  In a paper of P. Paillier and J. Villar a conjecture is made about the
malleability of an RSA modulus. In this paper we present an explicit algorithm
refuting the conjecture. Concretely we can factorize an RSA modulus n using
very little information on the factorization of a concrete n' coprime to n.
However, we believe the conjecture might be true, when imposing some extra
conditions on the auxiliary n' allowed to be used. In particular, the paper
shows how subtle the notion of malleability is.
