To be relevant in copyright protection scenarios, watermarking systems need to provide appropriate levels of security. This paper investigates the security of a popular 3D watermarking method that alters the histogram of distances between the vertices of a surface mesh and its center of mass using a quadratic programming formulation.We study two conventional security mechanisms, namely (i) obfuscating the support of the content used for watermarking and (ii) relying on random projections to obfuscate the watermarking subspace. The different attacks surveyed throughout the paper clearly highlight the limitations of this family of 3D watermarking systems with respect to security.