Pierluigi Paganini May 24, 2016

The FBI issued a notification warning actors in the private sector about a rapid diffusion of KeySweeper, a keystroke loggers disguised as USB phone chargers.

The FBI is warning actors in the private sector about a rapid diffusion of stealthy keystroke loggers disguised as USB phone chargers.

The FBI issued a Private Industry Notification warning of the abuse of KeySweeper components that are able to sniff everything users type into wireless keyboards.

I have written about KeySweeper around 15 months ago when the creator, the ingenious Samy Kamkar released the project.

“KeySweeper is a covert device that resembles a functional Universal Serial Bus (USB) enabled device charger which conceals hardware capable of harvesting keystrokes from certain wireless keyboards”  reads the FBI’s alert.” If placed strategically in an office or other location where individuals might use wireless devices, a malicious cyber actor could potentially harvest personally identifiable information, intellectual property, trade secrets, passwords, or other sensitive information. Since the data is intercepted prior to reaching the CPU, security managers may not have insight into how sensitive information is being stolen.”

Samy Kamkar designed a cheap USB wall charger that can eavesdrop on almost any Microsoft wireless keyboard, KeySweeper is a stealthy Arduino-based device that works like a generic USB mobile charger, but he has the capability to sniff, decrypts and send back keystrokes from a Microsoft wireless keyboard in the vicinity. KeySweeper can send captured data back to the operator over the Internet or using an optional GSM chip.

As explained by Kamkar, this kind of devices is very simple to assemble and are very cheap, the hardware necessary to build a KeySweeper is reported below:

• $3 – $30: An Arduino or Teensy microcontroller can be used.
• $1: nRF24L01+ 2.4GHz RF Chip which communicates using GFSK over 2.4GHz.
• $6: AC USB Charger for converting AC power to 5v DC.
• $2 (Optional): An optional SPI Serial Flash chip can be used to store keystrokes on.
• $45 (Optional): Adafruit has created a board called the FONA which allows you to use a 2G SIM card to send/receive SMS, phone calls, and use the Internet directly from the device.
• $3 (Optional if using FONA): The FONA requires a mini-SIM card (not a micro-SIM).
• $5 (Optional, only if using FONA): The FONA provides on-board LiPo/LiOn battery recharging, and while KeySweeper is connected to AC power, the battery will be kept charged, but is required nonetheless.

The FBI’s notification makes no reference to specific cases where criminals used the sniffing device.

Microsoft confirmed that sniffing attacks could be effective against any wireless device that doesn’t protect communication by encrypting data in transit, for this reason, any keyboards manufactured after 2011 is today protected by the use of the Advanced Encryption Standard.

The FBI notification also includes precious suggestions of the defense of corporations, first of all, the restriction for the use of wireless keyboards.

If the use of a wireless keyboard cannot be prevented, then be sure the device uses a strong encryption for the data transmission.

“A keyboard using AES encryption makes it more difficult to read keystrokes as there are currently no known practical attacks to read AES encrypted data.” states the notification. “Keyboards using Bluetooth are also safe from KeySweeper as it listens on a different channel than that which Bluetooth transmits. However, Bluetooth keyboards must have encryption turned on and a strong pairing PIN to protect it from a similar type of data-harvesting attack.”

• Additional best practices included in the note are:
• Limiting which outlets are available for device charging
• Knowing whose chargers are currently being used
• Immediate removal of an unknown charger from the office facility (although the optional backup battery can allow data theft even when unplugged)

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Thank you

Pierluigi

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Pierluigi Paganini

(Security Affairs – KeySweeper, FBI)