Is there any more information on this RSA backdoor?
Actually, if the RSA key generation is malicious, there are even more subtle ways that can someone can leak the key.

The cleverest way I've seen works like this (assuming that we're generating an RSA-1024 key; for RSA-2048, we just use a larger curve):


The attacker generates an EC public/private key pair; using a 192 bit curve for RSA-1024 is good.  He keeps the EC private key secret; he'll install the EC public key into the program below.
To generate a key, the program selects a random 192 bit seed $R$.
It uses that seed to see a process that selects a random 512 bit prime $P$.
It encrypts the seed $R$ using the EC public value (perhaps using EC-ElGamal), resulting in a 384 bit value $E$.
It then selects a 512 bit prime $Q$ with the constraint that $Q \equiv P^{-1}(2E+1) \pmod{2^{385}}$
The product $PQ$ is the RSA modulus (and the rest of the RSA key pair is generated normally) 


Then, the attacker can easily factor this RSA key (by extracting $E$ directly from the bit pattern of the RSA modulus, using the EC private key to decrypt it resulting in $R$, and then using R to recover $P$.  And, no one without the EC private key has any advantage to factor this, even if they know the exact procedure used to generate the RSA key; both $P$ and $Q$ were chosen fairly, and the additional constraints on $Q$ do not help the attacker at all.

The moral of this story: if the attacker can control your RSA key generation process, you may have no security.