Detect SolarWinds Web Help Desk Deserialization of Untrusted Data (CVE-2025-26399) in Splunk
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
SPL Detection Query
index=* sourcetype IN ("WinEventLog:Security", "xmlwineventlog:security", "crowdstrike:events:sensor", "sysmon", "WinEventLog:Microsoft-Windows-Sysmon/Operational")
| eval is_whd_java = if(match(lower(ParentImage), "java\.exe") AND (match(lower(ParentCommandLine), "webhelpdesk") OR match(lower(Computer), "whd|helpdesk|webhelpdesk")), 1, 0)
| eval is_suspicious_child = if(match(lower(Image), "cmd\.exe|powershell\.exe|wscript\.exe|cscript\.exe|mshta\.exe|certutil\.exe|bitsadmin\.exe|curl\.exe|wget\.exe"), 1, 0)
| eval detection_type = case(
is_whd_java=1 AND is_suspicious_child=1, "WHD Java spawned suspicious process",
EventCode=4688 AND match(lower(ParentProcessName), "java\.exe") AND match(lower(NewProcessName), "cmd\.exe|powershell\.exe"), "Process creation - Java child",
true(), null()
)
| where isnotnull(detection_type)
| table _time, host, User, ParentImage, ParentCommandLine, Image, CommandLine, detection_type
| sort - _time
| union
[
search index=* sourcetype IN ("stream:tcp", "pan:traffic", "cisco:asa", "suricata") dest_port IN (4444, 9001, 1337, 8888)
| eval is_whd_src = if(match(lower(src_host), "whd|webhelpdesk|helpdesk"), 1, 0)
| where is_whd_src=1
| eval detection_type = "WHD host outbound to suspicious port (possible reverse shell C2)"
| table _time, src_ip, src_host, dest_ip, dest_port, detection_type
| sort - _time
]Detects CVE-2025-26399 exploitation in Splunk by correlating process creation events showing suspicious child processes under WHD's Java runtime, and network flow data showing outbound connections from WHD hosts to common reverse shell ports.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Legitimate administrative scripts triggered by Java-based schedulers on the WHD host
- Security scanning tools (Qualys, Nessus) generating process chains that resemble exploitation patterns
- Internal jump-box traffic from the WHD host to management systems on commonly abused ports
- Java garbage collection or JMX management connections generating unexpected outbound traffic
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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