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SonicWall SonicOS improper access control (mgmt + SSLVPN, Gen 5/6/7), Akira/Fog ransomware on-ramp

cve · CVE-2024-40766 single-source-national-cert

Coverage
2
first 2026-06-23 → last 2026-10-21
Latest activity
2026-10-21
Joint advisory on SafePay: VPN credentials and five old edge and backup flaws in, backup NAS wiped before…
Peak priority
high
1 high · 1 notable
Targets
public-sector
sectors: public-sector, healthcare, education · regions: europe, switzerland
Sources cited
10
6 hosts

Action items (1)

Do-now tasks recorded on the entries about CVE-2024-40766, newest first. Check the date before acting on an older one.

  • Run the SonicWall post-patch hardening pass on any Gen 5/6/7 device patched for CVE-2024-40766: rotate all SonicWall account passwords, enforce SSLVPN MFA (including LDAP default-group-derived users), remove the LDAP Default Group's implicit VPN grant, and restrict the Virtual Office Portal to internal networks. Patching alone did not close the path Akira/Fog use.
    2026-06-23CVE-2024-40766

Defender insights

What each entry about CVE-2024-40766 tells a defender to do, newest first.

2026-10-21NOTABLEexploitedJoint advisory on SafePay: VPN credentials and five old edge and backup flaws in, backup NAS wiped before encryption

Exposure · triage · detection

2026-06-23HIGHexploitedSonicWall CVE-2024-40766: why patched firewalls keep falling to Akira and Fog

Detection

Story timeline

  1. 2026-10-21AA26-293A: FBI, CISA and German and UK law enforcement describe SafePay ransomware, which enters through VPN credentials and five edge-device and backup-server flaws and factory-resets backup NAS devices before encrypting
    active-threatsJoint advisory on SafePay: VPN credentials and five old edge and backup flaws in, backup NAS wiped before encryption
  2. 2026-06-23SonicWall CVE-2024-40766: why patched firewalls keep falling to Akira and Fog
    deep-dive
ATT&CK techniques (25 across 12 tactics)

25 techniques observed across 2 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)

  • Initial AccessValid Accounts · Valid Accounts: Domain Accounts · External Remote Services · Exploit Public-Facing Application
  • ExecutionCommand and Scripting Interpreter: PowerShell · Command and Scripting Interpreter: Windows Command Shell · System Services: Service Execution
  • PersistenceValid Accounts · Valid Accounts: Domain Accounts · Account Manipulation · External Remote Services · Create Account
  • Privilege EscalationValid Accounts · Valid Accounts: Domain Accounts · Account Manipulation · Access Token Manipulation: Token Impersonation/Theft · Abuse Elevation Control Mechanism: Bypass User Account Control
  • StealthObfuscated Files or Information: Software Packing · Indicator Removal: File Deletion · Valid Accounts · Valid Accounts: Domain Accounts · Access Token Manipulation: Token Impersonation/Theft · System Binary Proxy Execution
  • Defense ImpairmentDisable or Modify Tools
  • Credential AccessBrute Force
  • Lateral MovementRemote Services: Remote Desktop Protocol · Remote Services: SMB/Windows Admin Shares · Remote Services: Windows Remote Management
  • CollectionArchive Collected Data: Archive via Utility
  • Command and ControlRemote Access Tools
  • ExfiltrationExfiltration Over Alternative Protocol · Exfiltration Over Web Service
  • ImpactData Encrypted for Impact · Inhibit System Recovery

Initial Access TA0001

T1078Valid Accounts×2

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop. Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1078.002Valid Accounts: Domain Accounts×1

Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.

Evidence: 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1133External Remote Services×2

Adversaries may leverage external-facing remote services to initially access and/or persist within a network. Remote services such as VPNs, Citrix, and other access mechanisms allow users to connect to internal enterprise network resources from external locations. There are often remote service gateways that manage connections and credential authentication for these services. Services such as Windows Remote Management and VNC can also be used externally.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1190Exploit Public-Facing Application×1

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network. The weakness in the system can be a software bug, a temporary glitch, or a misconfiguration.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Execution TA0002

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: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 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: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1569.002System Services: Service Execution×1

Adversaries may abuse the Windows service control manager to execute malicious commands or payloads. The Windows service control manager (<code>services.exe</code>) is an interface to manage and manipulate services. The service control manager is accessible to users via GUI components as well as system utilities such as <code>sc.exe</code> and Net.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Persistence TA0003

T1078Valid Accounts×2

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop. Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1078.002Valid Accounts: Domain Accounts×1

Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.

