Detect SolarWinds Web Help Desk Deserialization of Untrusted Data (CVE-2025-26399) in Google Chronicle
CVE-2025-26399 is a deserialization of untrusted data vulnerability (CWE-502) in SolarWinds Web Help Desk. Exploitation allows remote attackers to execute arbitrary code by sending maliciously crafted serialized Java objects to the application. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog, indicating active exploitation in the wild. SolarWinds Web Help Desk is widely deployed in enterprise and government environments for IT service management, making this a high-priority target for threat actors seeking privileged network access.
MITRE ATT&CK
- Tactic
- Initial Access Execution Persistence
YARA-L Detection Query
rule cve_2025_26399_whd_deserialization {
meta:
author = "df00tech Detection Engineering"
description = "Detects CVE-2025-26399 exploitation: SolarWinds Web Help Desk deserialization leading to suspicious process execution"
severity = "CRITICAL"
priority = "HIGH"
reference = "https://www.solarwinds.com/trust-center/security-advisories/cve-2025-26399"
yara_version = "YL2.0"
rule_version = "1.0"
events:
$process.metadata.event_type = "PROCESS_LAUNCH"
$process.principal.process.file.full_path = /(?i)java\.exe$/
(
$process.principal.process.command_line = /(?i)webhelpdesk/
or $process.principal.hostname = /(?i)(whd|webhelpdesk|helpdesk)/
)
$process.target.process.file.full_path = /(?i)(cmd\.exe|powershell\.exe|wscript\.exe|cscript\.exe|mshta\.exe|certutil\.exe|bitsadmin\.exe|curl\.exe|wget\.exe)/
condition:
$process
}Chronicle YARA-L 2.0 rule detecting CVE-2025-26399 exploitation by identifying process launch events where the SolarWinds WHD Java runtime spawns post-exploitation shell utilities.
Data Sources
Required Tables
False Positives & Tuning
- Legitimate Java administrative subprocesses on WHD hosts that invoke shell commands for routine tasks
- Monitoring agents co-located on the WHD host that use Java and spawn shell-based checks
- Automated Java-based update installers that invoke cmd.exe or PowerShell as part of patch application
- Custom integrations developed on the Web Help Desk platform that use shell utilities for workflow automation
Other platforms for CVE-2025-26399
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Simulate Java Deserialization Reverse Shell Spawn (Windows)
Expected signal: Sysmon Event ID 1: ProcessCreate with ParentImage=java.exe, Image=cmd.exe, CommandLine containing 'whoami'; DeviceProcessEvents in MDE showing same relationship
- Test 2Simulate WHD Java Process Network Beacon to C2 Port
Expected signal: Sysmon Event ID 3: NetworkConnect from java.exe to 127.0.0.1:4444; MDE DeviceNetworkEvents showing RemotePort=4444 from InitiatingProcessFileName=java.exe
- Test 3Simulate Malicious Class File Drop by WHD JVM (Linux)
Expected signal: Linux auditd or Sysmon-for-Linux: file creation event under /tmp owned by webhelpdesk user, initiated by java process; file content containing shell redirect syntax
- Test 4Reproduce Serialized Object HTTP POST to WHD Endpoint (Lab)
Expected signal: WAF/proxy logs showing HTTP POST with Content-Type: application/octet-stream and body beginning with AC ED 00 05; WHD application logs showing deserialization attempt (may log exception)
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