Mass. Gen. Laws ch. 106, § 9-601
(a) Rights of secured party after default. After default, a secured party has the rights provided in this part and, except as otherwise provided in Section 9–602, those provided by agreement of the parties. A secured party:
(e) Lien of levy after judgment. If a secured party has reduced its claim to judgment, the lien of any levy that may be made upon the collateral by virtue of an execution based upon the judgment relates back to the earliest of: