A contractor for Target said Thursday it was also a victim of a cyberattack, supporting the retailer's claim that hackers gained entry to its network via a third party.
The contractor, Fazio Mechanical Services of Sharpsburg, Pennsylvania, issued a statement after the business was mentioned in several media reports as the possible weak link that allowed attackers to eventually steal 40 million payment card details.
"Like Target, we are a victim of a sophisticated cyberattack operation," according to a statement attributed to Fazio's president and owner, Ross E. Fazio.
The company specializes in designing and installing supermarket refrigeration systems, according to its website. A spokesman said Fazio provided refrigeration services to Target.
The company revealed it had a "data connection" with Target, which was used for submitting electronic bills, contracts and project management material.
"Target is the only customer for whom we manage these processes on a remote basis," the statement read. "No other customers have been affected by the breach." The company said it did not remotely monitor Target's heating, cooling or refrigeration systems.
In the statement, Fazio said it could not comment on the technical causes of the breach due to the federal law-enforcement investigation, but said its "IT system and security measures are in full compliance with industry practices."
The Target breach has sent a chill through the retail community, with experts from EMC's RSA security unit saying more than three dozen other retailers could be affected by malicious software installed on point-of-sale (POS) devices.
The U.S. Congress held hearings earlier this week exploring the causes of data breaches and whether industry security initiatives such as PCI DSS (Payment Card Industry Data Security Standard) are falling short.
Target said 40 million payment cards were stolen between Nov. 27 and Dec. 15. It later said up to 70 million other personal records were compromised, making the breach one of the largest on record.
It is suspected that hackers found a weak point in Target's network, which allowed them to maneuver to its point-of-sale terminals to install malicious software. The malware installed is known as a "RAM scraper," which records unencrypted payment card details while the information is briefly stored in a POS device's memory.
Security analysts found that hackers stole 11GB of data, which was quietly shifted to other computers within Target's network before it was sent in batches to remote servers, several in the U.S. and at least one in Russia.
After the Target incident was reported, the high-end store Neiman Marcus last month confirmed a breach of up to 1.1 million cards. The arts and crafts chain Michaels and the hotel management company White Lodging Services are also investigating possible intrusions.
Sign up for CIO Asia eNewsletters.