CVE-2026-111793: Openwave Webtop Media Transcoder Active Exploitation — Detection and Remediation Guide

---
title: Direct Media Transcoder Access Bypassing Webmail
id: 8f3a2b91-4c7d-4e89-9a1b-2d3e4f5a6b7c
status: experimental
description: Detects direct HTTP requests to Openwave Media Transcoder endpoints that bypass the Webmail interface, indicating potential CVE-2026-111793 exploitation
references:
  - https://www.cisa.gov/known-exploited-vulnerabilities-catalog
author: Security Arsenal
date: 2026/11/10
tags:
  - attack.initial_access
  - attack.t1190
logsource:
  category: webserver
  product: generic
detection:
  selection:
    cs-uri-stem|contains:
      - '/transcoder'
      - '/mediaconverter'
      - '/webtop/transcode'
    cs-referer|contains:
      - ''
      - 'null'
  filter_webmail_proxy:
    cs-source|startswith:
      - '10.0.1.'
      - '10.0.2.'
  condition: selection and not filter_webmail_proxy
falsepositives:
  - Legitimate API integrations
  - Health check endpoints
  - Load balancer probes
level: high
---
title: Suspicious Document Upload to Transcoder
id: 7b2c9e14-8f3d-4a5b-9c1e-2f4a6d8e0b3c
status: experimental
description: Detects upload of potentially malicious document types to media transcoding services
references:
  - https://attack.mitre.org/techniques/T1190/
author: Security Arsenal
date: 2026/11/10
tags:
  - attack.initial_access
  - attack.t1190
logsource:
  category: webserver
  product: generic
detection:
  selection:
    cs-method: 'POST'
    cs-uri-stem|contains:
      - '/transcode'
      - '/convert'
      - '/upload'
    cs-uri-query|contains:
      - '.docm'
      - '.xlsm'
      - '.pptm'
      - '.zip'
      - '.rar'
      - '.7z'
      - '.js'
      - '.vbs'
      - '.hta'
falsepositives:
  - Legitimate document processing workflows
  - Administrative file conversions
level: medium
---
title: Transcoder Process Spawning Shell or Script Execution
id: 9d4e7f21-3b8c-4a9d-8e2f-1c5a7b9d0e2f
status: experimental
description: Detects media transcoder process spawning command shells or script interpreters, indicating successful exploitation
references:
  - https://attack.mitre.org/techniques/T1059/
author: Security Arsenal
date: 2026/11/10
tags:
  - attack.execution
  - attack.t1059
logsource:
  category: process_creation
  product: linux
detection:
  selection:
    ParentImage|contains:
      - '/transcoder'
      - '/mediaconverter'
      - 'openwave'
    Image|endswith:
      - '/bin/sh'
      - '/bin/bash'
      - '/usr/bin/python'
      - '/usr/bin/perl'
      - '/usr/bin/wget'
      - '/usr/bin/curl'
falsepositives:
  - Legitimate transcoder maintenance scripts
  - Administrative troubleshooting
level: critical

// Hunt for direct Media Transcoder access bypassing Webmail proxy
// Requires web server logs ingested via CEF, Syslog, or custom connector
let KnownWebmailProxies = dynamic(["10.0.1.10", "10.0.1.11", "10.0.2.5"]);
CommonSecurityLog
| where TimeGenerated > ago(7d)
| where DeviceVendor contains "Openwave" or RequestURL contains "transcoder" or RequestURL contains "webtop"
| where RequestMethod == "POST"
| where RequestURL has_any ("/transcoder", "/mediaconverter", "/transcode", "/convert")
| where SourceIP !in (KnownWebmailProxies)
| extend SuspiciousExtension = extract(@'\.(\w+)(\?|$)', 1, RequestURL)
| where SuspiciousExtension in ("docm", "xlsm", "pptm", "zip", "rar", "7z", "js", "vbs", "hta", "exe", "dll")
| project TimeGenerated, SourceIP, DestinationIP, RequestURL, RequestMethod, SuspiciousExtension, DeviceVendor, DeviceProduct
| order by TimeGenerated desc;

// Hunt for transcoder process anomalies on Linux hosts
Syslog
| where TimeGenerated > ago(7d)
| where ProcessName has_any ("transcoder", "mediaconverter", "openwave")
| where SyslogMessage has_any ("/bin/sh", "/bin/bash", "python", "perl", "wget", "curl", "nc", "netcat")
| project TimeGenerated, Computer, ProcessName, SyslogMessage, SeverityLevel
| order by TimeGenerated desc;

-- Hunt for suspicious child processes spawned by Media Transcoder
-- Target: Linux servers running Openwave Webtop
-- Indicator: Transcoder spawning shells, interpreters, or download utilities

SELECT Pid, Ppid, Name, Exe, CommandLine, Username, CreateTime
FROM pslist()
WHERE Name =~ '(sh|bash|python|perl|wget|curl|nc|netcat|socat)'
   AND Ppid IN (
       SELECT Pid
       FROM pslist()
       WHERE Exe =~ '(transcoder|mediaconverter|openwave|webtop)'
   )

-- Hunt for suspicious network connections from transcoder processes
SELECT Pid, Name, Exe, RemoteAddress, RemotePort, Status
FROM netstat()
WHERE Exe =~ '(transcoder|mediaconverter|openwave)'
   AND RemotePort IN (80, 443, 8080, 4444, 5555, 6666, 6667)
   AND RemoteAddress !~ '^(10\.|192\.168\.|172\.16\.|127\.)'

