Target breach abused network access given to air conditioning firm

But how did hackers reach point-of-sale terminals?

The third-party contractor whose credentials were used to plant malware on Target's point-of-sale systems in November's huge data breach was an air-conditioning contractor that had been granted an unusual level of networks access, researcher Brian Krebs has reported.

According to a source close to the investigation quoted by Krebs, the hackers stole the credentials used by Fabio Mechanical Systems on 15 November 2013, using this to gain remote access to Target's point-of-sale terminals.

The reason suggested for such a wide-ranging level of privileged access is hard to pin down but a second source told Krebs that it might be connected to the remote monitoring of store temperatures.

This raises the issue of why this kind of account would have allowed such extensive access to other parts of the network although it is also possible that the hackers compromised a second resource before reaching the point-of-sale level. At the very least, the unusual activity on the contractor account should have been detected sooner.

If this account is shown to be correct it suggests an incredibly complacent regime of network security. Target and other retail firms caught up in similar attacks have defended themselves from such accusations.

"Target chose to allow a third party access to its network, but failed to properly secure that access. Even if Target had a valid reason for giving the third party access, the retailer should have segmented its network to ensure that they had no access to its payment systems," said Jody Brazil, CTO of security firm FireMon.

"The only really sophisticated component of the attack appears to have been the malware used to intercept and steal payment card data from Target's POS systems. But the attackers would have been unable to install the malware if Target had employed proper network segmentation practices in the first place," he said.

FireMon is right about network segmentation although if a second resource was compromised this might not be the only problem. Furthermore, was the contractor accessing systems remotely using two-factor authentication and if not, why not? This is a requirement of PCI-DSS 1.0/2.0 standard that sets out a mandatory security regime for looking after credit card data but it is also seen as simply good practice in many enterprises.

The Target data breach - which saw up to 110 million encrypted credit card and customer records pilfered from the company in a matter of days - could still serve as an important case study in how retail security can go wrong. Too often in the past, firms have experienced major breaches and the world (including other firms in the sector that might be targeted in the same way) have learned nothing about how the breaches happened.

In comments made to the Senate Judiciary Committee this week, Target CFO John Mulligan expressed that he was "deeply sorry" for the turn of events; it is starting to look as if merely being sorry won't be enough in future.

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