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)
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Solutions/Zscaler Internet Access/Analytic Rules/DiscordCDNRiskyDownload.yaml
tags:
- Discord
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
requiredDataConnectors:
- dataTypes:
- CommonSecurityLog
connectorId: CefAma
name: Discord CDN Risky File Download
triggerThreshold: 0
tactics:
- CommandAndControl
version: 1.0.4
relevantTechniques:
- T1071.001
triggerOperator: gt
entityMappings:
- entityType: Account
fieldMappings:
- columnName: SourceUser
identifier: FullName
- entityType: IP
fieldMappings:
- columnName: SourceIP
identifier: Address
- entityType: URL
fieldMappings:
- columnName: RequestURL
identifier: Url
id: 010bd98c-a6be-498c-bdcd-502308c0fdae
status: Available
kind: Scheduled
queryFrequency: 1d
queryPeriod: 1d
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)
{
"$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"
}
]
}