Just found this unmarked HDMI female-to-male HDMI "patch"-style cord

Question

It's only my wife and I in our house (two years now) and we don't regularly have any guests over. My wife isn't super tech-literate and doesn't make any purchases on household electronics, and I certainly don't remember ever buying anything like it (unless it comes with Fire Sticks stock), yet I found it connected between our Fire Stick 4K and display.

I know there are such things as USB data/key loggers, but is there any such concerns for an unidentified in-the-middle HDMI device like this? The only functional purpose I can see it serving is for the extremely specific case where you may have less room than the legth of the Stick itself from the port to the wall, but even then it's quite strange that there no markings or print on it. Just want to make sure, what's the worse case from a data security standpoint?

Answer 1

If you Google "short HDMI male to female extender" you will see these devices are fairly common, sometimes provided with equipment and most likely benign. Searching "firestick HDMI extender" also shows these, and the results imply that some.midels of firestick indeed included such a cable.

They can be used to remove stress from plugging and unplugging a cable and can make connecting a cable through a difficult spot easier (like through a smallish hole in the back of a TV cabinet). Similarly, they often have a tight bend radius making them easier to re-orient a cable with limited clearance than a large cable.

While it is possible that there is something questionable about the cable it is most likely not being used for sniffing as HDMI signals transmit a lot of data, so it would likely need to dump this to storage on the device for later retrieval, and would not be particularly helpful with things like sniffing passwords as they are not displayed. (compared to keylogging which deals with fewer data and captures passwords) You also have physical size difficulties and retrieval difficulties. A key logger would typically be a better choice to compromise a system, otherwise, an attacker might be better off doing Van Eck phreaking to remotely read the contents of the screen - likely less difficult to remotely read the screen from its radio interference then recover (and possibly decrypt) and HDMI output.