Cleverly disguised flyers for internet services are a new crime risk

“Your internet bill will be cheaper and your communication speed will be faster than before.”

This was the message on a flyer found in a home’s mailbox. It was styled to look like an announcement from the condominium’s management company, and at first glance, it seemed entirely legitimate.

However, a chilling experience shared on social media has caused a significant stir: after trusting this flyer, contacting the company, and letting the representatives into their rooms, people reported that the visitors “went around looking at all the electrical outlets in the house.”

Is this malicious sales activity, or is the purpose to scout for burglaries or plant listening devices? This article explains the reality of these disguised internet flyers that are encroaching on our daily lives, the latest criminal risks lurking behind them, and self-defense measures.

Cleverly disguised flyers mimicking management companies, tricking even real estate agents

The internet service flyers that have gained attention on social media share a common characteristic.

Looking at actual flyer images, they feature stern wording such as “Important,” “To All Residents,” and “Announcement Regarding the Introduction of Communication Lines (10G Ultra-High-Speed Line) Equipment,” making them appear to be official notifications from the condominium’s management association or company.

Furthermore, they employ psychological manipulation tactics, such as setting deadlines like “Residents who can cooperate, please respond by Month X,” to pressure residents into contacting them.

On social media, many personal accounts and cautionary voices regarding this tactic can be seen.

“This is a very scary story. A flyer for an internet company came into my apartment building, advertising ‘It will be cheaper and faster than before’ with a new line installation. Since our building can only contract with a specific provider, many households, including my mom friends, called the company. Apparently, the representatives went around looking at all the electrical outlets in their homes.”

“I had a fake visit impersonating a collaboration with a famous internet provider. They said something nonsensical like ‘We support high-speed plans that haven’t been installed yet.’ When I refuted them, they left, and I suspect they might have shared information among themselves that ‘there are informed residents in that building.’”

Some cases are so sophisticated that they can even mislead real estate companies, which are supposed to be professionals.

“I also received such a flyer. When I asked about it at the real estate office I was visiting, they casually said, ‘Since the condominium name is on it, it’s probably an official flyer.’ I found it suspicious and searched for the company on the internet, and it turned out to be a shady company. I was disappointed with both.”

As seen, there are malicious tactics that impersonate management companies or famous internet providers and attempt to gain entry into residents’ rooms under the guise of legitimate procedures.

Cases where representatives inspect all electrical outlets in the house

In some cases, suspicious representatives who have entered a room do not proceed with internet line construction or router checks. Instead, they might say, “It’s not compatible with the standard, so we cannot contract,” and leave after inspecting all the electrical outlets in the house.

In the past, such incidents might have simply been failed attempts at fraudulent business practices. However, it is now frightening because they could be reconnaissance for burglaries by anonymous, mobile criminal groups.

This reminds me of a burglary case where the perpetrators had an unusually detailed understanding of furniture placement, floor plans, and the number of dogs kept in the house, suggesting reconnaissance by anonymous, mobile criminal groups.

“I teach my children that door-to-door sales or flyers offering low prices are basically bait to find targets for fraud or burglary.”

According to security information from Sogo Keibi Hosho (ALSOK), the inside of electrical outlets is a common place to install listening devices that can operate semi-permanently because they provide direct access to power. If the outer cover of an outlet is removed and a device is hidden inside, it becomes extremely difficult for residents to discover it visually.

Anxious voices are rising online.

“Electrical outlets are a classic spot for listening devices, so it’s terrifying.”

“If they went around looking at the outlets, could listening devices or something similar have been installed? My condominium also issued a warning about this flyer. The flyers keep coming, but when I investigated the company previously, it was not registered, and the address was in an unnatural location.”

Academic paper warns of the latest technique, eerie coincidence with fiber optic eavesdropping

While installing commercial listening devices or scouting for burglaries are long-standing tactics, recent research by experts has revealed an eerie coincidence between the actions of these fake internet service representatives tampering with electrical outlets (specifically, optical outlets) and the threat models of the latest advanced cyberattacks.

A paper titled “Hiding an Ear in Plain Sight: On the Practicality and Implications of Acoustic Eavesdropping with Telecom Fiber Optic Cables,” published by a research team from institutions including the Hong Kong Polytechnic University and the Chinese University of Hong Kong, has demonstrated the practicality of side-channel attacks that exploit the fiber optic cables themselves as vibration sensors (microphones) to eavesdrop on conversations within a room, rather than intercepting communication data.

In this paper, the research team warns of a terrifying attack scenario: attackers impersonating insiders at internet service providers or technicians/subcontractors gain physical access to the victim’s home and install a device called a Sensory Receptor in the optical outlet box located low on the wall to amplify sound. Through this device, human conversations from several meters away can be reconstructed with over 80% accuracy.

Of course, executing this latest eavesdropping technique requires connecting expensive, specialized equipment (a DAS system) from outside the house, making it closer to sophisticated espionage targeting specific individuals rather than a general burglar. However, the behavior pattern of fake technicians entering a room and attempting to tamper near wall outlets (optical outlets) perfectly matches the suspicious activities reported by users on social media. Whether it’s a physical listening device or the latest side-channel attack exploiting fiber optics, the danger of allowing unknown individuals near electrical outlets has been confirmed.

Self-defense measures to avoid being deceived: Utilize the Ministry of Internal Affairs and Communications list

How can one protect themselves from these sophisticated tactics and repel suspicious individuals before letting them into their homes?

If you feel uneasy, you can verify the company based on official government systems.

In Japan, businesses that conduct telecommunications services, such as internet lines, or operate as sales agents for them are required by the Telecommunications Business Act to register or file with the Ministry of Internal Affairs and Communications.

Legitimate businesses will have their company name and registration number listed in directories such as the list of registered telecommunications businesses published by the Ministry of Internal Affairs and Communications.

Wise users on social media are also seen performing this verification process for self-defense.

“I often receive such flyers at my home. I check the company name, and if it’s not from the management company, I ignore it.”

Even if you receive a flyer with attractive wording promising lower prices, you should not blindly trust the company name, such as “XX Communications Co., Ltd.,” listed on it.

First, directly confirm with the real estate management company whether this is an official construction approved by the entire condominium. Then, it is important to check if they are a registered legitimate business listed on the Ministry of Internal Affairs and Communications’ list.

Flyers that use low prices as bait could be an entry point to crimes that threaten your property, privacy, and even your life.

Needless to say, never let unknown individuals into your home – this fundamental rule of crime prevention should be shared with the entire family.

Disclaimer

Opinions from the internet have been edited for presentation within the context of the article.