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ConnectWise ScreenConnect

product · product:connectwise-screenconnect single-source

Coverage
3
first 2026-08-08 → last 2026-10-08
Latest activity
2026-10-08
Huntress: a Power BI-hosted phishing link installs rogue ScreenConnect clients; in one case a script removed…
Peak priority
high
1 high · 2 notable
Targets
public-sector
sectors: public-sector, technology, healthcare
Sources cited
6
5 hosts

Action items (3)

Do-now tasks recorded on the entries about ConnectWise ScreenConnect, newest first. Check the date before acting on an older one.

  • Upgrade every ConnectWise ScreenConnect on-premise client to 26.6.5 now; where an immediate upgrade is blocked by a change window, remove the TransferFiles role permission from every session group in the interim (Administration > Security > Roles); ScreenConnect servers themselves are not affected, only clients.
    2026-09-12CVE-2026-84869
  • Treat any pre-26.6.5 ScreenConnect client that shows a second, unfamiliar RMM tool (UltraViewer, Quick Assist) or an unexplained ScreenConnect connection ID as compromised, not merely vulnerable: reimage rather than patch in place; the worm mechanism means a technician's own session can already have propagated the infection to every host that client actively connected to.
    2026-09-12CVE-2026-84869
  • Alert on ScreenConnect client installation where the relay hostname is not one your organisation operates, the campaign's installers self-register to an attacker relay on install, so the relay identity is the discriminator that survives every cosmetic change to the lure.
    2026-08-08Interactive fake-update modals, cloud-hosted…

Defender insights

What each entry about ConnectWise ScreenConnect tells a defender to do, newest first.

2026-10-08NOTABLEHuntress: a Power BI-hosted phishing link installs rogue ScreenConnect clients; in one case a script removed the first

Exposure · triage · detection

2026-09-12HIGHexploitedConnectWise patches a ScreenConnect flaw Huntress had already watched turn every infected connection into the next one's launch point

Triage

2026-08-08NOTABLEInteractive fake-update modals, cloud-hosted payloads and self-registering RMM installers deployed at guest permission to stay quiet

Triage

Story timeline

  1. 2026-10-08A phishing link on Microsoft's own Power BI domain slips past mail filters and installs rogue ScreenConnect clients, then, in one incident, a script replaces the first remote-management tool with a second
    active-threatsHuntress: a Power BI-hosted phishing link installs rogue ScreenConnect clients; in one case a script removed the first
  2. 2026-09-12CVE-2026-84869, ConnectWise ScreenConnect: a missing file-transfer authorization check lets an active remote session push and auto-run files on the Host, and Huntress traced worm-like exploitation back to 20 August, weeks before any patch existed (CVSS 9.9)
    trending-vulnerabilitiesConnectWise patches a ScreenConnect flaw Huntress had already watched turn every infected connection into the next one's launch point
  3. 2026-08-08A ScreenConnect distribution campaign fronts fake Microsoft Store and App Store update dialogs, and binds each installer to its operator's relay with an embedded key
    active-threatsInteractive fake-update modals, cloud-hosted payloads and self-registering RMM installers deployed at guest permission to stay quiet

Hunting pivots

CVEs (exploited first)
Releases covered
ConnectWise ScreenConnect ×3
ATT&CK techniques (17 across 10 tactics)

17 techniques observed across 3 entries about this entity, derived from entry metadata and body evidence, never asserted without a published entry behind it · pinned to MITRE ATT&CK v20.0 · compare on the matrix · Navigator layer (JSON)

  • Resource DevelopmentAcquire Infrastructure: Web Services
  • Initial AccessDrive-by Compromise · Phishing: Spearphishing Link
  • ExecutionScheduled Task/Job: Scheduled Task · Command and Scripting Interpreter: PowerShell · Command and Scripting Interpreter: Windows Command Shell · User Execution: Malicious File
  • PersistenceScheduled Task/Job: Scheduled Task · Create or Modify System Process: Windows Service
  • Privilege EscalationScheduled Task/Job: Scheduled Task · Create or Modify System Process: Windows Service · Abuse Elevation Control Mechanism: Bypass User Account Control
  • StealthExploitation for Stealth
  • Defense ImpairmentDisable or Modify Tools
  • Lateral MovementLateral Tool Transfer
  • Command and ControlProxy · Web Service: Bidirectional Communication · Ingress Tool Transfer · Remote Access Tools
  • ImpactResource Hijacking

Resource Development TA0042

T1583.006Acquire Infrastructure: Web Services×1

Adversaries may register for web services that can be used during targeting. A variety of popular websites exist for adversaries to register for a web-based service that can be abused during later stages of the adversary lifecycle, such as during Command and Control (Web Service), Exfiltration Over Web Service, or Phishing. Using common services, such as those offered by Google, GitHub, or Twitter, makes it easier for adversaries to hide in expected noise. By utilizing a web service, adversaries can make it difficult to physically tie back operations to them.

