Detect Web Services in Splunk
Adversaries may register for web services that can be used during targeting. A variety of popular websites exist for adversaries to register for a web-based service that can be abused during later stages of the adversary lifecycle, such as during Command and Control (Web Service), Exfiltration Over Web Service, or Phishing. Using common services such as those offered by Google, GitHub, Discord, Telegram, or Dropbox makes it easier for adversaries to hide in expected noise. Real-world threat actors including APT29, Turla, Earth Lusca, Mustang Panda, Lazarus Group, HAFNIUM, MuddyWater, and Contagious Interview have all leveraged legitimate web platforms to host malware, stage C2 infrastructure, or receive exfiltrated data. Because the adversary's actual registration of these accounts occurs entirely outside the victim environment, detection pivots to identifying the operational use of these platforms by suspicious processes within monitored endpoints.
MITRE ATT&CK
- Tactic
- Resource Development
- Technique
- T1583 Acquire Infrastructure
- Sub-technique
- T1583.006 Web Services
- Canonical reference
- https://attack.mitre.org/techniques/T1583/006/
SPL Detection Query
index=wineventlog sourcetype="XmlWinEventLog:Microsoft-Windows-Sysmon/Operational" EventCode=3
| eval proc=lower(Image)
| eval dest_host=lower(DestinationHostname)
| where match(proc, "(powershell\.exe|pwsh\.exe|cmd\.exe|mshta\.exe|wscript\.exe|cscript\.exe|rundll32\.exe|regsvr32\.exe|certutil\.exe|bitsadmin\.exe|curl\.exe|python\.exe|pythonw\.exe|python3\.exe|java\.exe|javaw\.exe|msbuild\.exe|installutil\.exe)")
| where match(dest_host, "(api\.github\.com|raw\.githubusercontent\.com|gist\.githubusercontent\.com|api\.dropboxapi\.com|content\.dropboxapi\.com|api\.telegram\.org|discord\.com|discordapp\.com|pastebin\.com|rentry\.co|paste\.ee|hastebin\.com|firebaseio\.com|firebase\.google\.com|trycloudflare\.com|workers\.dev|notion\.so|terabox\.com|filemail\.com|storage\.googleapis\.com|drive\.google\.com)")
| eval IsPayloadRetrieve=if(match(dest_host, "(raw\.githubusercontent\.com|gist\.githubusercontent\.com|pastebin\.com|rentry\.co|paste\.ee|hastebin\.com)"), 1, 0)
| eval IsC2Channel=if(match(dest_host, "(api\.telegram\.org|discord\.com|discordapp\.com|firebaseio\.com|trycloudflare\.com|workers\.dev)"), 1, 0)
| eval IsDataExfil=if(match(dest_host, "(api\.dropboxapi\.com|content\.dropboxapi\.com|drive\.google\.com|storage\.googleapis\.com|terabox\.com|filemail\.com)"), 1, 0)
| eval SuspicionScore=IsPayloadRetrieve + IsC2Channel + IsDataExfil
| table _time, host, User, Image, CommandLine, ParentImage, ParentCommandLine, DestinationHostname, DestinationIp, DestinationPort, IsPayloadRetrieve, IsC2Channel, IsDataExfil, SuspicionScore
| sort - _timeDetects suspicious scripting engines and LOLBins making outbound network connections to legitimate web service platforms known to be abused for C2 staging, payload retrieval, and exfiltration. Uses Sysmon Event ID 3 (Network Connection) which captures DestinationHostname before DNS resolution, enabling reliable domain-based matching. Each connection is classified into payload retrieval (GitHub raw, Pastebin), C2 channel (Telegram API, Discord webhooks, Firebase, Cloudflare Tunnel), or data exfiltration (Dropbox API, Google Drive, file sharing services) categories with a cumulative suspicion score.
