Now, the Suicide Squad artwork is chock-full of photo reference, so I wonder what the true source is? (My guess: pinup/porn). Either way, it appears the GIJoe poster artist either swiped from Michael Bair's Suicide Squad cover, or the same referenced photo.... or just had someone do the same pose in the Baroness outfit.
*A No-Prize for each source image found for the Suicide Squad cover!*
UPDATE: Just ran across 2004's Daredevil #64 cover by Alex Maleev... not the same, but what are the odds of seeing these 3 images in the same week?!