After a previous breach in August where nearly 50 million customer data were leaked, T-Mobile suffered another data breach, this time less severe. It has affected only a small subset of customers.
Three Categories of Customers Affected
A customer may have only been affected by a leak of their CPNI. This information may include the billing account name, phone numbers, number of lines on the account, account numbers, and rate plan info. That’s not great, but it’s much less of an impact than the breach back in August had, which leaked customer social security numbers.
The second category an affected customer might fall into is having their SIM swapped. This is where a malicious actor will change the physical SIM card associated with a phone number in order to obtain control of said number. This can, and often does, lead to the victim’s other online accounts being accessed via two-factor authentication codes sent to their phone number. The document says that customers affected by a SIM swap have now had that action reversed.
The final category is simply both of the other two. Affected customers could have had both their private CPNI viewed as well as their SIM card swapped.
T-Mobile Acknowledges the Breach
T-Mobile has now publicly acknowledged the latest breach.
We informed a very small number of customers that the SIM card assigned to a mobile number on their account may have been illegally reassigned or limited account information was viewed. Unauthorized SIM swaps are unfortunately a common industry-wide occurrence, however this issue was quickly corrected by our team, using our in-place safeguards, and we proactively took additional protective measures on their behalf.
T-Mobile Spokesperson to Bleepingcomputer