Evidence: 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1098Account Manipulation×1

Adversaries may manipulate accounts to maintain and/or elevate access to victim systems. Account manipulation may consist of any action that preserves or modifies adversary access to a compromised account, such as modifying credentials or permission groups. These actions could also include account activity designed to subvert security policies, such as performing iterative password updates to bypass password duration policies and preserve the life of compromised credentials.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1133External Remote Services×2

Adversaries may leverage external-facing remote services to initially access and/or persist within a network. Remote services such as VPNs, Citrix, and other access mechanisms allow users to connect to internal enterprise network resources from external locations. There are often remote service gateways that manage connections and credential authentication for these services. Services such as Windows Remote Management and VNC can also be used externally.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1136Create Account×1

Adversaries may create an account to maintain access to victim systems. With a sufficient level of access, creating such accounts may be used to establish secondary credentialed access that do not require persistent remote access tools to be deployed on the system.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Privilege Escalation TA0004

T1078Valid Accounts×2

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop. Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1078.002Valid Accounts: Domain Accounts×1

Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.

Evidence: 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1098Account Manipulation×1

Adversaries may manipulate accounts to maintain and/or elevate access to victim systems. Account manipulation may consist of any action that preserves or modifies adversary access to a compromised account, such as modifying credentials or permission groups. These actions could also include account activity designed to subvert security policies, such as performing iterative password updates to bypass password duration policies and preserve the life of compromised credentials.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1134.001Access Token Manipulation: Token Impersonation/Theft×1

Adversaries may duplicate then impersonate another user's existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user's security context, or with `SetThreadToken` to assign the impersonated token to a thread.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 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: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Stealth TA0005

T1027.002Obfuscated Files or Information: Software Packing×1

Adversaries may perform software packing or virtual machine software protection to conceal their code. Software packing is a method of compressing or encrypting an executable. Packing an executable changes the file signature in an attempt to avoid signature-based detection. Most decompression techniques decompress the executable code in memory. Virtual machine software protection translates an executable's original code into a special format that only a special virtual machine can run. A virtual machine is then called to run this code.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1070.004Indicator Removal: File Deletion×1

Adversaries may delete files left behind by the actions of their intrusion activity. Malware, tools, or other non-native files dropped or created on a system by an adversary (ex: Ingress Tool Transfer) may leave traces to indicate to what was done within a network and how. Removal of these files can occur during an intrusion, or as part of a post-intrusion process to minimize the adversary's footprint.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1078Valid Accounts×2

Adversaries may obtain and abuse credentials of existing accounts as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Compromised credentials may be used to bypass access controls placed on various resources on systems within the network and may even be used for persistent access to remote systems and externally available services, such as VPNs, Outlook Web Access, network devices, and remote desktop. Compromised credentials may also grant an adversary increased privilege to specific systems or access to restricted areas of the network. Adversaries may choose not to use malware or tools in conjunction with the legitimate access those credentials provide to make it harder to detect their presence.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1078.002Valid Accounts: Domain Accounts×1

Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.

Evidence: 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1134.001Access Token Manipulation: Token Impersonation/Theft×1

Adversaries may duplicate then impersonate another user's existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user's security context, or with `SetThreadToken` to assign the impersonated token to a thread.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1218System Binary Proxy Execution×1

Adversaries may bypass process and/or signature-based defenses by proxying execution of malicious content with signed, or otherwise trusted, binaries. Binaries used in this technique are often Microsoft-signed files, indicating that they have been either downloaded from Microsoft or are already native in the operating system. Binaries signed with trusted digital certificates can typically execute on Windows systems protected by digital signature validation. Several Microsoft signed binaries that are default on Windows installations can be used to proxy execution of other files or commands.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 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: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Credential Access TA0006

T1110Brute Force×1

Adversaries may use brute force techniques to gain access to accounts when passwords are unknown or when password hashes are obtained. Without knowledge of the password for an account or set of accounts, an adversary may systematically guess the password using a repetitive or iterative mechanism. Brute forcing passwords can take place via interaction with a service that will check the validity of those credentials or offline against previously acquired credential data, such as password hashes.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Lateral Movement TA0008

T1021.001Remote Services: Remote Desktop Protocol×1

Adversaries may use Valid Accounts to log into a computer using the Remote Desktop Protocol (RDP). The adversary may then perform actions as the logged-on user.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1021.002Remote Services: SMB/Windows Admin Shares×1

Adversaries may use Valid Accounts to interact with a remote network share using Server Message Block (SMB). The adversary may then perform actions as the logged-on user.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1021.006Remote Services: Windows Remote Management×1

Adversaries may use Valid Accounts to interact with remote systems using Windows Remote Management (WinRM). The adversary may then perform actions as the logged-on user.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Collection TA0009

T1560.001Archive Collected Data: Archive via Utility×1

Adversaries may use utilities to compress and/or encrypt collected data prior to exfiltration. Many utilities include functionalities to compress, encrypt, or otherwise package data into a format that is easier/more secure to transport.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Command and Control TA0011

