Exchange SSRF Autodiscover ProxyShell - Detection
| Id | 968358d6-6af8-49bb-aaa4-187b3067fb95 |
| Rulename | Exchange SSRF Autodiscover ProxyShell - Detection |
| Description | This query looks for suspicious request patterns to Exchange servers that fit patterns recently blogged about by PeterJson. This exploitation chain utilises an SSRF vulnerability in Exchange which eventually allows the attacker to execute arbitrary Powershell on the server. In the example powershell can be used to write an email to disk with an encoded attachment containing a shell. Reference: https://peterjson.medium.com/reproducing-the-proxyshell-pwn2own-exploit-49743a4ea9a1 |
| Severity | High |
| Tactics | InitialAccess |
| Techniques | T1190 |
| Required data connectors | AzureMonitor(IIS) |
| Kind | Scheduled |
| Query frequency | 12h |
| Query period | 12h |
| Trigger threshold | 0 |
| Trigger operator | gt |
| Source Uri | https://github.com/Azure/Azure-Sentinel/blob/master/Detections/W3CIISLog/ProxyShellPwn2Own.yaml |
| Version | 1.0.2 |
| Arm template | 968358d6-6af8-49bb-aaa4-187b3067fb95.json |
let successCodes = dynamic([200, 302, 401]);
W3CIISLog
| where scStatus has_any (successCodes)
| where ipv4_is_private(cIP) == False
| where csUriStem hasprefix "/autodiscover/autodiscover.json"
| project TimeGenerated, cIP, sIP, sSiteName, csUriStem, csUriQuery, Computer, csUserName, _ResourceId, FileUri
| where (csUriQuery !has "Protocol" and isnotempty(csUriQuery))
or (csUriQuery has_any("/mapi/", "powershell"))
or (csUriQuery contains "@" and csUriQuery matches regex @"\.[a-zA-Z]{2,4}?(?:[a-zA-Z]{2,4}\/)")
or (csUriQuery contains ":" and csUriQuery matches regex @"\:[0-9]{2,4}\/")
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(csUserName, "@")[0]), AccountUPNSuffix = tostring(split(csUserName, "@")[1])
triggerOperator: gt
queryFrequency: 12h
description: |
'This query looks for suspicious request patterns to Exchange servers that fit patterns recently
blogged about by PeterJson. This exploitation chain utilises an SSRF vulnerability in Exchange
which eventually allows the attacker to execute arbitrary Powershell on the server. In the example
powershell can be used to write an email to disk with an encoded attachment containing a shell.
Reference: https://peterjson.medium.com/reproducing-the-proxyshell-pwn2own-exploit-49743a4ea9a1'
version: 1.0.2
kind: Scheduled
triggerThreshold: 0
requiredDataConnectors:
- connectorId: AzureMonitor(IIS)
dataTypes:
- W3CIISLog
queryPeriod: 12h
name: Exchange SSRF Autodiscover ProxyShell - Detection
OriginalUri: https://github.com/Azure/Azure-Sentinel/blob/master/Detections/W3CIISLog/ProxyShellPwn2Own.yaml
id: 968358d6-6af8-49bb-aaa4-187b3067fb95
tactics:
- InitialAccess
metadata:
source:
kind: Community
author:
name: Thomas McElroy
categories:
domains:
- Security - Others
support:
tier: Community
relevantTechniques:
- T1190
severity: High
entityMappings:
- fieldMappings:
- identifier: FullName
columnName: csUserName
- identifier: Name
columnName: AccountName
- identifier: UPNSuffix
columnName: AccountUPNSuffix
entityType: Account
- fieldMappings:
- identifier: FullName
columnName: Computer
entityType: Host
- fieldMappings:
- identifier: Address
columnName: cIP
entityType: IP
- fieldMappings:
- identifier: ResourceId
columnName: _ResourceId
entityType: AzureResource
query: |
let successCodes = dynamic([200, 302, 401]);
W3CIISLog
| where scStatus has_any (successCodes)
| where ipv4_is_private(cIP) == False
| where csUriStem hasprefix "/autodiscover/autodiscover.json"
| project TimeGenerated, cIP, sIP, sSiteName, csUriStem, csUriQuery, Computer, csUserName, _ResourceId, FileUri
| where (csUriQuery !has "Protocol" and isnotempty(csUriQuery))
or (csUriQuery has_any("/mapi/", "powershell"))
or (csUriQuery contains "@" and csUriQuery matches regex @"\.[a-zA-Z]{2,4}?(?:[a-zA-Z]{2,4}\/)")
or (csUriQuery contains ":" and csUriQuery matches regex @"\:[0-9]{2,4}\/")
| extend HostName = tostring(split(Computer, ".")[0]), DomainIndex = toint(indexof(Computer, '.'))
| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)
| extend AccountName = tostring(split(csUserName, "@")[0]), AccountUPNSuffix = tostring(split(csUserName, "@")[1])
{
"$schema": "https://schema.management.azure.com/schemas/2019-04-01/deploymentTemplate.json#",
"contentVersion": "1.0.0.0",
"parameters": {
"workspace": {
"type": "String"
}
},
"resources": [
{
"apiVersion": "2023-02-01-preview",
"id": "[concat(resourceId('Microsoft.OperationalInsights/workspaces/providers', parameters('workspace'), 'Microsoft.SecurityInsights'),'/alertRules/968358d6-6af8-49bb-aaa4-187b3067fb95')]",
"kind": "Scheduled",
"name": "[concat(parameters('workspace'),'/Microsoft.SecurityInsights/968358d6-6af8-49bb-aaa4-187b3067fb95')]",
"properties": {
"alertRuleTemplateName": "968358d6-6af8-49bb-aaa4-187b3067fb95",
"customDetails": null,
"description": "'This query looks for suspicious request patterns to Exchange servers that fit patterns recently\nblogged about by PeterJson. This exploitation chain utilises an SSRF vulnerability in Exchange\nwhich eventually allows the attacker to execute arbitrary Powershell on the server. In the example\npowershell can be used to write an email to disk with an encoded attachment containing a shell.\nReference: https://peterjson.medium.com/reproducing-the-proxyshell-pwn2own-exploit-49743a4ea9a1'\n",
"displayName": "Exchange SSRF Autodiscover ProxyShell - Detection",
"enabled": true,
"entityMappings": [
{
"entityType": "Account",
"fieldMappings": [
{
"columnName": "csUserName",
"identifier": "FullName"
},
{
"columnName": "AccountName",
"identifier": "Name"
},
{
"columnName": "AccountUPNSuffix",
"identifier": "UPNSuffix"
}
]
},
{
"entityType": "Host",
"fieldMappings": [
{
"columnName": "Computer",
"identifier": "FullName"
}
]
},
{
"entityType": "IP",
"fieldMappings": [
{
"columnName": "cIP",
"identifier": "Address"
}
]
},
{
"entityType": "AzureResource",
"fieldMappings": [
{
"columnName": "_ResourceId",
"identifier": "ResourceId"
}
]
}
],
"OriginalUri": "https://github.com/Azure/Azure-Sentinel/blob/master/Detections/W3CIISLog/ProxyShellPwn2Own.yaml",
"query": "let successCodes = dynamic([200, 302, 401]);\nW3CIISLog\n| where scStatus has_any (successCodes)\n| where ipv4_is_private(cIP) == False\n| where csUriStem hasprefix \"/autodiscover/autodiscover.json\"\n| project TimeGenerated, cIP, sIP, sSiteName, csUriStem, csUriQuery, Computer, csUserName, _ResourceId, FileUri\n| where (csUriQuery !has \"Protocol\" and isnotempty(csUriQuery))\nor (csUriQuery has_any(\"/mapi/\", \"powershell\"))\nor (csUriQuery contains \"@\" and csUriQuery matches regex @\"\\.[a-zA-Z]{2,4}?(?:[a-zA-Z]{2,4}\\/)\")\nor (csUriQuery contains \":\" and csUriQuery matches regex @\"\\:[0-9]{2,4}\\/\")\n| extend HostName = tostring(split(Computer, \".\")[0]), DomainIndex = toint(indexof(Computer, '.'))\n| extend HostNameDomain = iff(DomainIndex != -1, substring(Computer, DomainIndex + 1), Computer)\n| extend AccountName = tostring(split(csUserName, \"@\")[0]), AccountUPNSuffix = tostring(split(csUserName, \"@\")[1])\n",
"queryFrequency": "PT12H",
"queryPeriod": "PT12H",
"severity": "High",
"suppressionDuration": "PT1H",
"suppressionEnabled": false,
"tactics": [
"InitialAccess"
],
"techniques": [
"T1190"
],
"templateVersion": "1.0.2",
"triggerOperator": "GreaterThan",
"triggerThreshold": 0
},
"type": "Microsoft.OperationalInsights/workspaces/providers/alertRules"
}
]
}