Apple patched three security flaws in September 2023 after reporting that they may have been actively exploited against iPhones running iOS versions before 16.7. Citizen Lab and Google’s Threat Analysis Group later documented an exploit chain designed to install Cytrox’s Predator spyware on iOS through 16.6.1. Apple’s advisory did not identify a spyware vendor; Citizen Lab attributed the payload to Predator with high confidence.
What were the three iPhone zero-days?
Apple listed the vulnerabilities in its September 21, 2023 security advisory for iOS 17.0.1 and iPadOS 17.0.1. They affected different parts of the operating system, so their reported capabilities were distinct:
| CVE | Component | Impact Apple described |
|---|---|---|
| CVE-2023-41991 | Security, including certificate validation | A malicious app may bypass signature validation. |
| CVE-2023-41992 | Kernel | A local attacker may be able to elevate privileges. |
| CVE-2023-41993 | WebKit | Processing web content may lead to arbitrary code execution. |
Apple said it addressed CVE-2023-41991 with improved certificate validation, and the other two with improved checks. The advisory’s wording on exploitation was cautious: Apple said it was aware of a report that each issue may have been actively exploited
against versions of iOS before 16.7. It did not name an attacker or describe the incidents.
See Apple’s iOS 17.0.1 and iPadOS 17.0.1 security content.
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Were the flaws exploited to install spyware?
Citizen Lab and Google’s Threat Analysis Group obtained an iOS exploit chain designed to install Predator spyware on devices running through iOS 16.6.1. Citizen Lab attributed the payload to Cytrox’s Predator with high confidence. That technical finding provides the spyware context behind the 2023 reports; it should not be mistaken for a vendor attribution made by Apple.
What Citizen Lab documented
Citizen Lab reported that former Egyptian MP Ahmed Eltantawy was targeted from May through September 2023. It described links sent to him over SMS and WhatsApp. The report also said that in August and September his Vodafone Egypt connection was persistently selected for network injection, a technique that can redirect or interfere with traffic on a network connection.
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Citizen Lab separately attributed the network-injection attack to the Egyptian government with high confidence. This is Citizen Lab’s attribution, not a statement from Apple. The documented case concerns a specific target; it does not establish that the campaign indiscriminately affected iPhone users generally.
Read Citizen Lab’s report, “Predator in the Wires”.
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Which Apple updates fixed the vulnerabilities?
The fixes listed in Apple and CERT-EU’s 2023 advisories varied by CVE and platform. These are historical release versions, not recommendations for what to install today.
| Vulnerability | 2023 fixes listed in the consulted advisories |
|---|---|
| CVE-2023-41991 | iOS 17.0.1 and iPadOS 17.0.1; iOS 16.7 and iPadOS 16.7; watchOS 9.6.3 and 10.0.1; macOS Ventura 13.6. |
| CVE-2023-41992 | iOS 17.0.1 and iPadOS 17.0.1; iOS 16.7 and iPadOS 16.7; watchOS 9.6.3 and 10.0.1; macOS Ventura 13.6. |
| CVE-2023-41993 | iOS 17.0.1 and iPadOS 17.0.1; iOS 16.7 and iPadOS 16.7; Safari 16.6.1; macOS Ventura 13.6. |
Apple’s 17.0.1 advisory covered iPhone XS and later, and iPad Pro 12.9-inch (2nd generation and later), iPad Pro 10.5-inch, iPad Pro 11-inch (1st generation and later), iPad Air (3rd generation and later), iPad (6th generation and later), and iPad mini (5th generation and later). Apple’s watch advisories covered Apple Watch Series 4 and later. Safari 16.6.1 was listed for macOS Big Sur and Monterey; CERT-EU also listed macOS Ventura 13.6 as a fix. These device and platform details refer to the 2023 documents.
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For current protection, open Settings > General > Software Update on an iPhone or iPad and install the current update offered for that device. The corresponding setting on Apple Watch is Settings > General > Software Update; on a Mac, use Apple menu > System Settings > General > Software Update. Apple’s current software guidance, rather than the old version numbers in this incident, should determine which release to install.
Additional historical advisories: watchOS 10.0.1, watchOS 9.6.3, Safari 16.6.1, and CERT-EU Security Advisory 2023-069.
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What this incident does—and does not—show
- Apple’s advisory reported possible active exploitation on iOS versions before 16.7; it did not publish attack details or identify a spyware vendor.
- Citizen Lab and Google TAG documented an exploit chain designed to install Predator through iOS 16.6.1, and Citizen Lab made the payload and network-injection attributions described above.
- The public case documents targeting of a named individual and specific delivery methods. It does not establish how many other people, if any, were targeted through this chain.
- The patches named in the advisories were released in 2023. Use Apple’s current Software Update and security guidance for present-day updates.
SecurityWeek’s September 2023 coverage connected Apple’s patch announcement with the Citizen Lab and Google TAG reporting, while distinguishing that reporting from Apple’s own advisory.
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