The image is taken from the Rising Sun Emblem, which VE was the first to use in all of the Cyberverse. TOOL's current flag actually came after the VE started the OE, which looks so similar that, if these images were worth money, could probably be tried a legal copyright issue.
For reference: OE flag
http://images1.wikia.nocookie.net/cybernat.../2/2e/Oeff5.png
Dark version of rising sun emblem, Dual Hammars and Imperial Eagle over Black/white moon image.
TOOL flag:
http://homepage.eircom.net/~wolfhead/TOOL%20Flag.jpg
Dark version of rising sun emblem with 3D effects, Arm and hammar over black/white image.
Veeeeeery similar Its no big deal though. I believe Umbrella and another alliance also use the Rising sun emblem, and iFOK uses a modification of the rising sun for their flag.