- Proofpoint detailed BlueMoon, an exploit kit chaining two Chromium flaws and one Windows bug
- Four groups, including China‑aligned TA412, used it loudly against NGOs, aerospace, and manufacturing targets
- Exploits were “patch‑gap” zero‑days; all flaws now patched
Four hacking groups, including some tied to the Chinese government, were seen using the exact same exploit kit in a span of a week, suggesting a certain “fear of missing out” among the criminals, experts have warned.
Security researchers Proofpoint have detailed BlueMoon, an exploit kit that leverages three vulnerabilities: two in Chromium, and one in older versions of Windows: Windows 10 (October 2018 Update), Windows Server 2019, Windows 10 2004, WIndows Server 2022, and the initial release of Windows 11.
The kit was first seen being used on August 28 2026, by a threat actor tracked as TA412, a China-aligned state-sponsored threat actor that was observed in the past targeting businesses using Microsoft SharePoint. TA412, also known as Violet Typhoon, used BlueMoon to “repeatedly target a small number of non-governmental organizations (NGOs), mining companies, and physical commodity trading firms in the United States.”
Soon after that, three others were spotted: UNK_LateNight, another China-aligned espionage group which targeted multiple US aerospace companies, UNK_DoubleCheck, a group going after a Vietnamese manufacturing entity, and UNK_QuietRacket, a threat actor taking aim at organizations across Singapore and Indonesia.
What all of these groups have in common is the fact that they did not try particularly hard to hide their activity. This is rather unusual, since a stealthy approach usually guarantees that a vulnerability can be exploited for longer.
Front running the Chromium supply chain train
BlueMoon takes advantage of three flaws, two in Chromium and one in older Windows variants. The Chromium vulnerabilities were found in V8, the JavaScript engine that the browsers use to allow applications to run efficiently. The first one is a “type confusion bug”, tracked as CVE-2026-85046, and assigned a severity score of 8.8/10 (high). The latter is a “sandbox escape” flaw, for which Google did not assign a CVE or a severity score.
The Windows bug, on the other hand, is tracked as CVE-2026-85880, and was given a severity score of 7.8/10 (high). It is described as a “heap-based buffer overflow” vulnerability in Windows Advanced Local Procedure Call, allowing malicious actors who can already execute code inside a low-privilege AppContainer to escape the sandbox and elevate privileges to SYSTEM. No additional user interaction is required.
Proofpoint has a theory as to why the crooks decided to be loud, instead of flying under the radar. Apparently, there is a very short window of opportunity between Google patching a Chromium vulnerability, and it being deployed to a browser such as Edge, or Brave, This window of opportunity also allows crooks to see how Google fixed a flaw, reverse-engineer it, and deploy an exploit before the browser is patched. This would mean that there is no time to be stealthy.
No time to hide
“Both V8 vulnerabilities were ‘patch-gap’ zero-days at the time of the observed activity,” Proofpoint said. “In other words, while they were known vulnerabilities already fixed in public upstream Chromium source code, they remained unpatched in the latest stable releases of Chrome and Chromium-based browsers available to the public. It is likely that the exploit kit developer used these publicly available Chromium patches to weaponize the browser exploit chain.”
Another important factor is Artificial Intelligence. It would seem that AI has made flaw detection significantly faster, reducing the barrier to entry and making threat actors move more loudly.
“A fully weaponized Chrome exploit chain has historically been a high-value, rare capability. BlueMoon was developed, deployed rapidly, and shared across multiple threat actors within days in a manner that had high detection signals. This may reflect a reduced cost and barrier to entry for this class of capability, as AI agents increasingly enable threat actor exploit development,” Proofpoint stressed.
All three flaws have since been patched, so make sure you’re running the latest version of both the OS and the Chromium browser.
Via Ars Technica
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