Detect Time Based Checks in Splunk
Adversaries may employ various time-based methods to detect virtualization and analysis environments, particularly those that attempt to manipulate time mechanisms to simulate longer elapses of time. This includes using GetTickCount and GetSystemTimeAsFileTime to detect time acceleration in sandboxes, implementing long sleep delays (minutes to hours) to outlast sandbox analysis timeouts, checking system uptime to verify the machine has been running for a reasonable period, computing execution timing differences before and after sleep to detect sandbox time manipulation, and using API hammering (excessive printf or I/O calls) to delay execution. Notable examples include SUNBURST (2-week dormancy), Ursnif (30-minute delay), Bumblebee (hardcoded and randomized sleep intervals), and TrickBot (printf-based API hammering).
MITRE ATT&CK
- Tactic
- Defense Evasion Discovery
- Technique
- T1497 Virtualization/Sandbox Evasion
- Sub-technique
- T1497.003 Time Based Checks
- Canonical reference
- https://attack.mitre.org/techniques/T1497/003/
SPL Detection Query
index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=1
| eval CommandLine=lower(CommandLine)
| eval TimingAPICheck=if(match(CommandLine, "(gettickcount|getsystemtimeasfiletime|queryperformancecounter|ntquerysystemtime|timegettime)"), 1, 0)
| eval LongTimeout=if(match(Image, "(?i)timeout\.exe") AND match(CommandLine, "timeout\s+/t\s+\d{3,}"), 1, 0)
| eval LongPingSleep=if(match(Image, "(?i)ping\.exe") AND match(CommandLine, "ping\s+-n\s+\d{3,}\s+127\.0\.0\.1"), 1, 0)
| eval ScriptSleep=if(match(CommandLine, "(start-sleep|wscript\.sleep|thread\.sleep)"), 1, 0)
| eval UptimeQuery=if(match(CommandLine, "(lastbootuptime|boot time|net statistics)"), 1, 0)
| eval SuspicionScore=TimingAPICheck*2 + LongTimeout*2 + LongPingSleep*2 + ScriptSleep + UptimeQuery
| where SuspicionScore > 0
| table _time, host, User, Image, CommandLine, ParentImage, ParentCommandLine, TimingAPICheck, LongTimeout, LongPingSleep, ScriptSleep, UptimeQuery, SuspicionScore
| sort - _timeDetects time-based sandbox evasion via Sysmon process creation events. Identifies timing API references, extended timeout/ping delays (100+ seconds), script-based sleep commands, and system uptime queries. Extended delays are weighted higher as they are more likely to be evasion-motivated.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Batch scripts with legitimate timeout/ping delays
- PowerShell scripts using Start-Sleep for API rate limiting
- System monitoring tools checking uptime
- Application installers pausing between phases
Other platforms for T1497.003
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 1Extended timeout delay for sandbox evasion
Expected signal: Sysmon Event ID 1: Process Create for timeout.exe with '/t 180' argument. The process will be visible in task list for the duration of the delay. Security Event ID 4688 with command line.
- Test 2Ping-based sleep for sandbox evasion
Expected signal: Sysmon Event ID 1: Process Create for ping.exe with '-n 300 127.0.0.1' arguments. Sysmon Event ID 3: Network Connection events to 127.0.0.1 (loopback).
- Test 3WMI uptime check for sandbox detection
Expected signal: Sysmon Event ID 1: Process Create for wmic.exe with 'os get lastbootuptime' arguments. WMI Operational log entry for Win32_OperatingSystem query.
References (6)
- https://attack.mitre.org/techniques/T1497/003/
- https://www.isaca.org/resources/isaca-journal/issues/2017/volume-6/evasive-malware-tricks-how-malware-evades-detection-by-sandboxes
- https://www.fireeye.com/blog/threat-research/2020/12/evasive-attacker-leverages-solarwinds-supply-chain-compromises-with-sunburst-backdoor.html
- https://www.welivesecurity.com/2019/07/okrum-ke3chang-malware/
- https://unit42.paloaltonetworks.com/atoms/bendybear/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1497.003/T1497.003.md
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