Ripple and Ringing from Cheap Chinese Boost Converter
Only illustrating the comment of Mr. John D., I would suggest you to visit this link: http://www.edn.com/design/power-management/4411821/Testing-a-power-supply---Noise--Part-2--

Figure 1 (specially on the right) shows one of the best ways to measure ripple/noise.

Your first picture shows a noise frequency close to 12MHz. I guess that the 7812 won't be able to control or kill this frequency. Your option is to attenuate the noise before it arrives to the 7812 input.

Supposing that you will always use the 1m wire length and also always in the same position:  the 1m wire is probably working as a transmission line. Twist the wires (in order to create a common mode inductor) and add 100nF ceramic chip capacitors between ground and positive of each side of the wire may help.

Hope this text can help you a little bit.

Best regards