It is Tribord. They are a French brand. For a while they were sold in the USA by Decathlon Sports, a chain in the New England area (owned by a French company). Decathlon went out of business in the US, but it looks like Tribord is still around (link below). Not sure if they still make the briefs in the picture. When Decathlon went out, I bought a bunch of pairs of Tribord briefs. They are cut very narrow and low, just like the picture. They fit awesome. I think I have one or two still left.
http://www.tribord.com/
Let us know if you find them.