**, which is why this syntax is most likely to be applied to the NFS protocol. One problem is that the **client** and **server** do **not necessarily** have to have the **same mappings of UID/GID** to users and groups. No further checks can be made on the part of the server. This is why NFS should **only** be used with this authentication method in **trusted networks**.
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**Default port**: 2049/TCP/UDP (except version 4, it just needs TCP or UDP). 
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```
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2049/tcp open nfs 2-3 (RPC #100003
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```
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### Versions
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(From [https://academy.hackthebox.com/module/112/section/1068](https://academy.hackthebox.com/module/112/section/1068))
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| **Version** | **Features** |
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| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `NFSv2` | It is **older** but is supported by many systems and was initially operated entirely over UDP. |
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| `NFSv3` | It has more features, including variable file size and better error reporting, but is not fully compatible with NFSv2 clients. |
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| `NFSv4` | It includes Kerberos, works through firewalls and on the Internet, **no longer requires portmappers**, supports ACLs, applies state-based operations, and provides performance improvements and high **security**. It is also the first version to have a stateful protocol. |
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## Enumeration
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### Useful nmap scripts
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```bash
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nfs-ls #List NFS exports and check permissions
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nfs-showmount #Like showmount -e
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nfs-statfs #Disk statistics and info from NFS share
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```
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### Useful metasploit modules
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```bash
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scanner/nfs/nfsmount #Scan NFS mounts and list permissions
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```
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### Mounting
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To know **which folder** has the server **available** to mount you an ask it using:
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```bash
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showmount -e <IP>
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```
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Then mount it using:
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```bash
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mount -t nfs [-o vers=2] <ip>:<remote_folder> <local_folder> -o nolock
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```
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You should specify to **use version 2** because it doesn't have **any** **authentication** or **authorization**.
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**Example:**
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```bash
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mkdir /mnt/new_back
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mount -t nfs [-o vers=2] 10.12.0.150:/backup /mnt/new_back -o nolock
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```
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## Permissions
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If you mount a folder which contains **files or folders only accesible by some user** (by **UID**). You can **create** **locally** a user with that **UID** and using that **user** you will be able to **access** the file/folder.
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## NSFShell
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To easily list, mount and change UID and GID to have access to files you can use [nfsshell](https://github.com/NetDirect/nfsshell).
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[Nice NFSShell tutorial.](https://www.pentestpartners.com/security-blog/using-nfsshell-to-compromise-older-environments/)
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## Config files
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```
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/etc/exports
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/etc/lib/nfs/etab
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```
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### Dangerous settings
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(From [https://academy.hackthebox.com/module/112/section/1068](https://academy.hackthebox.com/module/112/section/1068))
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| **Option** | **Description** |
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| ---------------- | -------------------------------------------------------------------------------------------------------------------- |
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| `rw` | Read and write permissions. |
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| `insecure` | Ports above 1024 will be used. |
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| `nohide` | If another file system was mounted below an exported directory, this directory is exported by its own exports entry. |
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| `no_root_squash` | All files created by root are kept with the UID/GID 0. |
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| `no_all_squash` | |
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## Privilege Escalation using NFS misconfigurations
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[NFS no\_root\_squash and no\_all\_squash privilege escalation](../linux-hardening/privilege-escalation/nfs-no\_root\_squash-misconfiguration-pe.md)
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## HackTricks Automatic Commands
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```
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Protocol_Name: NFS #Protocol Abbreviation if there is one.
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Port_Number: 2049 #Comma separated if there is more than one.
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Protocol_Description: Network File System #Protocol Abbreviation Spelled out
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Entry_1:
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Name: Notes
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Description: Notes for NFS
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Note: |
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It is a client/server system that allows users to access files across a network and treat them as if they resided in a local file directory.
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#apt install nfs-common
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showmount 10.10.10.180 ~or~showmount -e 10.10.10.180
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should show you available shares (example /home)
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mount -t nfs -o ver=2 10.10.10.180:/home /mnt/
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cd /mnt
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nano into /etc/passwd and change the uid (probably 1000 or 1001) to match the owner of the files if you are not able to get in
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https://book.hacktricks.xyz/pentesting/nfs-service-pentesting
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Entry_2:
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Name: Nmap
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Description: Nmap with NFS Scripts
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Command: nmap --script=nfs-ls.nse,nfs-showmount.nse,nfs-statfs.nse -p 2049 {IP}
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```
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<details>
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<summary><strong>HackTricks in </strong><a href="https://twitter.com/carlospolopm"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>
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* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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* **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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