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Upgrade to ProDetect Data Exfiltration via ICMP Tunneling in Splunk
Adversaries encode stolen data inside ICMP echo request/reply payloads to exfiltrate over a protocol that is frequently permitted outbound by firewalls even when all other egress is blocked. Public tools such as icmpsh, ptunnel, hans, and pingtunnel wrap a full bidirectional channel inside ICMP type 8/0 packets, and living-off-the-land variants simply abuse the built-in ping utility with oversized payloads (-l on Windows, -s on Linux/macOS) to smuggle data in repeated pings. This technique is a persistent detection gap because most EDR network telemetry (Microsoft Defender for Endpoint DeviceNetworkEvents, Sysmon Event ID 3, CrowdStrike NetworkConnectIP4) only instruments TCP/UDP connection setup and does not log ICMP traffic at all. Reliable detection therefore requires combining process-level visibility (ping.exe / ping binary invoked with abnormal packet-size or repeat-count flags, or unrecognized ICMP tunneling binaries) with network-layer telemetry from firewalls, NetFlow, or NDR/Zeek sensors that do record ICMP as a protocol.
MITRE ATT&CK
- Tactic
- Exfiltration
SPL Detection Query
index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
(
(Image="*\\ping.exe" AND (CommandLine="*-l *" OR CommandLine="*-t*"))
OR Image IN ("*\\icmpsh*", "*\\ptunnel*", "*\\hans.exe", "*\\pingtunnel*", "*\\icmptunnel*")
)
| rex field=CommandLine "-l\s+(?<PayloadSize>\d+)"
| eval Signal=case(
match(Image, "(?i)icmpsh|ptunnel|hans|pingtunnel|icmptunnel"), "KnownICMPTunnelTool",
isnotnull(PayloadSize) AND PayloadSize>1000, "OversizedPing",
match(CommandLine, "(?i)-t"), "ContinuousPing",
true(), "PingActivity"
)
| table _time, host, User, Image, CommandLine, PayloadSize, Signal
| sort - _timeSplunk detection using Sysmon Event ID 1 process creation to identify ping.exe invoked with an oversized ICMP payload (-l greater than 1000 bytes) or continuous mode (-t), as well as execution of dedicated ICMP tunneling binaries (icmpsh, ptunnel, hans, pingtunnel, icmptunnel). This is a host-side signal only — pair with firewall/NDR ICMP flow data for network-side confirmation since Sysmon does not log ICMP network traffic.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Network engineers performing MTU/fragmentation testing with large ping payloads
- IT monitoring dashboards using continuous ping for host availability checks
Other platforms for THREAT-Exfiltration-ICMPTunnel
Testing Methodology
Validate this detection against 3 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 1Oversized ICMP Payload via ping.exe
Expected signal: Sysmon Event ID 1 / DeviceProcessEvents: ping.exe process creation with CommandLine containing '-l 1400 -n 20'. No corresponding DeviceNetworkEvents entry will be generated, since MDE does not log ICMP traffic.
- Test 2Continuous Ping Simulation
Expected signal: Sysmon Event ID 1 / DeviceProcessEvents: ping.exe with CommandLine containing '-t'.
- Test 3Large ICMP Payload via ping (Linux/macOS)
Expected signal: Auditd EXECVE record for ping with arguments '-s 1400 -c 20 8.8.8.8'. Firewall/NDR sensors will show ICMP echo requests with 1400-byte payloads.
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Related Detections
Tactic Hub
Detection Variants (2)
Different telemetry and tradecraft for the same technique — pick the one that matches the data you collect.
- THREAT-DNSTunnel-ExfilDNS Tunneling for Covert Data ExfiltrationUse for network-side DNS visibility — Zeek/Infoblox resolver logs and pcap; catches tunneling from hosts with no endpoint agent.
- THREAT-DNSTunneling-ExfiltrationData Exfiltration via DNS Tunneling ToolsUse for endpoint DNS telemetry — Sysmon EID 22 / MDE DeviceDnsEvents; adds process attribution and tool fingerprints (iodine, dnscat2, DNSExfiltrator).