Evidence: 2026-08-08/screenconnect-app-store-fake-update-distribution-campaign · ATT&CK page ↗

Initial Access TA0001

T1189Drive-by Compromise×1

Adversaries may gain access to a system through a user visiting a website over the normal course of browsing. Multiple ways of delivering exploit code to a browser exist (i.e., Drive-by Target), including:

Evidence: 2026-08-08/screenconnect-app-store-fake-update-distribution-campaign · ATT&CK page ↗

T1566.002Phishing: Spearphishing Link×1

Adversaries may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · ATT&CK page ↗

Execution TA0002

T1053.005Scheduled Task/Job: Scheduled Task×1

Adversaries may abuse the Windows Task Scheduler to perform task scheduling for initial or recurring execution of malicious code. There are multiple ways to access the Task Scheduler in Windows. The schtasks utility can be run directly on the command line, or the Task Scheduler can be opened through the GUI within the Administrator Tools section of the Control Panel. In some cases, adversaries have used a .NET wrapper for the Windows Task Scheduler, and alternatively, adversaries have used the Windows netapi32 library and Windows Management Instrumentation (WMI) to create a scheduled task. Adversaries may also utilize the Powershell Cmdlet `Invoke-CimMethod`, which leverages WMI class `PS_ScheduledTask` to create a scheduled task via an XML path.

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · ATT&CK page ↗

T1059.001Command and Scripting Interpreter: PowerShell×1

Adversaries may abuse PowerShell commands and scripts for execution. PowerShell is a powerful interactive command-line interface and scripting environment included in the Windows operating system. PowerShell can also be installed on Linux and macOS. Adversaries can use PowerShell to perform a number of actions, including discovery of information and execution of code. Examples include the <code>Start-Process</code> cmdlet which can be used to run an executable and the <code>Invoke-Command</code> cmdlet which runs a command locally or on a remote computer (though administrator permissions are required to use PowerShell to connect to remote systems).

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · ATT&CK page ↗

T1059.003Command and Scripting Interpreter: Windows Command Shell×1

Adversaries may abuse the Windows command shell for execution. The Windows command shell (cmd) is the primary command prompt on Windows systems. The Windows command prompt can be used to control almost any aspect of a system, with various permission levels required for different subsets of commands. The command prompt can be invoked remotely via Remote Services such as SSH.

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · ATT&CK page ↗

T1204.002User Execution: Malicious File×1

An adversary may rely upon a user opening a malicious file in order to gain execution. Users may be subjected to social engineering to get them to open a file that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Attachment. Adversaries may use several types of files that require a user to execute them, including .doc, .pdf, .xls, .rtf, .scr, .exe, .lnk, .pif, .cpl, .reg, and .iso.

Evidence: 2026-08-08/screenconnect-app-store-fake-update-distribution-campaign · ATT&CK page ↗

Persistence TA0003

T1053.005Scheduled Task/Job: Scheduled Task×1

Adversaries may abuse the Windows Task Scheduler to perform task scheduling for initial or recurring execution of malicious code. There are multiple ways to access the Task Scheduler in Windows. The schtasks utility can be run directly on the command line, or the Task Scheduler can be opened through the GUI within the Administrator Tools section of the Control Panel. In some cases, adversaries have used a .NET wrapper for the Windows Task Scheduler, and alternatively, adversaries have used the Windows netapi32 library and Windows Management Instrumentation (WMI) to create a scheduled task. Adversaries may also utilize the Powershell Cmdlet `Invoke-CimMethod`, which leverages WMI class `PS_ScheduledTask` to create a scheduled task via an XML path.

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · ATT&CK page ↗

T1543.003Create or Modify System Process: Windows Service×1

Adversaries may create or modify Windows services to repeatedly execute malicious payloads as part of persistence. When Windows boots up, it starts programs or applications called services that perform background system functions. Windows service configuration information, including the file path to the service's executable or recovery programs/commands, is stored in the Windows Registry.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

Privilege Escalation TA0004

T1053.005Scheduled Task/Job: Scheduled Task×1

Adversaries may abuse the Windows Task Scheduler to perform task scheduling for initial or recurring execution of malicious code. There are multiple ways to access the Task Scheduler in Windows. The schtasks utility can be run directly on the command line, or the Task Scheduler can be opened through the GUI within the Administrator Tools section of the Control Panel. In some cases, adversaries have used a .NET wrapper for the Windows Task Scheduler, and alternatively, adversaries have used the Windows netapi32 library and Windows Management Instrumentation (WMI) to create a scheduled task. Adversaries may also utilize the Powershell Cmdlet `Invoke-CimMethod`, which leverages WMI class `PS_ScheduledTask` to create a scheduled task via an XML path.

