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RSM logo

Redis Security Map - hide redis server command to attackers

What's RSM

RSM is a proposal specification for Redis SDK clients that allows to hide real Redis command with alias. These alias are mapped in a RSM specification file and only users / application with the map can execute command in the Redis Server

Why

Any user / application with access to the Redis Server can execute any commands. Redis allows to disable some commands and restrict some commands for specific users (this feature was added in Redis 6).

This approach it's oks, but you can improve even more the hardening of your server by using RSM. Then: Only these users with the RSM map can execute commands into Redis Server. Redis server must start with this RSM map (rsm mappers allows you that).

Hacking tools & RSM

RSM is a very good approach to invalidate the Redis hacking tools. To demonstrate them we'll use:

Launching Redis with RSM

You can follow Docker section to launch a Redis instance with RSM.

Our Redis server now runs in 127.0.0.1 at port 6379.

Using nmap

We launch nmap with 2 NSE script trying to discover all our Redis server information:

> nmap -Pn -n 127.0.0.1 -p 6379 -A -sC --script "redis-info,redis-brute" -oN redis-rsm-nmap.txt 
Starting Nmap 7.80 ( https://nmap.org ) at 2020-08-07 11:06 CEST
Nmap scan report for 127.0.0.1
Host is up (0.00025s latency).

PORT     STATE SERVICE VERSION
6379/tcp open  redis?
| fingerprint-strings:
|   FourOhFourRequest:
|     -ERR unknown command `GET`, with args beginning with: `/nice%20ports%2C/Tri%6Eity.txt%2ebak`, `HTTP/1.0`,
|   GetRequest:
|     -ERR unknown command `GET`, with args beginning with: `/`, `HTTP/1.0`,
|   HTTPOptions:
|     -ERR unknown command `OPTIONS`, with args beginning with: `/`, `HTTP/1.0`,
|   Help:
|     -ERR unknown command `HELP`, with args beginning with:
|   LPDString:
|     -ERR unknown command `
|     default`, with args beginning with:
|   RTSPRequest:
|     -ERR unknown command `OPTIONS`, with args beginning with: `/`, `RTSP/1.0`,
|   SIPOptions:
|     -ERR unknown command `OPTIONS`, with args beginning with: `sip:nm`, `SIP/2.0`,
|     -ERR unknown command `Via:`, with args beginning with: `SIP/2.0/TCP`, `nm;branch=foo`,
|     -ERR unknown command `From:`, with args beginning with: `<sip:nm@nm>;tag=root`,
|     -ERR unknown command `To:`, with args beginning with: `<sip:nm2@nm2>`,
|     -ERR unknown command `Call-ID:`, with args beginning with: `50000`,
|     -ERR unknown command `CSeq:`, with args beginning with: `42`, `OPTIONS`,
|     -ERR unknown command `Max-Forwards:`, with args beginning with: `70`,
|     -ERR unknown command `Content-Length:`, with args beginning with: `0`,
|     -ERR unknown command `Contact:`, with args beginning with: `<sip:nm@nm>`,
|     -ERR unknown command `Accept:`, with args beginning with: `application/sdp`,
|   redis-server:
|_    -ERR unknown command `info`, with args beginning with:
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port6379-TCP:V=7.80%I=7%D=8/7%Time=5F2D1988%P=x86_64-apple-darwin19.0.0
SF:%r(redis-server,39,"-ERR\x20unknown\x20command\x20`info`,\x20with\x20ar
SF:gs\x20beginning\x20with:\x20\r\n")%r(GetRequest,49,"-ERR\x20unknown\x20
SF:command\x20`GET`,\x20with\x20args\x20beginning\x20with:\x20`/`,\x20`HTT
SF:P/1\.0`,\x20\r\n")%r(HTTPOptions,4D,"-ERR\x20unknown\x20command\x20`OPT
SF:IONS`,\x20with\x20args\x20beginning\x20with:\x20`/`,\x20`HTTP/1\.0`,\x2
SF:0\r\n")%r(RTSPRequest,4D,"-ERR\x20unknown\x20command\x20`OPTIONS`,\x20w
SF:ith\x20args\x20beginning\x20with:\x20`/`,\x20`RTSP/1\.0`,\x20\r\n")%r(H
SF:elp,39,"-ERR\x20unknown\x20command\x20`HELP`,\x20with\x20args\x20beginn
SF:ing\x20with:\x20\r\n")%r(FourOhFourRequest,6C,"-ERR\x20unknown\x20comma
SF:nd\x20`GET`,\x20with\x20args\x20beginning\x20with:\x20`/nice%20ports%2C
SF:/Tri%6Eity\.txt%2ebak`,\x20`HTTP/1\.0`,\x20\r\n")%r(LPDString,3D,"-ERR\
SF:x20unknown\x20command\x20`\x01default`,\x20with\x20args\x20beginning\x2
SF:0with:\x20\r\n")%r(SIPOptions,302,"-ERR\x20unknown\x20command\x20`OPTIO
SF:NS`,\x20with\x20args\x20beginning\x20with:\x20`sip:nm`,\x20`SIP/2\.0`,\
SF:x20\r\n-ERR\x20unknown\x20command\x20`Via:`,\x20with\x20args\x20beginni
SF:ng\x20with:\x20`SIP/2\.0/TCP`,\x20`nm;branch=foo`,\x20\r\n-ERR\x20unkno
SF:wn\x20command\x20`From:`,\x20with\x20args\x20beginning\x20with:\x20`<si
SF:p:nm@nm>;tag=root`,\x20\r\n-ERR\x20unknown\x20command\x20`To:`,\x20with
SF:\x20args\x20beginning\x20with:\x20`<sip:nm2@nm2>`,\x20\r\n-ERR\x20unkno
SF:wn\x20command\x20`Call-ID:`,\x20with\x20args\x20beginning\x20with:\x20`
SF:50000`,\x20\r\n-ERR\x20unknown\x20command\x20`CSeq:`,\x20with\x20args\x
SF:20beginning\x20with:\x20`42`,\x20`OPTIONS`,\x20\r\n-ERR\x20unknown\x20c
SF:ommand\x20`Max-Forwards:`,\x20with\x20args\x20beginning\x20with:\x20`70
SF:`,\x20\r\n-ERR\x20unknown\x20command\x20`Content-Length:`,\x20with\x20a
SF:rgs\x20beginning\x20with:\x20`0`,\x20\r\n-ERR\x20unknown\x20command\x20
SF:`Contact:`,\x20with\x20args\x20beginning\x20with:\x20`<sip:nm@nm>`,\x20
SF:\r\n-ERR\x20unknown\x20command\x20`Accept:`,\x20with\x20args\x20beginni
SF:ng\x20with:\x20`application/sdp`,\x20\r\n");

