Panda Labs researchers have identified a scammer who is fleecing British oil buyers using a malware-free spin on the classic Nigerian scam.
They say the scammers steal credentials from oil brokers to swindle buyers across Germany, Spain, and across Asia out of cash.
The sting works using a PDF file in the first stage of the phishing attack which when executed grabs broker credentials and ships it off to a remote server. Those details are used to assume the corporate identity of the broker, whose purloined proxy then makes attractive but phoney oil offers to buyers.
"In short, the scam works like this: the scammer contacts a broker or middleman and offers them a large amount of BLCO (Bonny Light Crude Oil), one to two million barrels, at a very competitive price," the Panda Labs team says in a report [PDF] .
"However, it caught our attention that no antivirus engine had been able to detect it (the attack).
"The PDF file is just a self-extracting file. Once run, it creates a folder and extracts six files into it."
It is unknown if the scammer is thick or slick; they may have avoided malware to reduce noise and complicate threat signature creation, or could have simply lacked the skills to write better malcode.
The attack involves a series of legitimate applications that do not trip antivirus systems to collect usernames and passwords from a victim's local mail client and web browser and shipped it off in a text file to remote servers.
The attacks were detected after a staff member at an unnamed petrochemical organisation opened the crafted PDF file contained in the phishing email scam.
Credentials were harvested over six months with some 860 files stored in the scammer's server relating to at least 10 companies.
The research team even identified the attacker through open source intelligence pinning the scam on a transport and logistics operator from the town of Ikeja in Lagos, Nigeria.
The Spanish Civil Guard has been tipped off to the scam and the alleged identity of the criminal.
Further action is unlikely however because affected oil brokers would rather keep their names out of the spotlight.
"If our theory is correct, the information stolen from these companies has not been used against them, but to defraud oil buyers," the researchers say.
"They prefer to keep a low profile, change their credentials and continue to operate just as if nothing had happened." ®