Hacking

Stealth Cell Tower, how to spy on workers with a harmless printer

Stealth Cell Tower, it is an antagonistic GSM base station concealed in an office printer that could be used for surveillance purposes.

Are you angry with your boss or your colleagues? Do you want to spy on them? The engineer Julian Oliver has demonstrated how to do it with a tiny cellphone base station concealed in an apparently innocuous office printer.

Oliver dubbed his project Stealth Cell Tower, it is an antagonistic GSM base station concealed in an office printer.

The expert explained that the Stealth Cell Tower is part of an ongoing research on the practice of disguising cell towers as other things (i.e. like trees or church spires), in 2014 he wrote an interesting article titled “Stealth Infrastructure.”

Here, Stealth Cell Tower situates this same outdoor practice indoors, where an HP printer is perhaps the most innocuous of flora.

“Stealth Cell Tower is an antagonistic GSM base station in the form of an innocuous office printer. It brings the covert design practice of disguising cellular infrastructure as other things – like trees and lamp-posts – indoors, while mimicking technology used by police and intelligence agencies to surveil mobile phone users.” reads a blog post on the project.

Oliver used a common HP Laserjet 1320 because it has a helpful free space inside the casing, then assembled inside the device a RaspberryPi 3 with a couple of antennas, the BladeRF SDR board and some cabling to power these components.

The complete list of the hardware used by the expert includes:

  • A Hewlett Packard Laserjet 1320 printer modified to contain and power components
  • BladeRF x40
  • Raspberry Pi 3
  • 2x short GSM omnidirectional antennae with magnetic base
  • 2x SMA cable
  • Cigarette-lighter-to-USB-charger circuit (converting 12-24v to 5v)
  • 1x USB Micro cable (cut and soldered to output of USB charger)
  • 1x USB A cable (cut and soldered to printer mainboard)

 

Oliver explained that the Raspberry Pi 3 was chosen after failed attempts to achieve stable YateBTS performance on the Intel Edison, Beaglebone Black and I-MX6 Marsboard, that were first choices due to their small footprint.

“The Raspberry Pi 3 was chosen after failed attempts to achieve stable YateBTS performance on the Intel Edison (tiny – would’ve saved space!), Beaglebone Black and even an I-MX6 Marsboard,” he wrote. “Unlike the antiquated OpenBTS, YateBTS really seems to need those extra cores, otherwise ignoring accelerators like NEON on the Cortex A8/9 platforms.”

The core of the experiment is the code written by Oliver and running on the tiny PC, it operates as a bogus cellphone tower that detects nearby phones and sends them SMS messages.

“Masquerading as a regular cellular service provider, Stealth Cell Tower surreptitiously catches phones and sends them SMSs written to appear they are from someone that knows the recipient. It does this without needing to know any phone numbers.”

The Stealth Cell Tower is able to print for each response to the above messages a transcript that includes various information such as the captured message sent, the victim’s unique IMSI number and other identifying data. The printer also randomly calls victim’s phones in the environment and on answering, Stevie Wonder’s 1984 classic hit I Just Called To Say I Love You is heard.

It is clear that a similar configuration could be used in a real attack scenario, for example by sending out phishing SMS messages or to perform man-in-the-middle attacks against workers.

In short, it could become a very powerful surveillance device, the next time you mount a printer in the office, look inside.

You can download the full code used by the expert here (sha256sum eaabeb72eb5bf3e62cbfedb43dbc623437b40728b25555d88c9e8f06ca31d090).

[adrotate banner=”9″]

Pierluigi Paganini

(Security Affairs – Stealth Cell Tower, espionage)

Pierluigi Paganini

Pierluigi Paganini is member of the ENISA (European Union Agency for Network and Information Security) Threat Landscape Stakeholder Group and Cyber G7 Group, he is also a Security Evangelist, Security Analyst and Freelance Writer. Editor-in-Chief at "Cyber Defense Magazine", Pierluigi is a cyber security expert with over 20 years experience in the field, he is Certified Ethical Hacker at EC Council in London. The passion for writing and a strong belief that security is founded on sharing and awareness led Pierluigi to find the security blog "Security Affairs" recently named a Top National Security Resource for US. Pierluigi is a member of the "The Hacker News" team and he is a writer for some major publications in the field such as Cyber War Zone, ICTTF, Infosec Island, Infosec Institute, The Hacker News Magazine and for many other Security magazines. Author of the Books "The Deep Dark Web" and “Digital Virtual Currency and Bitcoin”.

Recent Posts

FBI chief says China is preparing to attack US critical infrastructure

China-linked threat actors are preparing cyber attacks against U.S. critical infrastructure warned FBI Director Christopher…

4 mins ago

United Nations Development Programme (UNDP) investigates data breach

The United Nations Development Programme (UNDP) has initiated an investigation into an alleged ransomware attack…

2 hours ago

FIN7 targeted a large U.S. carmaker with phishing attacks

BlackBerry reported that the financially motivated group FIN7 targeted the IT department of a large…

14 hours ago

Law enforcement operation dismantled phishing-as-a-service platform LabHost

An international law enforcement operation led to the disruption of the prominent phishing-as-a-service platform LabHost.…

19 hours ago

Previously unknown Kapeka backdoor linked to Russian Sandworm APT

Russia-linked APT Sandworm employed a previously undocumented backdoor called Kapeka in attacks against Eastern Europe since…

24 hours ago

Cisco warns of a command injection escalation flaw in its IMC. PoC publicly available

Cisco has addressed a high-severity vulnerability in its Integrated Management Controller (IMC) for which publicly…

1 day ago

This website uses cookies.