"Quacking" is the process of Hacking via the increasingly popular "QR Code" system

How does it work?

Basically QR Codes are used to link to a logo, site or body of text from a device with a reader application (Think IPhone, Android etc)

imagine if you could redirect QR Code to a malware site - for example a PDF File embedded with a jailbreak exploit?

Social engineering with QR Codes:

How about leaving QR Codes near a place of work that links to malware of your choice? what curious employee isnt going to try to see what the curious symbol pasted to the door, wall, car, floor etc near their place of work is about?

QUACKING - you would be Quackers to fall for it!

QR code

A QR code (abbreviated from Quick Response code) is a specific matrix barcode (or two-dimensional code) that is readable by dedicated QR readers, smartphones, and, to a less common extent, computers with webcams. The code consists of black modules arranged in a square pattern on a white background. The information encoded may be text, URL, or other data.

Common in Japan, where it was created by Toyota subsidiary Denso Wave in 1994, the QR code is one of the most popular types of two-dimensional barcodes. The QR code was designed to allow its contents to be decoded at high speed.

Although initially used for tracking parts in vehicle manufacturing, QR codes now are used in a much broader context, including both commercial tracking applications and convenience-oriented applications aimed at mobile phone users (termed mobile tagging). QR codes may be used to display text to the user, to add a vCard contact to the user's device, to open a Uniform Resource Identifier (URI), or to compose an e-mail or text message. Users can generate and print their own QR codes for others to scan and use by visiting one of several paid and free QR code generating sites or apps.

QR codes storing addresses and Uniform Resource Locators (URLs) may appear in magazines, on signs, buses, business cards, or almost any object about which users might need information. Users with a camera phone equipped with the correct reader application can scan the image of the QR code to display text, contact information, connect to a wireless network, or open a web page in the telephone's browser. This act of linking from physical world objects is termed hardlinking or object hyperlinking.

QR codes can be used in Google's mobile Android operating system via both their own Google Goggles application or 3rd party barcode scanners like ZXing or Kaywa. The browser supports URI redirection, which allows QR codes to send metadata to existing applications on the device. Nokia's Symbian operating system is provided with a barcode scanner, which is able to read QR codes,[3] while mbarcode[4] is a QR code reader for the Maemo operating system. In the Apple iOS, a QR code reader is not natively included, but more than fifty paid and free apps are available with reader and metadata browser URI redirection ability. With BlackBerry devices, the App World application can natively scan QR codes and load any recognized Web URLs on the device's Web browser. Windows Phone 7 will be able to scan QR codes through the bing search app in the upcoming Mango update.