Array Networks AG and vxAG SSL VPN Gateway Unauthenticated Remote Code Execution (RCE) Vulnerability (CVE-2023-28461) Analysis and Mitigation Guide
Executive & SecOps Summary
SECOPS ASSESSMENTArray Networks Array AG Series and vxAG virtual appliances running version 9.4.0.481 and earlier
Unauthenticated remote attackers can browse the filesystem of the SSL VPN gateway by manipulating the 'flags' attribute in HTTP headers, leading to full Remote Code Execution (RCE)
Immediately upgrade to the patched firmware version released by the vendor, and restrict access to the management interface and VPN ports from untrusted networks
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Administrators must download and apply the latest patched firmware (version 9.4.0.482 or later) from the Array Networks Support Portal. Below is the standard CLI procedure to back up and upgrade the system image:
# Verify current version and back up configuration
show version
save config to backup_config_before_patch.cfg
# Download and apply the secure firmware image via SFTP/FTP
# (Refer to official vendor documentation for exact file paths)
system update image sftp://updates.arraynetworks.com/pub/ag/v9.4.0.482.bin
# Reboot the system to apply the patch
reboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict access to the Web Management Interface (e.g., port 8443) and VPN services using Access Control Lists (ACLs) to allow only trusted IP ranges.
# Restrict WebUI access to a trusted administrator subnet (e.g., 192.168.10.0/24)
configure terminal
access-list 100 permit ip 192.168.10.0 0.0.0.255 any
access-list 100 deny ip any any
# Apply the ACL to the WebUI management interface
webui access-group 100
end
write memory3. Log Audit & IoC Verification Commands
Inspect web server access logs for anomalous HTTP headers containing 'flags' or unauthorized access attempts to system directories.
# Scan web server access logs for suspicious 'flags' header manipulation
grep -Ei 'flags|/an_web/' /var/log/httpd/access_log
# Search for recently modified or created web shells in the web directory
find /var/www/html/ -mtime -10 -type f -name '*.php' -o -name '*.sh'Stop Exposing VPN Ports to the Internet — Switch to Zero-Trust Access
Eliminate public-facing VPN concentrators and firewall management ports with identity-first Zero-Trust Network Access.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2023-28461) is a critical security flaw in Array Networks AG Series and vxAG SSL VPN gateways. The root cause lies in the improper validation and lack of authentication when processing the 'flags' attribute within incoming HTTP request headers (CWE-287, CWE-306). This allows an unauthenticated attacker to bypass access controls and browse the internal filesystem of the gateway.
2. Exploitation Mechanics & Attack Scenario
An attacker sends a crafted HTTP request to the SSL VPN gateway's web interface. By injecting a specific 'flags' attribute into the HTTP header, the attacker bypasses authentication mechanisms and gains directory traversal capabilities. Subsequently, the attacker can locate sensitive configuration files or system binaries and exploit a vulnerable URL to upload or execute malicious payloads, achieving Remote Code Execution (RCE) with root privileges. This vulnerability is actively exploited in the wild and is listed in the CISA KEV catalog.
3. Infrastructure & Business Impact
Since SSL VPN gateways serve as the primary entry point to internal corporate networks, a compromise of this device is highly critical. Attackers can leverage this foothold to perform lateral movement, exfiltrate sensitive credentials, deploy ransomware, or intercept active user sessions, posing an existential threat to business continuity and data confidentiality.
Official Vendor Advisories & References
Array Networks Array AG Series and vxAG (9.4.0.481 and earlier) allow remote code execution. An attacker can browse the filesystem on the SSL VPN gateway using a flags attribute in an HTTP header without authentication. The product could then be exploited through a vulnerable URL. The 2023-03-09 vendor advisory stated "a new Array AG release with the fix will be available soon."
Frequently Asked SecOps Questions (CVE-2023-28461)
FAQQ1. How critical is CVE-2023-28461 and is it actively exploited in the wild?
CVE-2023-28461 is rated CVSS 9.8 (CRITICAL) with a 30-day EPSS exploitation probability of 68.1%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2023-28461?
Primary impacted vendors include array networks across array ag series, vxag. Scope summary: Array Networks Array AG Series and vxAG (physical and virtual appliances) versions 9.4.0.481 and earlier
Q3. What temporary mitigations or workarounds exist for CVE-2023-28461 before patching?
[Mitigation] Immediately upgrade to the patched firmware version released by the vendor, and restrict access to the management interface and VPN ports from untrusted networks Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2023-28461
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