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 162.88 seconds

Nmap try to perform some probes, but he really doesn't know what need to do.

You can check download original redis-rsm-nmap.txt.

Using Thc-Hydra

In the other hands when try to launch Hydra in our Redis-RSM server, hydra doesn't recognize them as a redis server:

> hydra -p passwords.txt -o hacked.txt redis://10.10.10.160:6379
Hydra v9.0 (c) 2019 by van Hauser/THC - Please do not use in military or secret service organizations, or for illegal purposes.

Hydra (https://github.com/vanhauser-thc/thc-hydra) starting at 2020-08-07 08:56:09
[DATA] max 1 task per 1 server, overall 1 task, 1 login try (l:1/p:1), ~1 try per task
[DATA] attacking redis://10.10.10.160:6379/
[ERROR] The server is not redis, exit.

Build a RSM map

Redis Security Mapper is a small tool for building RSM maps. It creates a map by using random names (UUID) as alias:

> rsm create-map
[*] Building new RSM map
    -> Saving new RSM map at: '/Users/USER/Documents/Projects/rsm/rsm.json'
[*] Done

You can also setup output file:

> rsm create-map -o rsm.json
[*] Building new RSM map
    -> Saving new RSM map at: 'rsm.json'
[*] Done

Add RSM map to redis.conf

redis-security-map allow you to add RSM alias in your redis.conf file:

> rsm redis-config

By default redis-security-map will find from running directory a redis.conf file and a rsm.json. If not redis.conf file is found will create new one.

You also can config custom RSM file and redis.conf file

> rsm -m examples/rsm.json -c examples/redis.conf

Launch redis with RSM

Docker

> ls
redis.conf
> docker run -v $(pwd)/redis.conf:/usr/local/etc/redis/redis.conf -p 6379:6379 redis /usr/local/etc/redis/redis.conf

Without Docker

> redis-server /examples/rsm/redis.conf

Redis SDK supported

Python

Redis Security Map integrated support for the two most used libraries in Python:

  • py-redis
  • aioredis

First you need to install redis-security-map dependency:

> pip install redis-security-mapper

Using RSM with py-redis

import os

from redis import Redis
from rsm.monkey_patch.pyredis import patch_pyredis

def main():
    here = os.path.dirname(__file__)
    rsm_file = os.path.join(here, "rsm.json")

    patch_pyredis(rsm_file)

    redis_con = Redis(decode_responses=True)

    redis_con.set("hello", "world")
    print(redis_con.get("hello"))

if __name__ == '__main__':
    main()

Using RSM with aioredis

import os
import asyncio

import aioredis

from rsm.monkey_patch.aioredis import patch_aioredis


async def main():

    here = os.path.dirname(__file__)
    rsm_file = os.path.join(here, "rsm.json")

    patch_aioredis(rsm_file)

    redis = await aioredis.create_redis_pool('redis://localhost')

    await redis.set('my-key', 'value')
    value = await redis.get('my-key', encoding='utf-8')
    print(value)

    redis.close()
    await redis.wait_closed()


if __name__ == '__main__':
    asyncio.run(main())

RSM file specification

File specification is easy. RSM file is a regular JSON file where each key is the Redis Command you want to map and value is the new value. Example:

{
  "XREVRANGE": "2a34187406384be59a33008e81c5a92d",
  "BLPOP": "8075de5f7bb94ab4b7024a857b74d7e3",
  "HGETALL": "854502babb1f48969cf020e7d79a6c07",
  "EXEC": "be08715620c242cb88df7a51c827b837",
  "BITFIELD": "43059bafe0d74db3970605134ab2ee4f",
  "XINFO": "8c6e90b9834e445bbed1372086e7a499",
  "LTRIM": "7686c57736d640c5aa387ca098816052",
  "DBSIZE": "6203f641eeef457fa40bff605cd29d67",
  "REPLCONF": "d234e97f54ba49ceb8f1ec580e032d87",
  "HSET": "958b9cb4e4cc4e89b0eccb50d88a5b7e",
  "SYNC": "01757da1afb3418390a6b28eb02e10fc",
  "GET": "1f608add63374251bfba8ee05f65c07b",
  
  ...
}

Contributing

Ideas and PR are welcome! Also:

If you are a Redis SDK client developer and want to add support for RSM... it should be nice!

License

This project is distributed under BSD license