A new investigation has revealed a problem related to mobile networks, in which under some circumstances the IMEI number of the phone can reach the caller even before the call is picked up.

We typically consider a normal phone call to be merely a means of communication, but a new investigation has raised concerns about the security of mobile networks. According to the report, in some circumstances, technical information related to a phone can reach the caller even before the call is received. This could include information such as the smartphone's 15-digit IMEI number, the phone model, and the operating system version. This has now raised the risk of some important phone information being leaked even without the call being answered. So, let's explore how an IMEI can be leaked simply through a call.

How can IMEI be leaked just by a call?

According to an investigation by Bayerischer Rundfunk (BR), this problem occurs when calls are made between users of two different mobile networks. BR investigated the problem by conducting 70 test calls on Germany's Telekom, Vodafone, and Telefónica (O2) networks. The report stated that in many cases, the IMEI number was revealed to the caller on Telekom and Telefónica (O2) networks. Meanwhile, the model and operating system version of the smartphone were revealed on Telekom and Vodafone networks. However, Vodafone clarified that the IMEI number was not revealed in the tests conducted on its network.

Why is leaking of IMEI number a matter of concern?

The IMEI is a unique number that identifies a mobile device. According to BR, this information can be used to profile devices, conduct more targeted phishing and social engineering attacks, and identify devices and software that may have security flaws.

A test call was also made to the phone of former German military officer and Bundestag member Roderich Kiesewetter. He confirmed that the IMEI number displayed was the correct one for his phone. Germany's Federal Office for the Protection of the Constitution also confirmed the matter and acknowledged that intelligence agencies could misuse such information.

More than 1,000 operators have been warned.

Following the incident, the Global System for Mobile Communications Association (GSMA) alerted more than 1,000 mobile network operators. The GSMA advised companies to audit their networks and filter out unnecessary data transmissions.

Leak fixed in Germany

Following the report, German mobile network operators have announced technical changes to address the issue. However, BR's investigation was limited to German networks, so it remains unclear whether similar issues exist in mobile networks in other countries. The IETF's RFC 7254 and RFC 7255 also warn about IMEIs. They state that IMEIs can be used for device identification and tracking, and that publicly disclosing them could compromise user privacy.

PC: ABP News