Discord CDN Risky File Download
Id | 010bd98c-a6be-498c-bdcd-502308c0fdae |
Rulename | Discord CDN Risky File Download |
Description | Identifies callouts to Discord CDN addresses for risky file extensions. This detection will trigger when a callout for a risky file is made to a discord server that has only been seen once in your environment. Unique discord servers are identified using the server ID that is included in the request URL (DiscordServerId in query). Discord CDN has been used in multiple campaigns to download additional payloads |
Severity | Medium |
Tactics | CommandAndControl |
Techniques | T1071.001 |
Required data connectors | CefAma |
Kind | Scheduled |
Query frequency | 1d |
Query period | 1d |
Trigger threshold | 0 |
Trigger operator | gt |
Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Zscaler Internet Access/Analytic Rules/DiscordCDNRiskyDownload.yaml |
Version | 1.0.4 |
Arm template | 010bd98c-a6be-498c-bdcd-502308c0fdae.json |
let connectionThreshold = 1;
let riskyExtensions = dynamic([".bin",".exe",".dll",".bin",".msi"]);
CommonSecurityLog
| where DeviceVendor =~ "ZScaler"
| where RequestURL has_any("media.discordapp.net", "cdn.discordapp.com")
| where RequestURL has "attachments"
| where DeviceAction !~ "blocked"
| extend DiscordServerId = extract(@"\/attachments\/([0-9]+)\/", 1, RequestURL)
| summarize dcount(RequestURL), make_set(SourceUserName), make_set(SourceIP), make_set(RequestURL), min(TimeGenerated), max(TimeGenerated), make_set(DeviceAction) by DiscordServerId, DeviceProduct
| where dcount_RequestURL <= connectionThreshold
| mv-expand set_SourceUserName to typeof(string), set_RequestURL to typeof(string), set_DeviceAction to typeof(string), set_SourceIP to typeof(string)
| summarize by DiscordServerId, DeviceProduct, dcount_RequestURL, set_SourceUserName, min_TimeGenerated, max_TimeGenerated, set_DeviceAction, set_SourceIP, set_RequestURL
| project StartTime=min_TimeGenerated, EndTime=max_TimeGenerated, DeviceActionTaken=set_DeviceAction, DeviceProduct, SourceUser=set_SourceUserName, SourceIP=set_SourceIP, RequestURL=set_RequestURL
| where RequestURL has_any (riskyExtensions)
triggerOperator: gt
entityMappings:
- entityType: Account
fieldMappings:
- identifier: FullName
columnName: SourceUser
- entityType: IP
fieldMappings:
- identifier: Address
columnName: SourceIP
- entityType: URL
fieldMappings:
- identifier: Url
columnName: RequestURL
description: |
'Identifies callouts to Discord CDN addresses for risky file extensions. This detection will trigger when a callout for a risky file is made to a discord server that has only been seen once in your environment. Unique discord servers are identified using the server ID that is included in the request URL (DiscordServerId in query). Discord CDN has been used in multiple campaigns to download additional payloads'
queryFrequency: 1d
severity: Medium
queryPeriod: 1d
id: 010bd98c-a6be-498c-bdcd-502308c0fdae
version: 1.0.4
triggerThreshold: 0
relevantTechniques:
- T1071.001
status: Available
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Zscaler Internet Access/Analytic Rules/DiscordCDNRiskyDownload.yaml
query: |
let connectionThreshold = 1;
let riskyExtensions = dynamic([".bin",".exe",".dll",".bin",".msi"]);
CommonSecurityLog
| where DeviceVendor =~ "ZScaler"
| where RequestURL has_any("media.discordapp.net", "cdn.discordapp.com")
| where RequestURL has "attachments"
| where DeviceAction !~ "blocked"
| extend DiscordServerId = extract(@"\/attachments\/([0-9]+)\/", 1, RequestURL)
| summarize dcount(RequestURL), make_set(SourceUserName), make_set(SourceIP), make_set(RequestURL), min(TimeGenerated), max(TimeGenerated), make_set(DeviceAction) by DiscordServerId, DeviceProduct
