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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'
- Rule type
- Scheduled
- Version
- 1.0.3
- Query frequency
- 12h
- Query period
- 12h
- Trigger
- gt 0
Declared MITRE coverage
Declared sources
Metadata from the source file. No dependencies inferred from KQL.
Connectors
Data types
KQL query
Original query, unchanged.
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])
Declared entities
Source provenance
GitHubDisplayed values come from files in Azure/Azure-Sentinel. They describe the published template, not your workspace configuration.
- Commit
9800e51↗- Source identifier
968358d6-6af8-49bb-aaa4-187b3067fb95
Additional source files 1
Detections/W3CIISLog/ProxyShellPwn2Own.yamlsource ↗GSTEP / CATALOG TRACKING
Added to catalog : 16 Sept 2026 · 05:49 UTC
Last change observed : 16 Sept 2026 · 05:49 UTC