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · ATT&CK page ↗

T1543.003Create or Modify System Process: Windows Service×1

Adversaries may create or modify Windows services to repeatedly execute malicious payloads as part of persistence. When Windows boots up, it starts programs or applications called services that perform background system functions. Windows service configuration information, including the file path to the service's executable or recovery programs/commands, is stored in the Windows Registry.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

T1548.002Abuse Elevation Control Mechanism: Bypass User Account Control×1

Adversaries may bypass UAC mechanisms to elevate process privileges on system. Windows User Account Control (UAC) allows a program to elevate its privileges (tracked as integrity levels ranging from low to high) to perform a task under administrator-level permissions, possibly by prompting the user for confirmation. The impact to the user ranges from denying the operation under high enforcement to allowing the user to perform the action if they are in the local administrators group and click through the prompt or allowing them to enter an administrator password to complete the action.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

Stealth TA0005

T1211Exploitation for Stealth×1

Adversaries may exploit vulnerabilities to evade detection by hiding activity, suppressing logging, or operating within trusted or unmonitored components.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

Defense Impairment TA0112

T1685Disable or Modify Tools×1

Adversaries may disable, degrade, or tamper with security tools or applications (e.g., endpoint detection and response (EDR) tools, intrusion detection systems (IDS), antivirus, logging agents, sensors, etc.) to impair or reduce visibility of defensive capabilities. This may include stopping specific services, killing processes, modifying or deleting tool configuration files and Registry keys, or preventing tools from updating. This may also include impairing defenses more broadly by disrupting preventative, detection, and response mechanisms across host, network, and cloud environments.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

Lateral Movement TA0008

T1570Lateral Tool Transfer×1

Adversaries may transfer tools or other files between systems in a compromised environment. Once brought into the victim environment (i.e., Ingress Tool Transfer) files may then be copied from one system to another to stage adversary tools or other files over the course of an operation.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

Command and Control TA0011

T1090Proxy×1

Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure. Many tools exist that enable traffic redirection through proxies or port redirection, including HTRAN, ZXProxy, and ZXPortMap. Adversaries use these types of proxies to manage command and control communications, reduce the number of simultaneous outbound network connections, provide resiliency in the face of connection loss, or to ride over existing trusted communications paths between victims to avoid suspicion. Adversaries may chain together multiple proxies to further disguise the source of malicious traffic.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

T1102.002Web Service: Bidirectional Communication×1

Adversaries may use an existing, legitimate external Web service as a means for sending commands to and receiving output from a compromised system over the Web service channel. Compromised systems may leverage popular websites and social media to host command and control (C2) instructions. Those infected systems can then send the output from those commands back over that Web service channel. The return traffic may occur in a variety of ways, depending on the Web service being utilized. For example, the return traffic may take the form of the compromised system posting a comment on a forum, issuing a pull request to development project, updating a document hosted on a Web service, or by sending a Tweet.

Evidence: 2026-08-08/screenconnect-app-store-fake-update-distribution-campaign · ATT&CK page ↗

T1105Ingress Tool Transfer×2

Adversaries may transfer tools or other files from an external system into a compromised environment. Tools or files may be copied from an external adversary-controlled system to the victim network through the command and control channel or through alternate protocols such as ftp. Once present, adversaries may also transfer/spread tools between victim devices within a compromised environment (i.e. Lateral Tool Transfer).

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

T1219Remote Access Tools×3

An adversary may use legitimate remote access tools to establish an interactive command and control channel within a network. Remote access tools create a session between two trusted hosts through a graphical interface, a command line interaction, a protocol tunnel via development or management software, or hardware-level access such as KVM (Keyboard, Video, Mouse) over IP solutions. Desktop support software (usually graphical interface) and remote management software (typically command line interface) allow a user to control a computer remotely as if they are a local user inheriting the user or software permissions. This software is commonly used for troubleshooting, software installation, and system management. Adversaries may similarly abuse response features included in EDR and other defensive tools that enable remote access.

Evidence: 2026-10-08/power-bi-dashboard-phishing-rogue-screenconnect-clients · 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · 2026-08-08/screenconnect-app-store-fake-update-distribution-campaign · ATT&CK page ↗

Impact TA0040

T1496Resource Hijacking×1

Adversaries may leverage the resources of co-opted systems to complete resource-intensive tasks, which may impact system and/or hosted service availability.

