TrickBot Has Evolved to Become More Dangerous

TrickBot has been an active botnet since around October 2016. It's well known as part of the threat landscape, and has been operated in the past by GOLD BLACKBURN.

The trick to it is that it can manipulate web sessions by intercepting network traffic before it is rendered by a victim's browser. It fools you.

Secureworks, Inc. has found new activity by TrickBot that leaves mobile users in the US open to a new form of attack. They found that TrickBot is injecting code with different optimizations.

In their blog post about it, they say that, "In August 2019, the dynamic webinjects used by TrickBot were augmented to include the following US-based mobile carriers:

August 5: Verizon Wireless
August 12: T-Mobile
August 19: Sprint."

OK, TrickBot jumped on the three carriers. But what did it do to them? Secureworks saw that the injected code (that happened when the web sites of the above carriers were visited) caused an additional form field to be created which requests the user's account PIN code.

They note in the post that, "the legitimate server response is intercepted by TrickBot and proxied through a command and control (C2) server. This C2 server injects additional HTML and JavaScript into the page, which is then rendered in the victim's web browser." That's where the field for the PIN comes from.

The bot knows what to do with the PIN it snarfs too. TrickBot's record (rcrd) functionality is invoked at this point to create an additional HTTP request that contains the victim's username, password, and PIN. The request is transmitted to the TrickBot C2 server. These "recordings" are presented to TrickBot operators as they browse through infected hosts in their web panel.

Securework's take on this is that it "suggests an interest in perpetrating port-out or SIM swap fraud. This fraud allows an attacker to assume control of a victim's telephone number, including all inbound and outbound text and voice communications. The interception of short message service (SMS)-based authentication tokens or password resets is frequently used during account takeover (ATO) fraud."

The researchers also recommend that organizations use time-based one-time password (TOTP) multi-factor authentication (MFA) rather than SMS MFA when feasible. SMS MFA was the method the Social Security Administration had to scrap about a year ago because, as can be seen by the last paragraph and some advisories from CERT, it's easy to fraud.

Similarly, telephone numbers should not be used as password reset options on important accounts.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.