T1219Remote Access Tools×1

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: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Exfiltration TA0010

T1048Exfiltration Over Alternative Protocol×1

Adversaries may steal data by exfiltrating it over a different protocol than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

T1567Exfiltration Over Web Service×1

Adversaries may use an existing, legitimate external Web service to exfiltrate data rather than their primary command and control channel. Popular Web services acting as an exfiltration mechanism may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to compromise. Firewall rules may also already exist to permit traffic to these services.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Impact TA0040

T1486Data Encrypted for Impact×2

Adversaries may encrypt data on target systems or on large numbers of systems in a network to interrupt availability to system and network resources. They can attempt to render stored data inaccessible by encrypting files or data on local and remote drives and withholding access to a decryption key. This may be done in order to extract monetary compensation from a victim in exchange for decryption or a decryption key (ransomware) or to render data permanently inaccessible in cases where the key is not saved or transmitted.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · 2026-06-23/sonicwall-cve-2024-40766-why-patched-firewalls-keep-falling · ATT&CK page ↗

T1490Inhibit System Recovery×1

Adversaries may delete or remove built-in data and turn off services designed to aid in the recovery of a corrupted system to prevent recovery. This may deny access to available backups and recovery options.

Evidence: 2026-10-21/aa26-293a-safepay-ransomware-edge-flaws-backup-nas-reset · ATT&CK page ↗

Entries about SonicWall SonicOS improper access control (mgmt + SSLVPN, Gen 5/6/7), Akira/Fog ransomware on-ramp (2)

2026-10-21 · view entry permalink →

NOTABLECVE-2020-3259 +4exploitedNATOA2

AA26-293A: FBI, CISA and German and UK law enforcement describe SafePay ransomware, which enters through VPN credentials and five edge-device and backup-server flaws and factory-resets backup NAS devices before encrypting

CISA, the FBI, the US Secret Service, Germany's Landeskriminalamt Rheinland-Pfalz and UK law enforcement published advisory AA26-293A on 2026-10-20, drawing on investigations as recently as August 2026; they say SafePay has affected businesses and critical infrastructure in North America, South America, Europe and Australia since August 2024, was among the most active ransomware groups in 2026 and has impacted at least 600 separate victims (CISA et al., 2026-10-20). Initial access is exposed credentials, brute force password attacks and VPN access, with the actors using Mullvad VPN addresses and phished account profiles to reach victim networks and exploit CVE-2020-3259 and CVE-2023-20269 on edge devices, and automated scripts exploiting CVE-2023-27532, CVE-2024-40711 and CVE-2024-40766 on internet-exposed systems (CISA et al., 2026-10-20). CISA's catalog names them as Cisco ASA and Firepower Threat Defense (the first two), Veeam Backup & Replication (the next two) and SonicWall SonicOS flaws (CISA KEV catalog, 2026-10-20).

Once inside, the actors take administrative rights on existing accounts or create new ones, run commands remotely with PsExec and WinRM, enumerate network shares with ShareFinder.ps1 and SharpShares.exe, disable security software, bypass User Account Control, then move over RDP and remote-management tools (CISA et al., 2026-10-20). They compress data with 7-Zip or WinRAR and exfiltrate it with WinSCP, RClone, FileZilla or OneDrive, and sometimes install AnyDesk or TeamViewer (CISA et al., 2026-10-20). Before encrypting they halt the Volume Shadow Copy Service and reset network-attached storage that holds backup data to factory settings; encryption then appends .SafePay (CISA et al., 2026-10-20).

Triage: 7-Zip, WinRAR, RClone, FileZilla, AnyDesk, TeamViewer, PsExec and WinRM are everyday administrative tools, and the advisory warns against calling them malicious without evidence of actor use (CISA et al., 2026-10-20); a shadow-copy service stop or a factory reset of backup storage that follows them is the discriminating step.

The SafePay threat actors have impacted at least 600 separate victims from multiple critical infrastructure sectors.

SafePay ransomware was among the most active ransomware groups in 2026.

SafePay threat actors halt the Volume Shadow Copy Service and reset Network Attached Storage containing victim backup data to initial factory settings to inhibit system recovery attempts

