As a result of a continuing major attack, more than 100,000 people have been alerted that their personal information is in the hands of cybercriminals.
Among the firms whose employees have been affected by the MoveIt data leak are the BBC, British Airways, Aer Lingus, and Boots.
As the scope of the breach is revealed, more firms are expected to issue employee warnings.
The most important advice in the early phases of an attack like this is addressed at the organizations.
Hackers aren't interested in going after individuals since it takes too much time, and they just care about one thing: getting paid.
"The important message to organizations right now is not to panic, to install the security patch and not to pay the criminals," former National Cyber Security Centre lead Prof Ciaran Martin says.
However, once an organization has been compromised, the hackers have the upper hand. According to a study, UK businesses are the most inclined to pay hacker ransoms. The individuals suspected of being behind the MoveIt hack are notoriously merciless in their extortion methods. The hackers frequently consider their extortion strategies.
"In some previous incidents involving these criminals, victims were not contacted until weeks after the data was stolen - so if you don't hear from them in the coming days, you are not out of the woods," Mandiant Intelligence senior manager Kimberly Goody explains.
"Some prior incidents involving these criminals have seen victims not contacted until weeks after data was stolen - so if you don't hear from them in the coming days, you are not in clear," Mandiant Intelligence senior manager Kimberly Goody says.
As per Mandiant investigation, the organization, which is considered to be based in Russia, will then contact a firm email account and demand payment not to disclose the stolen data online. According to Mandiant analysts, these demands are often in the seven- to eight-figure range, but some have exceeded $35 million (£28 million).
Law enforcement officials all around the world warn businesses not to pay since it feeds the rise of these criminal groups. Individuals are advised not to panic, but rather to remain cautious. If your company refuses to pay the thieves, they are likely to broadcast the data on the dark web or sell it to other hackers. However, there are several processes between that and you losing money.
"There really is an important message not to panic, as it's very unlikely that organizations have been storing data like full bank details which can lead directly to sort of financial harm," Prof Martin told BBC Radio 4's Today programme.
Individual victims may receive a message claiming to be from their company, requesting that they check in and verify their account because "fraudulent activity has occurred."
Experts recommend keeping an eye out for the following:
- official-sounding messages about "resetting passwords", "receiving compensation", "scanning devices" or "missed deliveries"
- emails full of "tech speak", designed to sound more convincing
- being urged to act immediately or within a limited timeframe
The MoveIt breach is certain to worsen as additional organisations find they have been hacked - although data acquired in prior thefts has been published in an isolated section of the dark web, with little impact to individuals, according to experts.
