Web Service T1102
Tactic: Command & Control
Adversaries may use an existing, legitimate external Web service as a means for relaying data to/from a compromised system. Popular websites, cloud services, and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google, Microsoft, or Twitter, makes it easier for adversaries to hide in expected noise. Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.
Events covered
20 catalog events are tagged with this technique by at least one rule.
Authoring guide
These 72 rules share fields, values, and exclusions.
Fields filtered most (73 distinct)
These fields appear most often in rule filters.
Top indicator values (1601 distinct)
These values appear most often in rule predicates.
Exclusions (496 distinct)
These values appear most often in top-level exclusions.
Rules under this technique
These vendors publish rules tagged with this technique.
Sigma 19 rules
- Cloudflared Tunnel Connections Cleanup
- Cloudflared Tunnel Execution
- Communication To LocaltoNet Tunneling Service Initiated
- Communication To LocaltoNet Tunneling Service Initiated - Linux
- Communication To Ngrok Tunneling Service - Linux
- Communication To Ngrok Tunneling Service Initiated
- Github Self-Hosted Runner Execution
- Network Connection Initiated To AzureWebsites.NET By Non-Browser Process
- New Connection Initiated To Potential Dead Drop Resolver Domain
- Potentially Suspicious Azure Front Door Connection
- Potentially Suspicious Network Connection To Notion API
- Process Initiated Network Connection To Ngrok Domain
- PwnDrp Access
- Raw Paste Service Access
- Suspicious Child Process Of Manage Engine ServiceDesk
- Suspicious Non-Browser Network Communication With Google API
- Suspicious Non-Browser Network Communication With Telegram API
- Telegram API Access
- Telegram Bot API Request
Elastic 30 rules
- Attempt to establish VScode Remote Tunnel
- AWS CLI Command with Custom Endpoint URL
- AWS SNS Rare Protocol Subscription by User
- AWS SNS Topic Message Publish by Rare User
- Connection to Common Large Language Model Endpoints
- Connection to Commonly Abused Web Services
- Connection to WebService by a Signed Binary Proxy
- Connection to WebService by an Unsigned Binary
- DNS Request by Recently Created Executable
- DNS Request to Crypto Miner Service
- DNS Request to Crypto/DHT Services
- DNS Request to Dynamic DNS via Suspicious Executable
- DNS Request to IP Lookup Service from Suspicious Working Directory
- DNS Request to Suspicious File Upload/Download Service
- DNS Request to Suspicious Top Level Domain
- DNS to Commonly Abused Web Services
- Google Calendar C2 via Script Interpreter
- Linux Telegram API Request
- Network Connection to OAST Domain via Script Interpreter
- Potential Etherhiding C2 via Blockchain Connection
- Potential VScode Remote Tunnel Established
- Statistical Model Detected C2 Beaconing Activity
- Statistical Model Detected C2 Beaconing Activity with High Confidence
- Suspicious AWS S3 Connection via Script Interpreter
- Suspicious Command and Control via Internet Explorer
- Suspicious Curl to Google App Script Endpoint
- Suspicious File Downloaded from Google Drive
- Uncommon DNS Request via Bun or Node.js
- Unusual Network Connection to Suspicious Web Service
- Unusual Web Request
Splunk 6 rules
- Linux Ngrok Reverse Proxy Usage
- Ngrok Reverse Proxy on Network
- Potential Telegram API Request Via CommandLine
- Windows Abused Web Services
- Windows DNS Query Request by Telegram Bot API
- Windows Ngrok Reverse Proxy Usage
Kusto 17 rules
- A host is potentially running a hacking tool (ASIM Web Session schema)
- ApexOne - Suspicious connections
- Cisco Cloud Security - Hack Tool User-Agent Detected
- Cisco SE - Possible webshell
- Cisco WSA - Multiple errors to resource from risky category
- Cisco WSA - Multiple errors to URL
- Cisco WSA - Unexpected URL
- CreepyDrive request URL sequence
- CreepyDrive URLs
- Detect requests for an uncommon resources on the web (ASIM Web Session)
- Netskope - Suspicious Application Activity (Low Confidence / Risky App)
- Ngrok Reverse Proxy on Network (ASIM DNS Solution)
- NRT Squid proxy events related to mining pools
- Possible Phishing with CSL and Network Sessions
- Powershell Empire Cmdlets Executed in Command Line
- Request for single resource on domain
- Squid proxy events related to mining pools