MoneyGram, a massive international payment services firm, suffered a debilitating cyber attack over the weekend. It recently reported that it’s beginning to bring systems back online.

The attack began on Friday, Sept. 21, and brought down MoneyGram’s services through the weekend. Even by Monday, users still found that they couldn’t use the service. That same day, MoneyGram admitted on X that it had “a cybersecurity issue affecting certain of its systems.”

During this time, it was down for both individual and business use, causing widespread payment problems to its global customer base. By Tuesday, the company posted on X that it had begun restoring its systems.

“Once all systems are fully operational, transactions that are currently pending will be made available to customers. We apologize for any inconvenience and will continue to share relevant updates as available,” MoneyGram wrote.

Despite having a rough timeline, there aren’t many public details about the attack. Companies have a limited time frame to publicly disclose incidents, but they’re allowed to hide certain details that if made public could result in further cyber attacks.

In one of MoneyGram’s posts on X, they write that they’re “proactively taking systems offline which impacted network connectivity.” Taking down systems proactively is an indicator of ransomware and one of the first steps you take to deal with it. Some experts believe that this is the most likely cause of the outage.

Regardless of its cause, taking down a financial firm has rippling effects on its customers.

“Major breaches like this one can have a devastating impact on organizations and their users,” explains Renuka Nadkarni, chief product officer at Aryaka Networks Inc.

“In this case, MoneyGram, the world’s second-largest money transfer company, processes over 120 million transactions annually from tens of millions of users,” Nadkarni added. “With millions of users and transactions at stake, even a few days of downtime can have severe implications, such as financial losses and harm to customer trust and brand reputation.”