Evidence: 2026-09-12/cve-2026-84869-connectwise-screenconnect-worm-file-transfer · ATT&CK page ↗

Entries about ConnectWise ScreenConnect (3)

2026-10-08 · view entry permalink →

NOTABLENATOB2

A phishing link on Microsoft's own Power BI domain slips past mail filters and installs rogue ScreenConnect clients, then, in one incident, a script replaces the first remote-management tool with a second

Huntress describes a phishing campaign it has seen since 2026-09-10 in which an Outlook email carries a link that leads to a fake reference document on a legitimate Power BI domain (Huntress, 2026-10-07). Huntress notes that threat actors have previously abused Power BI in this way, building a real dashboard under an account of their own (usually compromised or throwaway), embedding a malicious link and setting its sharing to public, and that because the link points to Microsoft's real domain it passes Microsoft 365 mail filters and other gateways that trust that domain; it does not say how this campaign's page was set up (Huntress, 2026-10-07). A "Download Reference" button opens a new tab on an attacker domain that fingerprints the visitor (operating system, browser, automation indicators, cloud-provider cookies), reports victims to a Telegram bot and redirects visitors who fail its checks; after a delay a script clicks a hidden download link for a ScreenConnect installer (Huntress, 2026-10-07).

The installer deploys a first rogue ScreenConnect client, which establishes a second one pointed at different infrastructure (Huntress, 2026-10-07). In one incident the first client ran a command-shell script that launched a PowerShell script from the temp directory; that script downloaded and ran the installer for the second client and uninstalled the first, in a likely effort to evade detection, and a scheduled task re-ran it every two minutes before the attack was shut down (Huntress, 2026-10-07). After deployment the clients also ran a tool Huntress assessed as designed to hide the attacker's activity from the user and security software (Huntress, 2026-10-07). A handful of endpoints were hit from 2026-09-10, and the configuration of one of the rogue clients also appeared on 22 other endpoints in separate incidents (Huntress, 2026-10-07). The original email and lure wording are unknown.

Triage: ScreenConnect is legitimate where the organisation runs it; the discriminators are an instance that is not the organisation's own and an installer that arrived through a browser download from a web page rather than through IT's deployment tooling (Huntress, 2026-10-07).

Because the link points to Microsoft's real Power BI domain, it skirts through Microsoft 365 mail filters and other security gateways that trust this domain.

the PowerShell script also resulted in the uninstallation of the first ScreenConnect instance, in a likely effort to evade detection

Huntress 2026-10-07
threat08 Oct 04:53Zsingle-sourceOpen finding →
Sources: Huntress

2026-09-12 · view entry permalink →

HIGHCVE-2026-84869exploitedNATOA1

CVE-2026-84869, ConnectWise ScreenConnect: a missing file-transfer authorization check lets an active remote session push and auto-run files on the Host, and Huntress traced worm-like exploitation back to 20 August, weeks before any patch existed (CVSS 9.9)

ConnectWise's own disclosure describes a client-side condition in ScreenConnect Support and Access sessions where file-transfer actions could be processed through an active remote session "without proper authorization or Host confirmation," letting files be transferred to and executed on the Host system, including through elevated execution paths (ConnectWise, 2026-09-08). ScreenConnect servers are not affected, only client versions before 26.6.5, the release that fixes CVE-2026-84869 (CWE-862 Missing Authorization, CWE-269 Improper Privilege Management, CVSS 9.9).

Huntress had been tracking the exploitation for two and a half weeks before any advisory existed. Starting 20 August 2026, its SOC found rogue ScreenConnect clients deployed via social engineering (a fake tech-support Quick Assist session in one case, a phishing-driven MSI in another) that immediately spawned four chained VBScript stagers via wscript.exe. The stagers profile the host (existing ScreenConnect install, installed security-product names, available RAM to rule out a sandbox), then pull an AES-encrypted payload bundle keyed to that profile from Dropbox. Depending on the profile, the final PowerShell stage installs a ScreenConnect backdoor client concealed as a hidden Windows service, its registry Uninstall entry removed and a restrictive service security descriptor applied, builds a UAC-bypass helper via a hijacked ms-settings: protocol handler routed through ComputerDefaults.exe, sets AmsiUtils.amsiInitFailed = true to blind AMSI, adds all of C:\Users as a Defender exclusion, and disables Defender reporting, notifications and Hypervisor-Protected Code Integrity, the last of these via a vulnerable WinRing0 kernel driver dropped alongside the payload (Huntress, 2026-09-03). The broadest observed variant then drops a wstunnel tunneling tool disguised as Themes.exe and an XMRig cryptominer disguised as SearchIndex.exe.

