Apple will fix a flaw that a security firm said may have left more than half a billion iPhones vulnerable to hackers.

The bug was discovered by Zuk Avraham, chief executive of San Francisco-based mobile security forensics company ZecOps, while investigating a sophisticated cyberattack against a client in late 2019. Avraham said he found evidence the vulnerability was exploited in at least six cybersecurity break-ins.

Specifically, ZecOps found a number of remote attacks that were carried through the default Mail application on iOS dating as far back as Jan 2018. ZecOps analyzed these attacks and discovered an exploitable vulnerability affecting Apple’s iPhones and iPads. They detected multiple, yet targeted, attacks leveraging this vulnerability targeting enterprise users, VIPs, and MSSPs, over a prolonged period of time.

The attack’s scope consists of sending a specially crafted email to a victim’s mailbox enabling it to trigger the vulnerability in the context of iOS MobileMail application on iOS 12 or maild on iOS 13. Based on ZecOps Research and Threat Intelligence, these vulnerabilities – in particular, the remote heap overflow – are widely exploited in the wild in targeted attacks by an advanced threat operator(s).

ZecOps is aware of multiple attacks that happened starting from Jan 2018, on iOS 11.2.2. It is likely that the same threat operators are actively abusing these vulnerabilities presently.

Affected versions:

• All tested iOS versions are vulnerable including iOS 13.4.1.
• These these bugs were actively triggered on iOS 11.2.2 and potentially earlier.
• iOS 6 and above are vulnerable. iOS 6 was released in 2012!

The targets included:

• Individuals from a Fortune 500 organization in North America
• An executive from a carrier in Japan
• A VIP from Germany
• MSSPs from Saudi Arabia and Israel
• A Journalist in Europe
• Suspected: An executive from a Swiss enterprise

While ZecOps refrain from attributing these attacks to a specific threat actor, the security firn is aware that at least one ‘hackers-for-hire’ organization is selling exploits using vulnerabilities that leverage email addresses as a main identifier.

The company advises to update as soon as an iOS update is available.

Apple acknowledged that a vulnerability exists in Apple’s software for email on iPhones and iPads, known as the Mail app, and that the company had developed a fix, which will be rolled out in a forthcoming update on millions of devices it has sold globally.