ConnectWise ScreenConnect Path Traversal (CVE-2024-1708) Added to CISA KEV — Storm-1175 / Medusa Ransomware Active Exploitation

ConnectWise ScreenConnect Path Traversal (CVE-2024-1708) (TL-2026-0436) is a high-severity software vulnerability scored CVSS 8.4, first published 2026-04-30. It is attributed to Storm-1175 (China), references 2 CVEs (CVE-2024-1708, CVE-2024-1709), maps to 20 MITRE ATT&CK techniques (T1003, T1018, T1021), and is covered by 9 detection rules and 19 indicators of compromise.

Key facts for TL-2026-0436

Threat ID
TL-2026-0436
Severity
HIGH
CVSS
8.4
Status
ACTIVE
Category
VULNERABILITY
First published
2026-04-30
Last reviewed
2026-04-30
Attribution
Storm-1175
Nation-state nexus
China
Target sectors
healthcare, education, professional-services, finance, managed-service-providers
Target regions
Australia, United Kingdom, United States
Detection rules
9
Indicators of compromise
19

Malware and tooling in ConnectWise ScreenConnect Path Traversal (CVE-2024-1708)

Malware and tooling: MEDUSA - S1220, AnyDesk, Mesh Agent, Rclone - S1040, SimpleHelp

On April 28, 2026, CISA added CVE-2024-1708, a ConnectWise ScreenConnect path traversal vulnerability (CWE-22, CVSS 8.4), to the Known Exploited Vulnerabilities catalog with an FCEB remediation deadline of May 12, 2026. The flaw affects on-premises ScreenConnect 23.9.7 and prior and is being chained with the paired authentication-bypass CVE-2024-1709 (CVSS 10.0) to achieve unauthenticated remote code execution. Microsoft Threat Intelligence attributes the high-tempo exploitation to Storm-1175, a financially motivated Medusa ransomware affiliate targeting healthcare, education, professional services and finance organizations across Australia, the United Kingdom and the United States.

How ConnectWise ScreenConnect Path Traversal (CVE-2024-1708) works

CVE-2024-1708 is a path traversal vulnerability (CWE-22) in the ConnectWise ScreenConnect web management interface that affects all on-premises versions 23.9.7 and earlier. The flaw resides in how the application validates and constructs file paths when handling extension uploads via the App_Extensions subsystem. By submitting attacker-controlled path segments containing parent-directory references, an authenticated administrator (or an attacker who has obtained admin via the paired bypass) can write arbitrary files outside the intended extensions directory and into web-accessible locations under the ScreenConnect installation tree. When combined with the ability to upload .aspx content, this primitive yields reliable unauthenticated remote code execution under the ScreenConnect service account, which on Windows installations runs with elevated privileges.

In observed in-the-wild operations, CVE-2024-1708 is invariably chained with CVE-2024-1709, an authentication bypass (CWE-288, CVSS 10.0) in the SetupWizard component. CVE-2024-1709 stems from missing access control on the /SetupWizard.aspx endpoint when accessed via a path that includes a trailing path segment (for example /SetupWizard.aspx/anything). On a fully-installed instance this endpoint should reject access, but the routing logic strips or fails to authenticate the supplemental path, returning the initial setup form to anonymous callers. The attacker walks the wizard, creates a brand new local administrator on the ScreenConnect tenant, authenticates with that account, and then leverages the path-traversal primitive in CVE-2024-1708 to drop a web shell or extension that yields code execution. The composite result is full unauthenticated takeover of the ScreenConnect server and any endpoint enrolled into it — every managed device becomes reachable for command execution, file transfer and on-demand remote access.

ConnectWise was notified of both flaws by researchers at Outpost24 (Mick Behrens) on February 13, 2024 and released ScreenConnect 23.9.8 on February 19, 2024 to remediate the chain on the on-premises product line; cloud tenants on screenconnect.com and hostedrmm.com were patched directly by ConnectWise. Within hours of disclosure, Huntress published full technical analysis with screenshots and a working proof-of-concept, and within 48 hours mass exploitation by multiple ransomware affiliates was reported, including Black Basta, BlackCat/ALPHV, LockBit and Cl0p clusters. CVE-2024-1709 was added to the CISA KEV catalog on February 22, 2024.

In April 2026, Microsoft Threat Intelligence published a detailed campaign report titled 'Storm-1175 focuses gaze on vulnerable web-facing assets in high-tempo Medusa ransomware operations'. Microsoft assesses with high confidence that Storm-1175, a financially motivated actor and prolific Medusa Ransomware-as-a-Service affiliate, has industrialized the CVE-2024-1708/1709 chain alongside other web-facing exposures (Fortinet FortiOS, GeoServer, JetBrains TeamCity) as primary entry points. Following exploitation of ScreenConnect, Storm-1175 deploys legitimate remote management tooling — most commonly Mesh Agent, SimpleHelp, and AnyDesk — for redundant persistence, then performs Active Directory reconnaissance, credential dumping via comsvcs.dll-based LSASS dumps, lateral movement using harvested credentials and RDP, and finally double-extortion deployment of Medusa ransomware. Data exfiltration is staged via Rclone to attacker-controlled cloud buckets, with BITSAdmin frequently used to stage tooling. Microsoft observed intrusions impacting healthcare, education, professional services and finance verticals across Australia, the United Kingdom and the United States, with leak-site listings consistent with the campaign timeline.

