Hayabusa medium test sigma

Suspicious Non-Browser Network Communication With Telegram API

Detects an a non-browser process interacting with the Telegram API which could indicate use of a covert C2

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Detection Logic

{
  "network_connection": {
    "EventID": 3,
    "Channel": "Microsoft-Windows-Sysmon/Operational"
  },
  "selection": {
    "DestinationHostname
| contains": "api.telegram.org"
  },
  "filter_main_brave": {
    "Image
| endswith": "\\brave.exe"
  },
  "filter_main_chrome": {
    "Image": [
      "C:\\Program Files\\Google\\Chrome\\Application\\chrome.exe",
      "C:\\Program Files (x86)\\Google\\Chrome\\Application\\chrome.exe"
    ]
  },
  "filter_main_firefox": {
    "Image": [
      "C:\\Program Files\\Mozilla Firefox\\firefox.exe",
      "C:\\Program Files (x86)\\Mozilla Firefox\\firefox.exe"
    ]
  },
  "filter_main_ie": {
    "Image": [
      "C:\\Program Files (x86)\\Internet Explorer\\iexplore.exe",
      "C:\\Program Files\\Internet Explorer\\iexplore.exe"
    ]
  },
  "filter_main_maxthon": {
    "Image
| endswith": "\\maxthon.exe"
  },
  "filter_main_edge_1": [
    {
      "Image
| startswith": "C:\\Program Files (x86)\\Microsoft\\EdgeWebView\\Application\\"
    },
    {
      "Image
| endswith": "\\WindowsApps\\MicrosoftEdge.exe"
    },
    {
      "Image": [
        "C:\\Program Files (x86)\\Microsoft\\Edge\\Application\\msedge.exe",
        "C:\\Program Files\\Microsoft\\Edge\\Application\\msedge.exe"
      ]
    }
  ],
  "filter_main_edge_2": {
    "Image
| startswith": [
      "C:\\Program Files (x86)\\Microsoft\\EdgeCore\\",
      "C:\\Program Files\\Microsoft\\EdgeCore\\"
    ],
    "Image
| endswith": [
      "\\msedge.exe",
      "\\msedgewebview2.exe"
    ]
  },
  "filter_main_opera": {
    "Image
| endswith": "\\opera.exe"
  },
  "filter_main_safari": {
    "Image
| endswith": "\\safari.exe"
  },
  "filter_main_seamonkey": {
    "Image
| endswith": "\\seamonkey.exe"
  },
  "filter_main_vivaldi": {
    "Image
| endswith": "\\vivaldi.exe"
  },
  "filter_main_whale": {
    "Image
| endswith": "\\whale.exe"
  },
  "condition": "network_connection and (selection and not 1 of filter_main_*)"
}

False Positives

  • Legitimate applications communicating with the Telegram API e.g. web browsers not in the exclusion list, app with an RSS etc.

Field Validations

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