That ship may have already sailed. They could've pulled a decent "honestly, we had no idea!" excuse pre-2013, when only most of the cryptography community assumed the Dual EC was both backdoored and useless for its intended purpose, but not after it was confirmed by Snowden's documents that the NSA backdoored Dual EC, and yet they continued to use it.
And now, when they found out a(nother) nation state was using it, their "fix" is to change the parameters again instead of burning it with fire. That's strike three.
So I'm not convinced that the blame for this backdoor can be placed on Juniper's shoulders.
Even if it weren't, why would it be reasonable to allow critical cryptographic components to go unaudited for 8 years? If the analysis so far is correct, then a single independent test vector for the RNG should have caught this bug. One. Lousy. Test. Furthermore, the fact they discussed their use of DualEC in 2013, and then claimed their construct was secure, is proof they were aware of the danger and yet, apparently, they hadn't done anything to verify this.
Hanlon's razor is going to condemn them one way or another here. Unless they can demonstrate extraordinary circumstances, then Juniper security products should be considered toxic.
Most firms didn't even start getting basic software security assessments done until ~5 years ago, and almost nobody gets crypto reviews done (crypto reviews are nosebleed expensive, because only a tiny fraction of software security people can do them competently).
ScreenOS has been FIPS-140 validated a couple of times in the last 10 years...
Also: FIPS validation isn't particularly meaningful. It's not like a serious crypto assessment.
> The attacker also replaced some test vectors.
The ball is in Junipers court now: to prove they are merely incompetent and not outright malicious.