Of more than 1,600 Global 2000 firms, only 3% of their public-facing servers have been fully and properly locked down from the Heartbleed vulnerability that was first revealed nearly three months ago, new data shows.

While fewer than 1% of the external-facing servers at these enterprises remain fully vulnerable to Heartbleed, some 97% are only partially remediated from the threat, mostly because they failed to replace the private key, or revoke the old digital certificate. By not replacing the private key, an attacker could decrypt SSL traffic from the host, and by failing to revoke the old cert, an attacker could use it in phishing attacks, according to the July 2014 status report by Venafi.

"Heartbleed has been known to the world for 11 weeks now. Yet we still see evidence of thousands of systems susceptible to Heartbleed that have not even been patched yet," says Kevin Bocek, vice president of security strategy and threat intelligence at Venafi, in an email interview. "We believe this is partly due to a 'patch-and-move-on' mentality amongst IT professionals, meaning that once the patch is addressed, they believe the security hole is plugged. This approach is something that must be changed because as attacks continue to evolve and become more sophisticated, remediation becomes more extensive requiring multiple steps aside from just patching the vulnerable system."

But Robert Graham, CEO of Errata Security, says he's skeptical of the data in the report, and that it distorts the issue. He says his own scans show that 90% of externally facing sites don't use OpenSSL in the first place, so they had no reason to revoke and reissue keys.

He says the big issue is about organizations not revoking the at-risk digital certificates. "The paper doesn't mention the exact breakdown, but it's likely that the primary issue is lack of revocation of existing certificates. That is indeed something that many affected organizations haven't done, but should do," he says.

Dan Kaminsky, chief scientist at WhiteOps, says corporations have better processes in place for patching their internal servers than for working with third parties such as certificate authorities. "With an absence of evidence that keys were actually compromised, it wouldn't be surprising that the internal code was updated while the external dependency -- the new certs -- was left unaddressed," Kaminsky says.

He says it's unclear in the report whether the certificates are CA-originated ones or not. "Self-signed certs don't really offer much security at all, Heartbleed or not," he notes.

[Heartbleed wasn't the first security hole discovered in SSL deployments, and it won't be the last. Read SSL After The Heartbleed.]

Meanwhile, the risk of bad guys pilfering private keys was fairly low, says Ivan Ristic, director of Qualys's SSL Labs. That may also explain why organizations appear not to be taking the certificate issue as seriously, he notes.

The full report is available here (PDF) for download.