TalkTalk is continuing to confuse experts with its latest assessment of the root cause of a high profile breach on its systems last week, which may have exposed the bank details including bank information of up to four million customers.

The under-fire telco is saying that it has become the victim of a “sequential attack” when in reality it is talking about a SQL injection attack and not a follow-up assault.

The telecommunications firm previously confused security experts by stating that the customers' data may have been compromised via a Distributed Denial of Service (DDoS) attack which had targeted the company's website.

Successful DDoS attacks make sites unavailable to everyone, including attackers, so what the telco must have meant was that the DDoS attack was used as a distraction while a separate line of attack breached its systems and resulted in the exposure of customers’ private information.

Over the weekend the telco said it had been a victim of a “cyber attack on our website not our core systems” as well as saying partial – rather than, as first feared, complete – credit card details were exposed. In follow-up comments Dido Harding, TalkTalk’s chief executive, seemingly referred to a “sequential attack” (FT story here) when she appeared to mean SQL injection attack, for many years one of the most common classes of web security vulnerability.

Wim Remes, manager EMEA strategic services at Rapid7, the firm behind the Metaspolit penetration testing tool, explained. “What TalkTalk (and some news outlets) calls a 'sequential attack' is actually a SQL injection attack (or SQLi as we colloquially call it). This is an attack vector that has been known for more than a decade and it is still found in web applications around the globe. While it is possible for the error that enables such an attack to slip through a well-established application security program, they are fairly easy to prevent with the proper safeguards in place.”

Remes went on to explain the mechanism of SQL injection attacks, which El Reg sometimes likens to a Jedi mind trick, as well as the role the initial DDoS attack might have played in the breach.

“Through SQL injection an attacker can request arbitrary data from the database behind the application,” Remes explained. “It would be prudent to assume that all data kept within the database is now compromised. TalkTalk also mentions seeing a DDoS attack prior to the actual breach. The tactic of inundating an application with traffic to hide the real attack going on at the same time is very common nowadays. By distracting the target, the attacker buys more time to focus on the assets they are really after. Organisations can address this by implementing multi-layer monitoring systems.”

Getting confused between “sequential attack” and a SQL injection attack is an easy enough mistake to make for a firm outside the technology sector. But TalkTalk is a telco so customers are entitled to expect it to have a clearer grasp of standard infosec practices. Coupled with the confusion over the consequences of what a DDoS attack might mean last week, it doesn’t exactly inspire confidence. All is forgivable in the confusion beforehand but what’s far more serious, of course, is the admission that TalkTalk failed to encrypt all user data. ®

The Register has created a timeline of TalkTalk's contradictory comments following on from the initial announcement of a website outage.