Detect Web Service in Microsoft Sentinel
Adversaries may use an existing, legitimate external web service as a means for relaying data to/from a compromised system. Popular websites and cloud services such as Google Drive, OneDrive, Dropbox, Pastebin, GitHub, and Discord may act as C2 channels due to the high likelihood that hosts within a network already communicate with them. This provides cover in expected noise and takes advantage of SSL/TLS encryption offered by these providers. Use of web services also protects back-end C2 infrastructure from discovery through malware binary analysis while enabling operational resiliency through dynamic infrastructure changes.
MITRE ATT&CK
- Tactic
- Command and Control
- Technique
- T1102 Web Service
- Canonical reference
- https://attack.mitre.org/techniques/T1102/
KQL Detection Query
let LegitBrowsers = dynamic(["chrome.exe", "firefox.exe", "msedge.exe", "iexplore.exe", "safari.exe", "opera.exe", "brave.exe"]);
let WebServiceDomains = dynamic([
"pastebin.com", "paste.ee", "ghostbin.co",
"api.github.com", "raw.githubusercontent.com", "gist.github.com",
"graph.microsoft.com", "onedrive.live.com", "api.onedrive.com",
"www.googleapis.com", "drive.google.com", "storage.googleapis.com",
"api.dropboxapi.com", "content.dropboxapi.com",
"discord.com", "discordapp.com", "cdn.discordapp.com",
"api.telegram.org",
"slack.com", "api.slack.com",
"firebaseio.com", "firebase.googleapis.com",
"api.notion.so",
"gitee.com",
"top4top.io"
]);
DeviceNetworkEvents
| where Timestamp > ago(24h)
| where RemoteUrl has_any (WebServiceDomains) or RemoteIPType == "Public"
| join kind=inner (
DeviceProcessEvents
| where Timestamp > ago(24h)
| project DeviceId, ProcessId=tolong(ProcessId), FileName, ProcessCommandLine, InitiatingProcessFileName, AccountName, SHA256
) on DeviceId
| where RemoteUrl has_any (WebServiceDomains)
| where not(InitiatingProcessFileName has_any (LegitBrowsers))
| where not(FileName has_any (LegitBrowsers))
| where FileName !in~ ("OneDriveSetup.exe", "OneDrive.exe", "googledrivesync.exe", "dropbox.exe", "slack.exe", "teams.exe", "discord.exe")
| extend SuspiciousProcess = FileName in~ ("powershell.exe", "pwsh.exe", "cmd.exe", "wscript.exe", "cscript.exe", "mshta.exe", "rundll32.exe", "regsvr32.exe", "certutil.exe", "bitsadmin.exe", "curl.exe", "wget.exe")
| extend ScriptingProcess = FileName in~ ("python.exe", "python3.exe", "ruby.exe", "perl.exe", "node.exe", "wscript.exe", "cscript.exe")
| extend UnusualParent = InitiatingProcessFileName in~ ("winword.exe", "excel.exe", "powerpnt.exe", "outlook.exe", "acrobat.exe", "acrord32.exe")
| project Timestamp, DeviceName, AccountName, FileName, ProcessCommandLine,
InitiatingProcessFileName, RemoteUrl, RemoteIP, RemotePort,
SuspiciousProcess, ScriptingProcess, UnusualParent, SHA256
| sort by Timestamp descDetects non-browser processes making network connections to known web service platforms commonly abused for C2 (Pastebin, GitHub, Google Drive, OneDrive, Dropbox, Discord, Telegram, Firebase, etc.). Joins DeviceNetworkEvents with DeviceProcessEvents to identify the initiating process. Excludes known legitimate cloud sync clients and browsers. Flags scripting interpreters, LOLBins, and document applications as high-suspicion initiators. Effective against malware families like BoomBox (Dropbox), Nightdoor (OneDrive/Google Drive), Carbon (Pastebin), and Raspberry Robin (Discord).
Data Sources
Required Tables
False Positives & Tuning
- Legitimate developer tools or CI/CD pipelines making API calls to GitHub, Firebase, or Google APIs
- IT management tools and monitoring agents that poll cloud APIs for configuration or telemetry upload
- Custom line-of-business applications built on cloud storage APIs (OneDrive, Google Drive SDK integrations)
- PowerShell scripts used legitimately by administrators to upload logs or reports to cloud storage
- Antivirus or endpoint agents uploading telemetry to cloud-hosted collection endpoints
Other platforms for T1102
Testing Methodology
Validate this detection against 5 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 Dead Drop Resolver via Pastebin
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe, CommandLine containing 'Net.WebClient' and 'pastebin.com'. Sysmon Event ID 3: Network Connection to pastebin.com on port 443. Sysmon Event ID 22: DNS query for pastebin.com. PowerShell ScriptBlock Log Event ID 4104 with the full command.
- Test 2Simulated OneDrive C2 Channel via Microsoft Graph API
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe, CommandLine containing 'Invoke-RestMethod' and 'graph.microsoft.com'. Sysmon Event ID 3: Network Connection to graph.microsoft.com on port 443. Sysmon Event ID 22: DNS query for graph.microsoft.com.
- Test 3Curl-based GitHub Raw Content Retrieval (Linux/macOS)
Expected signal: Syslog/auditd: execve syscall for curl with arguments containing raw.githubusercontent.com. Network connection to 185.199.x.x (GitHub CDN) on port 443. Linux audit log: SYSCALL record with comm=curl, SOCKADDR with dest IP. File creation at /tmp/df00tech-test-payload.txt.
- Test 4Discord Webhook C2 Simulation
Expected signal: Sysmon Event ID 1: Process Create with Image=powershell.exe, CommandLine containing 'discord.com' and 'Invoke-RestMethod'. Sysmon Event ID 3: Network Connection to discord.com port 443. Sysmon Event ID 22: DNS query for discord.com. The request will fail with HTTP 401/404 but the network telemetry will still be generated.
- Test 5Python-based Telegram Bot API C2 Simulation
Expected signal: Sysmon Event ID 1: Process Create with Image=python.exe, CommandLine containing 'api.telegram.org'. Sysmon Event ID 3: Network Connection to api.telegram.org port 443. Sysmon Event ID 22: DNS query for api.telegram.org. The request will return HTTP 401 (invalid token) but network telemetry is generated.
References (10)
- https://attack.mitre.org/techniques/T1102/
- https://www.broadcom.com/support/security-center/protection-bulletin/birdyclient-malware-leverages-microsoft-graph-api-for-c-c-communication
- https://www.welivesecurity.com/en/eset-research/evasivepanda-apt-group-uses-update-channels-of-legitimate-applications-for-cyberespionage/
- https://symantec-enterprise-blogs.security.com/threat-intelligence/daggerfly-apt-actor-macos
- https://unit42.paloaltonetworks.com/latrodectus-cybercrime-affiliate-activity/
- https://www.microsoft.com/en-us/security/blog/2021/05/28/breaking-down-nobelium-latest-early-stage-toolset/
- https://www.cybereason.com/blog/molerats-in-the-cloud-new-malware-arsenal-abuses-cloud-platforms-in-middle-east-espionage-campaign
- https://blog.talosintelligence.com/2018/08/rocke-champion-of-monero-miners.html
- https://hp.com/h20195/v2/getpdf.aspx/a00127091enw.pdf
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1102/T1102.md
Unlock Pro Content
Get the full detection package for T1102 including response playbook, investigation guide, and atomic red team tests.