The computer virus that hit Saudi Aramco in August is still causing problems in the oil major’s administrative operations around a month after it was first discovered.

Aramco’s email system is understood to be where the problems now lie, which Aramco says is due to additional security measures. A lot of the communication with the company is now having to be done through personal email accounts, according to sources close to the company. The issue is causing delays in payments to contractors and suppliers, and making essential communication with key Aramco officials difficult.

“Some email addresses are working and others are bouncing back,” says an oil industry source based in Saudi Arabia. “We have been told not to attach any documents to any emails and also use private email accounts, phones and fax machines whenever possible. This is making it very difficult to contact some of the more senior officials.”

Another source says that his company has had to deliver hard copies of invoices in some instances, resulting in payments being delayed.

Aramco announced on 10 September that its network was functionally normally. An oil executive based in Saudi Arabia added that all systems were now working, but extra precautions were being taken for safety reasons: “There are some precautionary measures still in place,” he said. “Unless the emails are text only, then [the email] will not get through to the intended recipient.”

He added that no delays have been experienced in its major operational activities as a result of the virus, known as Shamoon. The initial attack on Saudi Aramco’s IT network was carried out in mid-August and affected 30,000 workstations. It prompted Aramco’s chief executive Khalid al-Falih to issue a statement that the company’s oil and gas production activities as well as downstream operations were unaffected. Shortly after Aramco admitted it had been hit by the virus, Qatar’s RasGas said it had been hit by a similar virus, which forced it to shut down its website and email systems.