QR codes: How they work and why they can be dangerous to your cell phone

QR codes: How they work and why they can be dangerous to your cell phone

These are small black and white squares that are displayed on tables and boxes in various commercial spaces and store information that should be displayed on cell phones.

QR codes have been widely recognized around the world in the wake of the corovirus pandemic.
QR codes have been widely recognized around the world in the wake of the corovirus pandemic.

Among the many changes brought about by the pandemic is that Extensive use of QR codesGraphic representations of digital data that It is possible to print and then scan Together Smartphone Or other device.

The QR codes Has a wide range of uses Help people avoid contact with objects and close interactions Share with others, including restaurant menu, email list signatures, car and home sales information, and check-ups for medical and professional meetings.

The use of QR codes has spread along with the pandemic
The use of QR codes has spread along with the pandemic

QR codes Are close cousins ​​of barcodes On product packages carried by cashiers with infrared scanners to let the registry know what products are being purchased.

Barcodes store information along a single axis, horizontally. QR codes store information on both the vertical and horizontal axes, Which allows them to store much more data. This extra amount of data is what makes QR codes so versatile.


While it is easy for people to read Arabic numerals, it is difficult for a computer. Barcodes encrypt alphanumeric data As a series of black and white lines of different widths.

In-store barcodes write a set of numbers that identify the product. Critically, The data stored in the barcodes is redundant. Even if part of the barcode is destroyed or obscured, the device can still read the product ID.

QR Free App Download Acute Art
QR Free App Download Acute Art

QR codes are designed for scanning by the camera, As found on your smartphone. QR code scanning is built into many Android and iOS camera apps. QR codes Most often used to store web links. However, they can store arbitrary data such as text or images.

When you scan a QR code, the QR reader in your phone’s camera encrypts the code and the information received triggers the action on your phone. If the QR code has a URL, your phone will show you the URL. Touch it and your phone’s default browser will open the web page.

QR Code Anatomy

QR codes consist of several parts: data, replacement fields, silent zone, and optional logos. QR code data is a series of dots on a square grid. Each dot represents one and each blank space is zero in the binary code, and templates encode numbers, letters, or a combination of both, including URLs.

In its smallest form, this grid has 21 rows with 21 columns.And in its largest form it has 177 rows with 177 columns.

In most cases, QR codes use black squares on a white background, making it easier to distinguish dots. However this is not a strict requirement and QR codes can use any color or shape for dots and backgrounds.

Placeholders are squares located in the upper left, upper right and lower left corners of a QR code. These markers allow the camera to a Smartphone Or another device that targets the QR code by scanning it.

QR codes have a great variety
QR codes have a great variety

QR codes are surrounded by a blank space, a quiet zone, to help the computer determine where the QR code begins and ends. QR codes can be included in the middle of an optional logo.

Like barcodes, QR codes are designed with an abundance of data. Even if 30% of the QR code is destroyed Or hard to read, Data recovery is still possible.

In fact, logos are not part of the QR code; Hide some data from the QR code. However, due to the abundance of QR code, the data presented with these missing points can be recovered by viewing the remaining visible points.

Are QR codes dangerous?

QR codes are not inherently dangerous. They are just a means of storing data. However, just as clicking on email links can be dangerous, visiting URLs stored in QR codes can also be dangerous in many ways.

The QR code URL may take you to a website Phishing Who is trying to deceive you Enter your username or password for another website. The URL may take you to a legitimate website and trick that website into doing something harmful, such as giving an attacker access to your account.

While such an attack requires a flaw in the website you are visiting, such vulnerabilities are common on the internet. url Can take you to a malicious website Which deceives another website into which you are logged in to the same device in order to perform an unauthorized action.

QR Code Anatomy: 1;  Date 2;  Seat owners 3;  Quiet Zone 4;  Optional logos.
QR Code Anatomy: 1; Date 2; Seat owners 3; Quiet Zone 4; Optional logos.

Malicious URLs may open an app on your device and cause it to take effect. You may have seen this behavior when you clicked on the Zoom link and the Zoom app opened and automatically joined the meeting.

While such behavior is usually benign, an attacker could use it to trick some apps into exposing your data. It is important that when you open a link in a QR code, you make sure that the URL is secure and comes from a trusted source..

Just because a QR code has a logo that you are familiar with does not mean that you have to click on its URL. also There is a small chance that the app used to scan the QR code contains vulnerabilities that allow malicious QR codes to invade your device.

This attack will be successful by simply scanning the QR code, even if you do not click on the link stored in it. To avoid this threat, you need to use trusted apps Provided by the device manufacturer to scan QR codes and prevent downloading of customized QR code apps.

BBC World

Source: La Nacion