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Microsoft infographic titled ARTEX at work: behind Storm-0940's attack, showing 2,250-plus tenants reached with app-only sign-ins, 327 accounts across eight organizations affected by password spray, 151,000-plus failed sign-ins, 2,900 attempts per minute and 200-plus sign-ins in under four minutes using four application credentials.
Graphic: Microsoft Threat Intelligence, Figure 1, scale and speed of a subset of Storm-0940's automated ARTEX campaign on downstream tenants, Oct 21, 2026 (fair use).

Threat Intel

Microsoft Says China-Aligned Storm-0940 Was Behind the ConnectWise Cloud Backup Compromise and Used the ARTEX AI Agent Framework to Try More Than 2,250 Microsoft 365 Tenants at 2,900 Sign-In Attempts a Minute

Microsoft tied the ConnectWise supply chain compromise to a China-aligned group that used an open-source agentic AI penetration testing framework to spray passwords, abuse trusted backup app identities and change privileges inside customer tenants, in some cases reaching privileged cloud access in under three hours. The application IDs, IP addresses, user agents and hunting queries defenders need.

Priya Shah, Threat IntelSingapore6 min read

SINGAPORE - Microsoft has put a name to the group behind the ConnectWise cloud backup compromise, and said the intruders handed much of the work to AI agents. In a report published Wednesday evening, Microsoft Threat Intelligence and Microsoft Security Research said a China-state aligned actor it tracks as Storm-0940 used ARTEX, an open-source agentic AI penetration testing framework, to automate attacks on hundreds of organizations starting as early as September 2026.

Microsoft assessed that Storm-0940 was responsible for the recently disclosed ConnectWise supply chain compromise of a multi-tenant application. Several of the group's ARTEX-driven attacks ended with privileged access to an organization's cloud infrastructure, Microsoft said, including multiple cases in which the time from first targeting to privileged access was less than three hours.

A known actor, a faster tool

Storm-0940 has been active since 2021 and has no known industry aliases, according to Microsoft. It has historically broken in through password spraying and exploitation of internet-facing applications, and in cloud environments has kept access by adding credentials to existing OAuth applications, then using them to pull email and other data through Microsoft Graph.

ARTEX supplied the speed. Microsoft described it as a multi-agent system written in Go with a Next.js front end that can use any AI model to run a penetration test from reconnaissance through data exfiltration with little human interaction, storing what it finds in a graph. The targets included aerospace and defense, energy, financial services, government, legal, semiconductor, software and technology companies, as well as think tanks and nonprofits.

"The speed of the activity allows very little time for Defenders to respond to those alerts and remediate the actor's access in a coordinated fashion," Microsoft wrote.

From password spray to trusted apps

Between Oct. 10 and 14, Storm-0940 infrastructure at 144.172.64[.]99 ran an automated cross-tenant password spray against 327 accounts at eight organizations, Microsoft said. Its telemetry logged more than 151,000 failed sign-ins, peaking on Oct. 11 at 2,900 failures a minute with more than 111,000 in a single day. Forty-eight accounts took more than 1,000 failures each, and nearly 98 percent of the responses were lockouts. That spray produced no successful sign-in.

Microsoft Defender XDR detections table from the Microsoft report listing observed activity and alert titles, including Unusual Microsoft Graph activity associated with Compromised ConnectWise Application and Application self-assigned Global Administrator role.
Screenshot: Microsoft Security Blog, Defender XDR detections for the Storm-0940 ConnectWise activity, Oct 21, 2026 (fair use).

Public reports of the ConnectWise compromise began on Oct. 15 with indicators in the same 144.172.64.x range, and ConnectWise's own advisory on Oct. 16 listed an address that matched 144.172.64[.]99 exactly, according to Microsoft. After taking control of the identities of several ConnectWise cloud applications, the agents used the same range to sign in to customer tenants as those apps, exploiting the trust the apps already had. Microsoft said ARTEX attempted sign-ins to more than 2,250 tenants at 2,900 attempts a minute.

In some tenants, the activity moved on to Microsoft Graph reconnaissance, changes to application credentials and changes involving identities, groups and privileged roles. One Defender alert Microsoft lists for this campaign fires when an application assigns itself the Global Administrator role. Microsoft warned that such credential changes can persist as a backdoor after the original compromised application is fixed, and said the presence of an affected app, or even a successful sign-in, does not by itself mean data was accessed or stolen. The company said the activity did not stem from a compromise of, or a vulnerability in, Microsoft systems.

Indicators of compromise table from the Microsoft report listing IP addresses 144.172.64.128, 144.172.64.99 and 144.172.64.60 seen performing sign-ins and Graph API activity, and VPN addresses 187.15.88.186, 187.15.90.217 and 187.15.89.186 seen accessing the Graph API through the compromised apps.
Screenshot: Microsoft Security Blog, indicators of compromise for Storm-0940's use of the ConnectWise apps, Oct 21, 2026 (fair use).

What to hunt and how to contain it

  • Search every Microsoft 365 tenant where ConnectWise apps are or were installed, by application ID rather than display name: 506e08f9-6e9a-4da4-942b-a099a03644ae (ConnectWise Cloud Backup), 24205314-2b89-4e07-a2a4-579e898a5640 (ConnectWise - MS Teams) and 0de14c77-b9b0-4137-9360-34878a929827 (ConnectWise - MS Graph), as listed in Microsoft's hunting queries.
  • Keep the affected app connections disabled until ConnectWise issues restoration instructions, and do not delete the enterprise applications first. Preserve Entra sign-in and audit logs, Purview audit records and Graph telemetry before making irreversible changes.
  • Review service principal sign-ins from at least Oct. 15, and back to Oct. 1 where logs allow, with successful and failed sign-ins examined separately. Do not limit the review to published IP addresses.
  • Look for sign-ins and Graph calls from 144.172.64[.]128, 144.172.64[.]99 and 144.172.64[.]60, the VPN addresses 187.15.88[.]186, 187.15.90[.]217 and 187.15.89[.]186 for Oct. 15 and 16, and the user agents Python-urllib/3.12, python-requests/2.31.0, python-requests/2.34.2, curl/7.88.1 and azure-toolkit/1.0.
  • In Entra audit logs, check for new application or service principal credentials, new owners, app-role assignments, consent grants, privileged role assignments and changes to Conditional Access or authentication methods.
  • Run Microsoft's published queries: OAuthAppInfo to confirm exposure, EntraIdSpnSignInEvents joined with GraphAPIAuditEvents in Defender XDR, and SigninLogs plus MicrosoftGraphActivityLogs in Sentinel, all starting Oct. 13, 2026.
Header of the Microsoft Security Blog report AI-driven, large-scale nation-state campaign using ARTEX enables supply chain compromise, by Microsoft Security Research and Microsoft Threat Intelligence, dated October 21 with a 14 minute read.
Screenshot: Microsoft Security Blog, the Storm-0940 ARTEX report, Oct 21, 2026 (fair use).

Sources:


Priya Shah covers threat intelligence, adversary tradecraft, and supply-chain campaigns for SOCtember from Singapore.

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