Data Sources
Required Sourcetypes
False Positives & Tuning
- Developer workstations running build pipelines, CI runners, or git clients that call api.github.com from powershell.exe or python.exe as part of automated workflows
- Security tooling and vulnerability scanners that use Python or Java to pull threat intelligence feeds from GitHub or Pastebin
- Legitimate Python or Java applications using the Dropbox, Google Drive, or OneDrive SDK for authorized file sync and backup
- IT automation scripts using curl.exe or PowerShell to post notifications to Teams/Discord/Slack webhooks as part of sanctioned alerting pipelines
- Software installers or package managers (pip, npm, maven) fetching packages from Google Storage or Firebase CDN during first-run or updates
Other platforms for T1583.006
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 1PowerShell Payload Retrieval from GitHub Raw Content
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe, CommandLine containing 'Net.WebClient' and 'raw.githubusercontent.com'. Sysmon Event ID 3: Network Connection to raw.githubusercontent.com:443. Sysmon Event ID 22: DNS Query for raw.githubusercontent.com from powershell.exe. PowerShell ScriptBlock Log Event ID 4104 with the full script. DeviceNetworkEvents in MDE will show RemoteUrl matching raw.githubusercontent.com.
- Test 2Data Exfiltration Simulation to Dropbox API via curl
Expected signal: Sysmon Event ID 3: Network Connection from curl.exe to content.dropboxapi.com:443. Sysmon Event ID 22: DNS Query for content.dropboxapi.com from curl.exe. Sysmon Event ID 11: File Create for the temp file. DeviceNetworkEvents in MDE will show InitiatingProcessFileName=curl.exe, RemoteUrl matching content.dropboxapi.com. The HTTP response will be 401, but the connection event is logged regardless.
- Test 3Telegram Bot API C2 Polling Simulation
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe, CommandLine containing 'api.telegram.org' and 'getUpdates'. Sysmon Event ID 3: Network Connection from powershell.exe to api.telegram.org:443. Sysmon Event ID 22: DNS Query for api.telegram.org from powershell.exe. PowerShell ScriptBlock Log Event ID 4104 capturing the Invoke-RestMethod call. DeviceNetworkEvents in MDE shows RemoteUrl matching api.telegram.org.
- Test 4Multi-Stage Web Service Abuse — Payload Retrieval Then C2 Check-In
Expected signal: Sysmon Event ID 1: Single powershell.exe process with long command line containing both pastebin.com and discord.com references. Sysmon Event ID 3: Two network connection events — one to pastebin.com:443, one to discord.com:443. Sysmon Event ID 22: Two DNS queries — pastebin.com and discord.com — both initiated by powershell.exe. PowerShell ScriptBlock Log Event ID 4104 with the full script. DeviceNetworkEvents in MDE shows two entries with RemoteUrl matching pastebin.com and discord.com respectively.
References (10)
- https://attack.mitre.org/techniques/T1583/006/
- https://services.google.com/fh/files/misc/rpt-apt29-hammertoss-stealthy-tactics-define-en.pdf
- https://thehackernews.com/expert-insights/2024/05/github-abuse-flaw-shows-why-we-cant.html
- https://www.trendmicro.com/content/dam/trendmicro/global/en/research/22/a/earth-lusca-employs-sophisticated-infrastructure-varied-tools-and-techniques/technical-brief-delving-deep-an-analysis-of-earth-lusca-operations.pdf
- https://www.welivesecurity.com/2020/12/02/turla-crutch-keeping-back-door-open/
- https://www.anomali.com/blog/probable-iranian-cyber-actors-static-kitten-conducting-cyberespionage-campaign-targeting-uae-and-kuwait-government-agencies
- https://www.proofpoint.com/us/blog/threat-insight/security-brief-ta450-uses-embedded-links-pdf-attachments-latest-campaign
- https://threatconnect.com/blog/infrastructure-research-hunting/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1102/T1102.md
- https://learn.microsoft.com/en-us/defender-endpoint/advanced-hunting-devicenetworkevents-table
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