CISA, FBI, USSS, LKA Rheinland-Pfalz, UK NCA (AA26-293A) 2026-10-20

Builds on: Inside IT: SafePay published about 30 GB from Manno, social-assistance files with AHV numbers… · SonicWall CVE-2024-40766: why patched firewalls keep falling to Akira and Fog

threat21 Oct 03:42Zsingle-source · national CERTOpen finding →

2026-06-23 · view entry permalink →

HIGHCVE-2024-40766exploited

SonicWall CVE-2024-40766: why patched firewalls keep falling to Akira and Fog

Background. CVE-2024-40766 is an improper-access-control flaw (vendor advisory SNWLID-2024-0015, CVSS 9.3) in the SonicOS management interface and SSLVPN across Gen 5/6/7 SonicWall firewalls, with patches available since August 2024. Through late 2025 it became one of the most reliable ransomware on-ramps in the field: Arctic Wolf documented an aggressive Akira campaign that used compromised SSLVPN credentials tied to the CVE to reach full ransomware deployment in an hour or less (Arctic Wolf, 2025-09-26). Nearly a year after the patch, the same device class keeps appearing in Akira and Fog intrusions, which is the puzzle a fresh SANS Internet Storm Center diary (2026-06-23) sets out to explain (SANS ISC, 2026-06-23).

The mechanism is post-patch residue, not an unpatched bug. The SANS ISC analysis makes the operationally important point explicit: organisations apply the firmware update but never complete the hardening that the update assumes, so the access paths the intrusions ride survive the patch (SANS ISC, 2026-06-23). SANS ISC further notes that on Gen 6 devices the firmware update alone is insufficient: a related SSLVPN MFA-bypass weakness (CVE-2024-12802) needs manual LDAP reconfiguration to close. Four residual misconfigurations recur:

  • Stale local accounts created during initial device setup that were never removed and whose passwords were never rotated, including after the CVE-2024-40766 patch, even though the flaw's impact is precisely unauthorised access to such accounts.
  • LDAP "Default Group" with implicit SSLVPN access, which silently grants VPN rights to potentially hundreds of Active Directory accounts without the administrator realising the membership scope.
  • Unenforced or misconfigured MFA on the SSLVPN portal, so a single valid credential is sufficient.
  • A publicly reachable Virtual Office Portal (the SSLVPN self-service / MFA-enrolment page), which exposes credential-stuffing and self-enrolment attack surface to the internet.

Kill chain. The pattern maps cleanly: initial access via valid SSLVPN credentials (T1133 External Remote Services, T1133) using stolen or stale T1078 Valid Accounts (T1078), frequently T1078.002 Domain Accounts (T1078.002) when the LDAP default-group grant pulls AD identities into the VPN scope, followed by rapid lateral movement and Akira/Fog encryption (T1486 Data Encrypted for Impact, T1486). Arctic Wolf's "deploys ransomware in an hour or less" framing is the operational tempo to plan against: there is little dwell time in which to react once the VPN foothold is established.

Why it matters to us. SonicWall is a common branch-office and SMB perimeter firewall across Swiss cantonal/communal IT, healthcare and education networks, the exact mid-market public-sector estate this brief serves, and the kind of environment where a device was patched in 2024, ticket closed, and never revisited. The defender lesson generalises beyond SonicWall: applying a firewall patch for an access-control CVE does not rotate the credentials the CVE may already have exposed, nor does it close the misconfigurations that let a single credential become VPN access.

Detection concepts (no IOCs). Review SonicOS SSLVPN authentication logs (the SSLVPN auth events; SonicOS exposes these via syslog) for logons from stale/rarely-used local accounts and for sessions authenticated through LDAP groups that have not been recently reviewed; alert on Virtual Office Portal access from external source addresses; and aggregate SSLVPN login events into the SIEM so brute-force and credential-stuffing bursts are visible. Because the endgame is ransomware, pair perimeter telemetry with host detections for mass file-rename / encryption behaviour on file servers.

Hardening / mitigation. Per the SANS ISC and vendor guidance: upgrade to firmware 7.3.0+; rotate every SonicWall account password after patching (treat the CVE as a credential-exposure event, not just a code fix); enforce MFA on all SSLVPN users, explicitly including those whose access derives from an LDAP default-group membership; audit the LDAP Default Group and remove implicit SSLVPN grants; restrict the Virtual Office Portal to internal networks only; and enable logging for all SSLVPN login attempts.

CVE-2024-40766 is an improper access control vulnerability affecting SonicWall firewalls' management interface and SSLVPN service across Gen 5-7 devices. Though patches have been available since August 2024, attackers continue exploiting it because organizations apply firmware updates without completing post-patch hardening.

SANS ISC

threat actors exploited CVE-2024-40766 to gain initial access through compromised SSL VPN credentials, then deployed Akira ransomware within hours

Arctic Wolf
vulnerability23 Jun 04:52Zmulti-sourceOpen finding →
Sources: SANS ISC · Arctic Wolf

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

  • Deep dive1
  • Threats1

Source distribution

  • attack.mitre.org4 (40%)
  • cisa.gov2 (20%)
  • arcticwolf.com1 (10%)
  • isc.sans.edu1 (10%)
  • psirt.global.sonicwall.com1 (10%)
  • sec.cloudapps.cisco.com1 (10%)