-- Hunt for recently modified transcoder configuration or executable files
SELECT FullPath, Size, Mtime, Ctime
FROM glob(globs='/opt/openwave/**/transcoder*')
WHERE Mtime > now() - 604800  -- Modified in last 7 days
ORDER BY Mtime DESC

# CVE-2026-111793 Openwave Webtop Media Transcoder - Exposure Check and Mitigation
# Run from privileged PowerShell session with network admin rights

# Configuration - UPDATE THESE VALUES FOR YOUR ENVIRONMENT
$OpenwaveServers = @("10.0.5.10", "10.0.5.11")  # Add your Openwave server IPs
$WebmailProxyIPs = @("10.0.1.10", "10.0.1.11")  # Add authorized Webmail proxy IPs
$TranscoderPorts = @(8080, 8443, 9090)           # Common transcoder ports

# 1. Check for direct transcoder access from unauthorized sources
Write-Host "[+] Checking for direct Media Transcoder access attempts..." -ForegroundColor Cyan
foreach ($server in $OpenwaveServers) {
    foreach ($port in $TranscoderPorts) {
        $result = Test-NetConnection -ComputerName $server -Port $port -WarningAction SilentlyContinue
        if ($result.TcpTestSucceeded) {
            Write-Host "[!] WARNING: Transcoder port $port accessible on $server" -ForegroundColor Red
            Write-Host "    This port should ONLY be accessible from Webmail proxy IPs" -ForegroundColor Yellow
        }
    }
}

# 2. Apply Windows Firewall rules to restrict transcoder access (if running on Windows)
Write-Host "`n[+] Applying firewall rules to restrict transcoder access..." -ForegroundColor Cyan
$RuleName = "CVE-2026-111793-Block-Direct-Transcoder"

# Remove existing rule if present
Remove-NetFirewallRule -DisplayName $RuleName -ErrorAction SilentlyContinue

# Create new rule blocking all transcoder traffic except from Webmail proxies
foreach ($port in $TranscoderPorts) {
    New-NetFirewallRule -DisplayName "$RuleName-Port$port" `
        -Direction Inbound `
        -Protocol TCP `
        -LocalPort $port `
        -RemoteAddress $WebmailProxyIPs `
        -Action Allow `
        -Enabled True `
        -Description "Allow transcoder access only from Webmail proxies - CVE-2026-111793 mitigation"
    
    New-NetFirewallRule -DisplayName "$RuleName-Port$port-Block" `
        -Direction Inbound `
        -Protocol TCP `
        -LocalPort $port `
        -Action Block `
        -Enabled True `
        -Description "Block direct transcoder access - CVE-2026-111793 mitigation"
}

Write-Host "[+] Firewall rules applied. Verify with: Get-NetFirewallRule -DisplayName '*CVE-2026-111793*'" -ForegroundColor Green

# 3. Generate network ACL recommendations for Linux/Network firewall
Write-Host "`n[+] Network ACL Recommendations for Linux/Network Firewall:" -ForegroundColor Cyan
Write-Host "# Add to iptables or network firewall:" -ForegroundColor Yellow
foreach ($proxy in $WebmailProxyIPs) {
    Write-Host "iptables -A INPUT -s $proxy -p tcp --dport 8080:9090 -j ACCEPT"
}
Write-Host "iptables -A INPUT -p tcp --dport 8080:9090 -j DROP"

# 4. Check for suspicious processes on local system (if applicable)
Write-Host "`n[+] Checking for suspicious transcoder child processes..." -ForegroundColor Cyan
$suspiciousProcesses = Get-Process | Where-Object {
    $_.ProcessName -match "transcoder|mediaconverter|openwave"
}

if ($suspiciousProcesses) {
    foreach ($proc in $suspiciousProcesses) {
        $children = Get-CimInstance Win32_Process | Where-Object { $_.ParentProcessId -eq $proc.Id }
        if ($children) {
            Write-Host "[!] Suspicious: Transcoder process $($proc.Id) has spawned child processes:" -ForegroundColor Red
            $children | Select-Object ProcessId, Name, CommandLine | Format-Table
        }
    }
} else {
    Write-Host "[i] No transcoder processes found on this system" -ForegroundColor Gray
}

# 5. Export IOC indicators for SIEM integration
Write-Host "`n[+] Exporting IOC indicators..." -ForegroundColor Cyan
$iocExport = @{
    "CVE" = "CVE-2026-111793"
    "VulnerableComponent" = "Openwave Webtop Media Transcoder"
    "SuspiciousPaths" = @("/transcoder", "/mediaconverter", "/webtop/transcode")
    "SuspiciousExtensions" = @("docm", "xlsm", "pptm", "zip", "rar", "7z", "js", "vbs", "hta")
    "DetectionQuery" = "Look for POST requests to transcoder endpoints from non-Webmail proxy IPs"
    "Mitigation" = "Restrict network access to transcoder service to authorized Webmail proxies only"
}

$iocExport | ConvertTo-Json | Out-File "CVE-2026-111793-IOCs.json"
Write-Host "[+] IOCs exported to CVE-2026-111793-IOCs.json" -ForegroundColor Green

Write-Host "`n[+] Verification complete. Review output above for exposure indicators." -ForegroundColor Green
Write-Host "[+] Next steps: Apply vendor patches, implement network segmentation, monitor for exploitation attempts" -ForegroundColor Cyan