Research and Development

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Zango Adware - Insecure Auto-Update and File execution


Ref : TZO-042006-Zango

I. Backround
http://www.zangocash.com

"ZangoCash (formerly LOUDcash) is recognized around the world as one of the best pay-per-install affiliate programs on the Internet. ZangoCash is a subsidiary of 180solutions which also includes Zango and MetricsDirect . Every day, 7,500-10,000 ZangoCash affiliates distribute our software to users who are then connected with more than 6,000 MetricsDirect advertisers."

II. Description
After the acknowledgement of an License Agreement, during Startup, the bundled EXE contacts several servers and downloads the required Adware components. The downloaded components are not checked for integrity or authenticity and are executed as soon as they are downloaded.

The Following procedures are exploitable :

  1. Initial Install
  2. Auto-Update function

The condition is exploitable in the following scenarios :

  1. You have legitimate control over the DNS server
  2. You have compromised a DNS server
  3. You forge a cache poisoning attack against a vulnerable DNS server
  4. You have access to the machine and change the HOST file

.Redirecting the hostname "static.zangocash.com" to an IP address under your Control and creating the respective V-host allows you to install any type of executable on the machine where zango is being installed or currently is installed, in other words: You could potentially compromise an internal network of a company if Zango is installed on workstations (or servers - i've seen that) and one of the 4 aforementioned conditions are met.

Why is this an Issue ?
Especially the auto update function is a problem, imagine a DNS server (not a split setup) is compromised or cache-poisened, every workstation with zango installed inside the company can be immediately compromised as the Workstation tries to automaticaly download an update of Zango and fails to realise that instead of Zango it downloads and executes a Rootkit/Backdoor/"put anything here".

 


Real-life Scenario (Dns Cache Poisening, compromise etc.)

 

Why alter the zango address and not update.microsoft.com ?

1 - The address of the micrososoft update servers is now hardcoded in the Operation System itself
2 - Microsoft signs and authenticates the files it downloads, it won't execute the files if it has been messed with or is not the original file. This has become the standard procedure in all auto-update functions I know of, several AV vendors do the same.


Threat ?

- The Auto update problem with Zango Adware remains, there was no fix.
- The Adware component is distributed by over 10.000 affilates everyday and I expect it to be installed on millions of   workstations (IMO).
- If you compromise (or alter) a DNS server this gives immediate access to internal client machines.

Mitigation ?

- Block access to static.zangocash.com or zangocash.com althogether at the firewall.

III. Proof of Concept


Proof of Concept Setup (Initial Install scenario)


Proof of Concept Setup (Update Scenario)

 

The Initial Install scenario allows the execution of files deployed on the same server. The update function seems to be used randomly querying the server for an existing XML file, if the file exists the file is downloaded, parsed, and the file referenced therein will be downloaded and executed.


Multiple execution of the downloaded ZangoInstaller.exe (calc.exe)


IV. Summary

Vendor contact : 01/02/2006
Vendor Response : 05/02/2006

Vendor Response :
No official statement, I was not given permission to disclose the email conversations that took place.

V. Download

TXT; PDF