The company launched an investigation in early May after receiving reports of unusual activity involving payment cards used at some of its stores. While it now has sufficient evidence to confirm an illegal intrusion, the company declined to comment on the breach's scope until the forensics investigation is complete.
Sally Beauty is one of the largest retailers of beauty products in the U.S. and has over 4,500 stores.
In March last year, the company said hackers stole up to 25,000 customer records containing payment card data. According to the company's annual report for 2014, attackers managed to install malware on some of its point-of-sale systems and captured "track 2" card data.
Track 2 refers to one of the data tracks encoded on a card's magnetic stripe. It contains the card's number and expiration date and can be used by criminals to clone it.
"There can be no assurances that we will not suffer another cyber-attack or data security breach in the future and, if we do, whether our physical, technical and procedural safeguards will adequately protect us against such attacks and breaches," the company said in its report.
The compromise of point-of-sale systems with memory-scraping malware has resulted in some of the largest card breaches over the past two years. The technique was used to steal 56 million payment card records from Home Depot last year and 40 million from Target in late 2013.