A devastating five-year old vulnerability in basic authentication systems may finally have a solution -- but it's really hard.

Typically, encryption and other IT security solutions rely on the fundamental presumption that the very first step of user authentication works and can be fully trusted. Kerberos -- a ubiquitous, decades-old authentication mechanism -- represents the core of how identity authentication works throughout the majority of enterprises worldwide. As such, it represents the roots of a tree of trust.

It is imperfect, however.

"They're all premised on this not being a lie," Jason Crabtree, CEO of data-analytics startup Qomplx (pronounced "complex"), told Security Now. "It's actually a terrible assumption to make... It doesn't mean that a single one of the authentication events is real."

Researchers at Black Hat 2014 revealed what is known as a "Golden Ticket" attack -- an exploit related to privilege-escalation attacks by forging not only tickets but also creating a forged key distribution center. For IT administrators of Windows and Linux environments that rely upon Kerberos, it is the curse that keeps on cursing.

Not much has been done about this vulnerability over the past few years -- largely because not much can be done about it. Like, to some extent, SPECTRE and MELTDOWN, the problem of Kerberos authentication has become something of a pink elephant in an otherwise well-appointed drawing room. It is very clearly there, but is impolite to talk about.

For some, the threat has been overblown. Not long after the Black Hat 2014 revelations, Roger Grimes of CSO Online argued that by applying mega-strict authentication policies bordering on draconian, just about everything can be accomplished on an enterprise network with task delegation and time limits on higher-level accounts.

"You want to make it hard for attackers to get domain admin status? Don't have any," wrote Grimes. "The most secure companies in the world have zero permanent members of their highly elevated groups [and] alert when anyone tries to add accounts to those groups."

Not everyone agrees that this is a complete solution, however. While Crabtree affirms that limiting credentials and maintaining a well-configured network are best practices, he claims that Qomplx has demonstrated a proof of concept involving ticket forgeries in the absence of permanently installed high-level users; from there, attackers were able to issue themselves these high levels of authority -- and then compromise cloud-based accounts.

Otherwise sophisticated UEBA solutions, Crabtree further explains, are likewise insufficient to counter the threat of Kerberos-authentication forgeries.

"It's like buying a seatbelt that works below 10 miles per hour and not above," said Crabtree. "It only works against adversaries that are unskilled enough that they don't bother to do the first thing a skilled adversary does -- which is [to] attribute the traffic to the wrong identification; [this] violates your ability to pinpoint any of this traffic in a behavioral basis."

Consequently, Qomplx -- which has historically been an analytics firm working with big data nonspecific to cybersecurity -- has taken the approach of going beyond metadata analysis.

The state of Kerberos authentication
The exodus from other modes of authentication to Kerberos began in the 1990s, for it solved an important problem: How do you keep authentication secure yet still properly agile -- so that the user doesn't have to manually authenticate themselves dozens or hundreds of times in a business day on the enterprise network. Unlike other authentication tools, Kerberos is a stateless protocol -- allowing one domain controller to issue a credential that can then be presented to and accepted by other domain controllers, while making ticket forgeries more difficult for attackers.

Attackers have solved this problem, however. In turn, Qomplx purports to have solved that problem in a complex (some might say "artless") way: by collecting, keeping a ledger of, and validating "every single Kerberos transaction" -- comparing known lists of valid tickets against every new authentication requests.

Describing the process as "stupid hard," Crabtree explained that Qomplx temporarily infuses statefulness into the otherwise stateless Kerberos protocol throughout the IT network. This is because the "handshake" that occurs when Kerberos issues an authentication must be actually observed to be independently verified (a nigh impossible task when Kerberos is stateless).

From there, said Crabtree, the maintenance of an external state mutes the "noisiness" across large enterprise networks, allowing Qomplx to independently identify true signatures and ensure that authentication has been properly issued.

"It's really arcane and it's really low level," said Crabtree. "Except if you do it, you are able to detect the most devastating [attacks].

Crabtree reports that Qomplx's solution has been in production for over a year and a half now -- leading to a rebranding of the company. Originally named Fractal Industries, the company focused on its offering of a big-data analytics streaming platform. Under this new banner of Qomplx, the company secured Series A funding in July.

"We didn't [originally] want to build the Kerberos solution as a business," said Crabtree. "[But] if you can't secure authentication, you can't secure the enterprise."

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—Joe Stanganelli is managing director at research and consulting firm Blackwood King LC. In addition to being an attorney and consultant, he has spent several years analyzing and writing about business and technology trends. Follow him on Twitter at @JoeStanganelli.