| where dcount_RequestURL <= connectionThreshold
| mv-expand set_SourceUserName to typeof(string), set_RequestURL to typeof(string), set_DeviceAction to typeof(string), set_SourceIP to typeof(string)
| summarize by DiscordServerId, DeviceProduct, dcount_RequestURL, set_SourceUserName, min_TimeGenerated, max_TimeGenerated, set_DeviceAction, set_SourceIP, set_RequestURL
| project StartTime=min_TimeGenerated, EndTime=max_TimeGenerated, DeviceActionTaken=set_DeviceAction, DeviceProduct, SourceUser=set_SourceUserName, SourceIP=set_SourceIP, RequestURL=set_RequestURL
| where RequestURL has_any (riskyExtensions)
tactics:
- CommandAndControl
name: Discord CDN Risky File Download
tags:
- Discord
kind: Scheduled
requiredDataConnectors:
- dataTypes:
- CommonSecurityLog
connectorId: CefAma
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"apiVersion": "2024-01-01-preview",
"id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/010bd98c-a6be-498c-bdcd-502308c0fdae')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/010bd98c-a6be-498c-bdcd-502308c0fdae')]",
"properties": {
"alertRuleTemplateName": "010bd98c-a6be-498c-bdcd-502308c0fdae",
"customDetails": null,
"description": "'Identifies callouts to Discord CDN addresses for risky file extensions. This detection will trigger when a callout for a risky file is made to a discord server that has only been seen once in your environment. Unique discord servers are identified using the server ID that is included in the request URL (DiscordServerId in query). Discord CDN has been used in multiple campaigns to download additional payloads'\n",
"displayName": "Discord CDN Risky File Download",
"enabled": true,
"entityMappings": [
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "SourceUser",
"identifier": "FullName"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "SourceIP",
"identifier": "Address"
}
]
},
{
"entityType": "URL",
"fieldMappings": [
{
"columnName": "RequestURL",
"identifier": "Url"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Zscaler Internet Access/Analytic Rules/DiscordCDNRiskyDownload.yaml",
"query": "let connectionThreshold = 1;\nlet riskyExtensions = dynamic([\".bin\",\".exe\",\".dll\",\".bin\",\".msi\"]);\nCommonSecurityLog\n| where DeviceVendor =~ \"ZScaler\"\n| where RequestURL has_any(\"media.discordapp.net\", \"cdn.discordapp.com\")\n| where RequestURL has \"attachments\"\n| where DeviceAction !~ \"blocked\"\n| extend DiscordServerId = extract(@\"\\/attachments\\/([0-9]+)\\/\", 1, RequestURL)\n| summarize dcount(RequestURL), make_set(SourceUserName), make_set(SourceIP), make_set(RequestURL), min(TimeGenerated), max(TimeGenerated), make_set(DeviceAction) by DiscordServerId, DeviceProduct\n| where dcount_RequestURL <= connectionThreshold\n| mv-expand set_SourceUserName to typeof(string), set_RequestURL to typeof(string), set_DeviceAction to typeof(string), set_SourceIP to typeof(string)\n| summarize by DiscordServerId, DeviceProduct, dcount_RequestURL, set_SourceUserName, min_TimeGenerated, max_TimeGenerated, set_DeviceAction, set_SourceIP, set_RequestURL\n| project StartTime=min_TimeGenerated, EndTime=max_TimeGenerated, DeviceActionTaken=set_DeviceAction, DeviceProduct, SourceUser=set_SourceUserName, SourceIP=set_SourceIP, RequestURL=set_RequestURL\n| where RequestURL has_any (riskyExtensions)\n",
"queryFrequency": "P1D",
"queryPeriod": "P1D",
"severity": "Medium",
"status": "Available",
"subTechniques": [
"T1071.001"
],
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"CommandAndControl"
],
"tags": [
"Discord"
],
"techniques": [
"T1071"
],
"templateVersion": "1.0.4",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}