Web Service T1102
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
4 catalog events are tagged with this technique by at least one rule.
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Sysmon | Event ID 3 | Network connection |
| Sysmon | Event ID 22 | DNSEvent (DNS query) |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Authoring guide
Patterns shared across the 21 rules above: which fields they filter on, what specific values they look for, and what they exclude. The catalog normalizes field names across vendors so Sigma's Image, Elastic's process.name, and Splunk's process_name collapse into one row. Each rule contributes at most once per row.
Fields filtered most (13 distinct)
The fields most rules look at when detecting this technique. The How column shows the operators authors use (eq, wildcard, regex_match, match) and how often each appears. Sample values are concrete examples to start from, not an exhaustive list.
Top indicator values (377 distinct)
Specific (field, operator, value) combinations the rules check for, ranked by how many rules under this technique use each one. The Corpus reach column counts how many rules across the entire catalog (any technique) check the same combination. High numbers point to widely-used indicators that are likely noisy on their own; combine them with another condition for useful signal. Blank means the combination is specific to rules under this technique. Click a value to expand the rules under this technique that use it.
Exclusions (204 distinct)
Field/operator/value combinations excluded by rules under this technique (top-level not() clauses), sorted by how many rules exclude each. These are the false-positive paths the community has learned to filter out. A new rule that ignores the high-count entries here will likely fire on the same noisy paths. Click a value to expand the rules under this technique that exclude it.
Rules under this technique
Every rule in the catalog tagged with this technique, grouped by vendor. Click a rule title for its full predicates, exclusions, and indicators.
Sigma 13 rules
- Cloudflared Tunnel Connections Cleanup
- Cloudflared Tunnel Execution
- Communication To LocaltoNet Tunneling Service Initiated
- 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
- Suspicious Child Process Of Manage Engine ServiceDesk
- Suspicious Non-Browser Network Communication With Google API
- Suspicious Non-Browser Network Communication With Telegram API
Elastic 1 rule
Splunk 5 rules
- 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