DotNetNuke (DNN) Remote Code Execution via Weak Encryption and Cookie Deserialization (CVE-2018-15811)
Executive & SecOps Summary
SECOPS ASSESSMENTDotNetNuke (DNN) Platform versions 9.2.0 through 9.2.1
Attackers can exploit weak cryptographic algorithms to decrypt, forge, and inject malicious serialized .NET payloads into cookies, leading to Remote Code Execution (RCE)
Immediately upgrade DNN Platform to version 9.2.2 or higher, and regenerate the MachineKey in web.config
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
The primary remediation is to upgrade the DNN installation to version 9.2.2 or later. Use the following PowerShell command to verify the current version of the installed DNN assembly:
# Verify the current DotNetNuke assembly version
$assemblyPath = 'C:\inetpub\wwwroot\bin\DotNetNuke.dll'
if (Test-Path $assemblyPath) {
[System.Diagnostics.FileVersionInfo]::GetVersionInfo($assemblyPath).FileVersion
} else {
Write-Error 'DotNetNuke.dll not found. Please verify the path.'
}2. Temporary Workaround & Hardening Configuration
If an immediate upgrade is not feasible, secure the web.config file by explicitly defining strong cryptographic algorithms (such as HMACSHA256 and AES) and regenerating unique, cryptographically secure keys instead of relying on default or weak legacy configurations.
<!-- Hardened machineKey configuration in web.config -->
<configuration>
<system.web>
<machineKey validationKey='AutoGenerate,IsolateApps' decryptionKey='AutoGenerate,IsolateApps' validation='HMACSHA256' decryption='AES' />
</system.web>
</configuration>3. Log Audit & IoC Verification Commands
Inspect IIS logs for unusually large cookie values or suspicious serialized payloads, and monitor Windows Event Logs for anomalous child processes spawned by the IIS worker process.
# Search IIS log files for potential exploitation attempts targeting DNN cookies
grep -Ei '(dnnpersonalization|dotnetnuke)' /var/log/iis/*.log | grep -E ' (500|200) 'Block Exploits Instantly with Managed Virtual Patching Rules
Can't patch production immediately? Deploy managed WAF rules at the edge to intercept RCE, SQLi, and deserialization payloads before they hit your origin server.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2018-15811) exists in DotNetNuke (DNN) due to the use of a weak cryptographic algorithm (CWE-326) to protect sensitive input parameters and session cookies. The key generation and encryption routines employed by DNN in the affected versions lack sufficient entropy and cryptographic strength, allowing an attacker to predict or decrypt encrypted parameters and forge valid ciphertexts.
2. Exploitation Mechanics & Attack Scenario
An attacker can exploit this weakness by crafting a forged ciphertext that encapsulates a malicious serialized .NET object. When this payload is passed to the server via specific cookies (such as .DOTNETNUKE or DNNPersonalization), the application attempts to decrypt and deserialize the data. Because the decryption succeeds due to the weak cryptographic implementation, the .NET deserialization engine processes the untrusted payload, triggering arbitrary code execution under the security context of the IIS worker process (w3wp.exe).
3. Infrastructure & Business Impact
As a CISA KEV-listed vulnerability, this flaw has been actively exploited in the wild. Successful exploitation grants unauthenticated remote attackers full control over the hosting web server. This can lead to complete database compromise, lateral movement within the internal network, and deployment of ransomware, posing an extreme risk to organizational infrastructure and data confidentiality.
Official Vendor Advisories & References
DNN (aka DotNetNuke) 9.2 through 9.2.1 uses a weak encryption algorithm to protect input parameters.
Frequently Asked SecOps Questions (CVE-2018-15811)
FAQQ1. How critical is CVE-2018-15811 and is it actively exploited in the wild?
CVE-2018-15811 is rated CVSS 7.5 (HIGH) with a 30-day EPSS exploitation probability of 76.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2018-15811?
Primary impacted vendors include dnnsoftware across dotnetnuke. Scope summary: DotNetNuke (DNN) Platform versions 9.2.0 and 9.2.1
Q3. What temporary mitigations or workarounds exist for CVE-2018-15811 before patching?
[Mitigation] Immediately upgrade DNN Platform to version 9.2.2 or higher, and regenerate the MachineKey in web.config Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
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