Devious cybercrooks have developed a Trojan that is capable of redirecting calls your bank has made to verify suspicious transactions – straight into the waiting handsets of professional criminal caller services.
The capability comes bundled in a modified configuration of Ice IX, a Trojan developed using the infamous ZeuS cybercrime toolkit. In addition to stealing bank account data from infected machines, these Ice IX configurations are capturing sensitive information on telephone accounts belonging to the victims who happen to be customers of BT, TalkTalk and Sky. US banking customers have also been targeted by the scam.
By gaining control of phone lines, the crooks are able to divert calls from banks querying suspicious transactions to hacker-controlled phone numbers.
Redirecting bank’s post-transaction verification calls to professional criminal caller services gives crooks more chance of abusing stolen card data for longer, maximising their ill-gotten profits in the process.
Security researchers at transaction security firm Trusteer discovered a strain of malware used in the attack that steals a victim’s user ID and password, memorable information/secret question answer, date of birth and account balance from a compromised machine. Victims are then asked to update their phone numbers of record (home, mobile and work) and select the name of their service provider from a drop-down list. Automated dialogue boxes generated by the malware further attempt to trick victims into handing over their telephone account number, private data that is used by phone firms to authorise account modifications such as call forwarding.
Victims are falsely told the sensitive data is required as part of a verification process caused by "a malfunction of the bank’s anti-fraud system with its landline phone service provider".
In reality that data is used by fraudsters to redirect and fob-off post-transaction verification checks by banks, circumventing an important security check in the process. Victims will find it harder to contest disputed transactions as a result of the ploy, designed to give fraudsters and their accomplices more time to bleed cash from compromised accounts.
Amit Klein, CTO of Trusteer, explained, "Fraudsters are increasingly turning to these post-transaction attack methods to hide fraudulent activity from the victim and block email and phone communication from the bank. This allows attackers to circumvent security mechanisms that look for anomalies once transactions have already been executed by the user."
A full write-up of the attack, complete with screen-shots, can be found in a blog post by Trusteer here. ®
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