The installed backdoor client is what turns the bug into a worm: it continuously inspects ScreenConnect's own connection-status collection for newly established Host sessions and, on each new connection, packages the same four VBScript stagers into a ScreenConnect file-transfer message flagged to auto-run, the exact abuse path CVE-2026-84869 patches. A technician's ScreenConnect client that has been infected this way silently re-infects every subsequent host it connects to, independent of the original social-engineering vector (Huntress, 2026-09-03). No named threat-actor cluster is attributed by any source; CISA added the CVE to its Known Exploited Vulnerabilities catalog on 2026-09-11 with a three-day remediation deadline (CISA KEV, catalogue version 2026.09.11).

A condition in the ScreenConnect client may allow files to be transferred and executed through an active remote session without authorization or Host confirmation in certain circumstances. ScreenConnect servers are not impacted.

ConnectWise (vendor disclosure) 2026-09-08

This creates a worm-like behavior: propagating infections over new ScreenConnect connections. Connecting to an infected ScreenConnect client can cause the server-side Host system to receive and execute the same four-stage VBScript chain.

In late August, our Security Operations Center (SOC) sent out three critical incident reports for what looked like malicious ScreenConnect installation and unexpected process execution.

Huntress 2026-09-03
vulnerability12 Sep 04:09Zmulti-sourceOpen finding →

2026-08-08 · view entry permalink →

NOTABLENATOB2

A ScreenConnect distribution campaign fronts fake Microsoft Store and App Store update dialogs, and binds each installer to its operator's relay with an embedded key

LevelBlue's SpiderLabs OpsCTI team is tracking a ScreenConnect distribution campaign whose lure has moved past the static fake-update page. Instead, it "recreates convincing software update and installation alerts by impersonating the Microsoft Store and Apple App Store while reproducing the look and behavior of trusted applications through dynamic modal dialogs and other interactive web elements", also imitating the Google Meet pre-join screen, with progress bars and camera and microphone permission prompts that behave the way the real dialogs do (LevelBlue SpiderLabs, 2026-08-07).

The installation chain is a batch script into PowerShell into an MSI installed silently through msiexec.exe /quiet with UAC elevation. The operational detail worth carrying is what happens next: "Because each installer is cryptographically bound to its corresponding relay server through the embedded public key, it automatically registers with the attacker's ScreenConnect instance once installed" (LevelBlue SpiderLabs, 2026-08-07). The agent is deployed at guest-level permission rather than full administrative rights, which keeps its footprint small and its behaviour closer to a legitimate support install.

The delivery infrastructure is built to survive the loss of any single component: thousands of near-identical phishing-framework deployments, payloads hosted on legitimate cloud object storage (AWS S3, Cloudflare R2), anti-automation gating through honeypot form fields, artificial delays and User-Agent filtering to Windows desktop clients only, and full victim fingerprinting (address, geolocation, ISP, browser, timezone, screen resolution) before an installer is served at all. Successful infections notify the operator in real time through the Telegram Bot API. LevelBlue assesses the supporting scripts as AI-assisted on the basis of unusually verbose documentation-style inline comments and emoji markers (LevelBlue SpiderLabs, 2026-08-07).

Triage: the benign lookalike is a real support session, and it is common. The discriminators the cited mechanics support, in order of strength: the relay hostname the client registers to; installation at guest-level permission with no corresponding helpdesk ticket; and the process lineage, a browser spawning a batch script or PowerShell that calls msiexec.exe /quiet, which is not how a user or an administrator installs remote-support software deliberately. The fingerprinting gate also means an analyst re-visiting the lure URL from a sandbox or a non-Windows client will usually be served a decoy rather than the installer, so failure to reproduce the payload is not evidence the report is wrong.

impersonating the Microsoft Store and Apple App Store

Because each installer is cryptographically bound to its corresponding relay server through the embedded public key, it automatically registers with the attacker's ScreenConnect instance once installed.

LevelBlue SpiderLabs 2026-08-07
threat08 Aug 05:19Zsingle-sourceOpen finding →

Co-occurring entities

Derived: referenced by the same focused operational entries (weekly summaries and report roundups don't count); ×N counts the shared entries.

Where this entity is cited

  • Threats2
  • Vulns1

Source distribution

  • huntress.com2 (33%)
  • cisa.gov1 (17%)
  • github.com1 (17%)
  • levelblue.com1 (17%)
  • securityweek.com1 (17%)