External risk intelligence

Apple WebKit Code Execution Vulnerability

CVE advisoryKnown Exploit

CVE-2021-30663

An integer overflow in Apple's WebKit could allow attackers to execute arbitrary code by directing systems to process crafted web content. This impacts Apple products like iOS, iPadOS, macOS, tvOS, and Safari, posing a business risk through potential unauthorized code execution.

4Halo Surface Signal

Integer Overflow

Apple Safari

before 14.1.114.0 to before 14.5.1before 12.5.311.0 to before 11.3.1before 14.6

External exposure likelihood

Halo Surface Signal score for CVE-2021-30663

This vulnerability affects web browsers and operating systems that rely on web content processing. Web browsers are designed to interact directly with the public internet to render web pages and media, making them highly likely to encounter and process the type of content necessary to trigger this vulnerability during normal, daily usage.

Horizon Alert

Summary of the vulnerability and why it matters

An integer overflow vulnerability was identified in a core component responsible for processing web content. This flaw could allow an attacker to execute arbitrary code by directing an organization's systems to process specifically crafted web material. The potential business impact includes unauthorized code execution on affected systems.

Vulnerable web content processing
Integer overflow weakness
Arbitrary code execution impact

Attack Path

How an attacker could exploit the issue

An integer overflow vulnerability was identified within Apple's WebKit, which is used in Safari and other products. Processing specially crafted web content could permit an attacker to execute arbitrary code. This could impact organizations that use affected Apple products and rely on web browsers to access external resources.

Web content is accessible.
Attacker sends malicious web content.
Trigger results in code execution.

Live Threat

Current exploitation, exposure, and threat context

A vulnerability exists that could allow for the execution of arbitrary code through the processing of specially crafted web content. This could impact organizations that use affected Apple products and Safari. The risk arises from the potential for attackers to leverage this flaw to gain unauthorized access or control over systems.

Attackers with low skill level.
Access to the internet and user interaction.
High business risk and urgency.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

An integer overflow vulnerability has been identified in Apple products, including iOS, iPadOS, macOS, tvOS, and Safari. When processing maliciously crafted web content, this issue could allow for arbitrary code execution. This presents a significant risk to organizations whose employees use affected devices and web browsers for business operations.

Find all affected devices and software.
Restrict access to untrusted web content.
Update systems and monitor for compromise.

Frequently asked questions

What is Apple's WebKit and what is it used for?

Apple's WebKit is a crucial software component that powers Safari and other applications by handling the rendering and processing of web content. It's what allows your devices to display websites, including text, images, and interactive elements, making it fundamental for browsing the internet on Apple products.

How does CVE-2021-30663 allow code execution?

CVE-2021-30663 is an integer overflow vulnerability, a type of weakness where a program tries to store a number larger than its allocated memory space. In this case, processing specially crafted web content can exploit this overflow to execute arbitrary code, meaning an attacker could potentially run their own commands on the affected device.

What are the preconditions for an attacker to exploit this flaw?

An attacker's precondition involves presenting a user with maliciously crafted web content. The vulnerability is not triggered if the web content is not processed, or if the system is already updated to a version that has addressed the integer overflow issue.

Who should be concerned about this CVE based on its access?

Organizations should be concerned if they use affected Apple products, as this vulnerability has an "external" exposure classification. This means it can be triggered over the internet, making systems that browse the web more likely to encounter the conditions needed to exploit this flaw during normal use.

What is the first step to respond to this threat?

The primary and most effective response is to update affected Apple devices and software, including iOS, iPadOS, macOS, tvOS, and Safari, to the versions that have fixed this integer overflow vulnerability, such as iOS 14.5.1 and Safari 14.1.1.

References

Written by Nicholas Merritt

External-surface CVE analysis and Halo Surface Signal prioritization for Halo Threat Intelligence.