SonicWall SonicOS SSLVPN Improper Authentication Vulnerability (CVE-2024-53704)
Published In CISA KEV since Sources: CVE.org, pwn.watch
What is affected, what to do
An Improper Authentication vulnerability in the SSLVPN authentication mechanism allows a remote attacker to bypass authentication.
The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.
- Affected
- SonicWall SonicOS
eq 7.1.1-7058 and older versions..7.1.1-7058 and older versions - SonicWall SonicOS
eq 7.1.2-7019..7.1.2-7019 - SonicWall SonicOS
eq 8.0.0-8035..8.0.0-8035
- SonicWall SonicOS
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Metrics
9.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
9.8
CVSS v3
Severity Critical on the scale from 0 to 10.
Source: CVE.org, pwn.watch
95.3 %
EPSS score
High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
Source: FIRST EPSS, percentile 99.87
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 261.29 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploitedSource: VulnCheck KEV (opens in a new tab), CERT.at How we classify
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 9.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 9.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 95.3 %
- High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 99.87
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- Actively exploited
- Published
In CISA KEV since
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossaryCWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-287
Response and mitigation
Why act now?
Prioritisation rationale
This flaw is exploitable over the network with no authentication and no user interaction, on an edge device that is internet-facing by design. Public technical exploitation details exist, and its exploitation likelihood sits among the very highest of all tracked CVEs. CISA flags it as used in ransomware campaigns; the typical chain is hijacking a VPN session for initial access, followed by AD reconnaissance, data exfiltration and encryption. Treat every internet-exposed SonicWall with SSLVPN enabled as critical, to be remediated within hours rather than in the regular patch cycle. Only devices with SSLVPN disabled or no WAN exposure warrant lower priority.
Runbook step 1
Immediate response (0-24 h)
- Establish exposure: Inventory every SonicWall firewall with SSLVPN enabled (Gen7, especially firmware in the SonicOS 7.1.1-7040 to 7.1.1-7058 range). Confirm whether the SSLVPN portal is internet-reachable; the default is often TCP 4433, otherwise 443.
- Upgrade firmware: Patches are available from the vendor. Look up the fixed builds for each affected product line (Gen7, and 8.x where applicable) in the SonicWall PSIRT advisory for CVE-2024-53704, then deploy them. Verify firmware integrity before rollout.
- If you cannot patch today: Disable SSLVPN on the WAN zone, or restrict it with an access rule to known source ranges (partners, admin jump hosts). This removes the attack surface.
- Kill active sessions: Terminate all SSLVPN sessions now. The attack hijacks already-authenticated sessions without needing credentials, so a session reset evicts any attacker riding a stolen session.
- Rotate credentials: Reset passwords for SSLVPN users and local firewall admins. Also rotate LDAP/RADIUS bind accounts stored on the appliance, and re-enrol TOTP seeds if you find signs of compromise.
- Preserve evidence: Export firewall logs, SSLVPN login history and configuration backups off-box before upgrades or reboots flush on-device buffers. You need these for forensic scoping and any NIS2 notification decision.
Runbook step 2
Mitigation layers
- Network segmentation: Place SSLVPN clients in a dedicated zone with least-privilege rules. Allow no blanket access to server VLANs, domain controllers or backup networks. Permit AD-relevant ports (TCP 88, 389, 445, 3389) only to explicitly required targets.
- Perimeter restriction: Enable Geo-IP and botnet filtering on the SSLVPN zone. Optionally, publish the portal only behind a reverse proxy or ZTNA broker that performs its own authentication.
- Management hardening: Disable HTTPS and SSH management on WAN interfaces. Allow administration only from a dedicated management VLAN.
- IAM: Enforce MFA for SSLVPN. Note that MFA does not stop hijacking of an existing session, so it is not a substitute for patching. Keep session and idle timeouts short to shrink the hijack window.
- IPS/inspection: Where TLS termination or inspection sits in front of the portal, block requests to
/cgi-bin/sslvpnclientthat carry an anomalousswapcookie, such as a Base64 value made of null bytes (AAAAAAAA…). Also keep SonicWall IPS signatures current.
Runbook step 3
Detection rules
- SonicWall syslog (SSLVPN events): Flag established SSLVPN sessions with no preceding username/password login event. Also flag users with concurrent sessions from two different source IPs. Example SPL:
index=fw sourcetype=sonicwall msg="*SSL VPN*" | stats dc(src_ip) as ips by user | where ips>1 - Unexpected user disconnects: Hijacking can terminate the legitimate session. Correlate helpdesk tickets about sudden VPN drops with logs. Look for logouts followed within seconds by activity for the same session or user from a foreign IP.
- Web/proxy logs (where TLS is terminated): Hunt for requests to
/cgi-bin/sslvpnclientwithCookie: swap=containing a null-byte Base64 pattern. Sigma shape:cs-uri-stem|contains: '/cgi-bin/sslvpnclient'ANDcs-cookie|re: 'swap=A{20,}' - Post-access activity (Zeek/EDR): Monitor traffic sourced from the SSLVPN address pool for reconnaissance and lateral movement. This includes bulk SMB/LDAP queries, RDP fan-out, Kerberoasting (Windows Event 4769 with RC4 encryption) and new services (Event 7045). Also watch Sysmon EID 1 for
AdFind,nltest,rcloneandvssadmin delete shadows. - Configuration tampering: Alert on new local admin accounts, modified access rules or NAT policies, and configuration exports in the appliance audit log.
- SonicWall syslog (SSLVPN events): Flag established SSLVPN sessions with no preceding username/password login event. Also flag users with concurrent sessions from two different source IPs. Example SPL:
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
An Improper Authentication vulnerability in the SSLVPN authentication mechanism allows a remote attacker to bypass authentication.
Source: CISA KEV Catalog, cvelistv5, NVD (NIST), CVE.org (MITRE), pwn.watch
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| SonicWall | SonicOS |
|
|
Vendors and products
Affected operating systems
| Other | sonicwall | sonicos | 7.1.2-7019 |
| Other | sonicwall | sonicos | 8.0.0-8035 |
| Other | sonicwall | sonicos | — |
Weakness classes (CWE)
CWE-287Improper Authentication
Class
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
Entry at MITRE CWE-287
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited |
References & sources
- psirt.global.sonicwall.comSonicWall advisory: SonicWall SonicOSVendor advisory, pwn-watch
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2024-53704government-resource
- cert.atCERT.at: Update#1: Schwerwiegende Sicherheitslücken in Sonicwall SSL-VPN - aktiv ausgenutztcert-at
- pwn.watchpwn.watch: SonicWall SonicOS: SonicOS SSLVPN Improper Authentication Vulnerabilitypwn-watch
- NVD (NIST)NVD: CVE-2024-53704pwn-watch
- cisa.govCISA Known Exploited Vulnerabilities Catalogpwn-watch
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<a href="https://intel.neosec.eu/en/cve/CVE-2024-53704"><img src="https://intel.neosec.eu/badge/cve/CVE-2024-53704.svg?lang=en" alt="CVE-2024-53704 – NEOSEC Intel" height="20"></a>