CISA added CVE-2024-1708 to the KEV catalog on April 28, 2026 — more than two years after disclosure — citing direct evidence of active exploitation surfaced by Microsoft and incident response partners. Federal civilian executive branch agencies are required to remediate by May 12, 2026. Persistent unpatched on-premises ScreenConnect deployments (versions <= 23.9.7) remain trivially exploitable; defenders should treat any internet-exposed ScreenConnect server below 23.9.8 as actively targeted, audit for unauthorized administrator accounts, search App_Extensions and adjacent web roots for unknown .aspx files, and hunt for outbound connections to known Storm-1175 staging infrastructure including 155.133.5.15 and 155.133.5.14.

MITRE ATT&CK techniques used in TL-2026-0436

Credential Access

T1003 OS Credential Dumping

Discovery

T1018 Remote System Discovery; T1082 System Information Discovery; T1087 Account Discovery

Lateral Movement

T1021 Remote Services

Execution

T1059 Command and Scripting Interpreter

Defense Evasion

T1070 Indicator Removal

Command and Control

T1071 Application Layer Protocol; T1105 Ingress Tool Transfer; T1219 Remote Access Tools

Privilege Escalation

T1078 Valid Accounts

Initial Access

T1133 External Remote Services; T1190 Exploit Public-Facing Application

Persistence

T1136 Create Account; T1505 Server Software Component; T1543 Create or Modify System Process

Impact

T1486 Data Encrypted for Impact; T1490 Inhibit System Recovery

Exfiltration

T1567 Exfiltration Over Web Service

defense-impairment

T1685 Disable or Modify Tools

CVEs associated with ConnectWise ScreenConnect Path Traversal (CVE-2024-1708)

CVE-2024-1708, CVE-2024-1709

Timeline of ConnectWise ScreenConnect Path Traversal (CVE-2024-1708)

  • Outpost24 researcher Mick Behrens privately disclosed CVE-2024-1708 path traversal and CVE-2024-1709 authentication bypass to ConnectWise.
  • ConnectWise released ScreenConnect 23.9.8 fixing both vulnerabilities; cloud tenants on screenconnect.com and hostedrmm.com remediated by vendor.
  • Huntress published full technical analysis with reproducible PoC; mass scanning and exploitation began within hours of public details.
  • CISA added CVE-2024-1709 to the Known Exploited Vulnerabilities catalog after confirmed in-the-wild exploitation by multiple ransomware affiliates.
  • Black Basta, BlackCat/ALPHV, LockBit and Cl0p affiliates observed weaponizing the chain to deploy ransomware against unpatched on-premises ScreenConnect servers.
  • CISA, FBI and MS-ISAC published #StopRansomware: Medusa Ransomware joint advisory (AA25-071A) detailing TTPs and impact.
  • Microsoft Threat Intelligence published 'Storm-1175 focuses gaze on vulnerable web-facing assets in high-tempo Medusa ransomware operations', formally attributing renewed CVE-2024-1708/1709 exploitation to Storm-1175 and documenting AU/UK/US victimology across healthcare, education, professional services and finance.
  • CISA added CVE-2024-1708 to the KEV catalog with FCEB remediation deadline of 2026-05-12, formally confirming continued active exploitation more than two years after disclosure.
  • Federal Civilian Executive Branch (FCEB) remediation deadline for CVE-2024-1708 per BOD 22-01.
  • As of 2026-05-29, CVE-2024-1708 (patched in ScreenConnect 23.9.8) remains actively exploited: CISA added it to KEV on 2026-04-28 with a 2026-05-12 FCEB deadline. Microsoft, Dark Reading and others confirm China-linked Storm-1175 is chaining it with CVE-2024-1709 in ongoing high-velocity Medusa ransomware attacks on unpatched on-prem servers.

Sources cited for ConnectWise ScreenConnect Path Traversal (CVE-2024-1708)

Threats related to ConnectWise ScreenConnect Path Traversal (CVE-2024-1708)

Detection coverage for TL-2026-0436

As of 2026-04-30, Threadlinqs Intelligence publishes 9 detection rule(s) for TL-2026-0436 across Splunk SPL, Microsoft KQL and Sigma, covering 19 indicator(s) of compromise. The whole corpus is readable without an account; a free account unlocks full detection query text in Splunk SPL, Microsoft KQL and Sigma; paid tiers add raw indicator values, correlation and the MCP server. Threadlinqs MCP server · View plans.

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