cbcvebase.
CVE-2022-41082
published 2022-10-03

CVE-2022-41082: Microsoft Exchange Server Remote Code Execution Vulnerability

PriorityP194high8CVSS 3.1
AVAACLPRLUINSUCHIHAH
KEVITWEXPLOITRansomwareInitial access
CISA Known Exploited Vulnerabilitydue 2022-10-21
Exploited in the wild
EPSS
99.97%
100.0th percentile
Microsoft Exchange Server Remote Code Execution Vulnerability

Affected

13 ranges
VendorProductVersion rangeFixed in
microsoftexchange_server
microsoftexchange_server
microsoftexchange_server
microsoftmicrosoft_exchange_server_2013_cumulative_update_23>= 15.00.0 < 15.00.1497.04415.00.1497.044
microsoftmicrosoft_exchange_server_2016_cumulative_update_22>= 15.0.0 < 15.01.2375.03715.01.2375.037
microsoftmicrosoft_exchange_server_2016_cumulative_update_23>= 15.01.0 < 15.01.2507.01615.01.2507.016
microsoftmicrosoft_exchange_server_2019_cumulative_update_11>= 15.02.0 < 15.02.0986.03615.02.0986.036
microsoftmicrosoft_exchange_server_2019_cumulative_update_12>= 15.02.0 < 15.02.1118.02015.02.1118.020
msrcmicrosoft_exchange_server_2013_cumulative_update_23
msrcmicrosoft_exchange_server_2016_cumulative_update_22
msrcmicrosoft_exchange_server_2016_cumulative_update_23
msrcmicrosoft_exchange_server_2019_cumulative_update_11
msrcmicrosoft_exchange_server_2019_cumulative_update_12

Detection & IOCsextracted from sources · hover to see the quote

ip45.76.141.84
ip45.76.143.143
ip179.60.149.28
ip104.244.79.6
ip185.220.101.182
ip137.184.67.33
ip103.9.76.208
urlhttps://{exchange_host}/owa/{email_address}/powershell
pathC:\Program Files\Microsoft\Exchange Server\V15\Logging\CmdletInfra\Powershell-Proxy\Http\
commandGet-ChildItem -Recurse -Path -Filter "*.log" | Select-String -Pattern 'powershell.*autodiscover\.json.*\@.*200'
port8080
other(?=.*autodiscover)(?=.*powershell)
processcertutil.exe
sigma
filter event_type = ENUM.PROCESS and actor_process_image_name = "w3wp.exe" and (action_process_image_command_line contains "&ipconfig&echo" or action_process_image_command_line contains "&quesr&echo" or action_process_image_command_line contains "&whoami&echo" or action_process_image_command_line contains "&c:&echo" or action_process_image_command_line contains "&cd&echo" or action_process_image_command_line contains "&echo [E]" or action_process_image_command_line contains "&echo [S]")
sigma
filter event_type = ENUM.FILE and actor_process_image_name = "w3wp.exe" and action_file_path contains "FrontEnd\HttpProxy" and actor_process_command_line contains "MSExchange"
  • Detect China Chopper webshell activity by monitoring for w3wp.exe spawning processes with command lines containing China Chopper marker strings such as &ipconfig&echo, &whoami&echo, &echo [E], &echo [S]
  • Detect suspicious file writes in Exchange FrontEnd\HttpProxy directories by w3wp.exe processes with MSExchange in the command line
  • Detect post-exploit certutil connections to public IPs on port 8080 — filter out RFC1918 private address space
  • Detect DLL and EXE writes to C:\Users\Public\ on Exchange hosts (where w3wp.exe is present) as a post-exploitation indicator
  • Search IIS logs for exploitation evidence using the PowerShell pattern matching autodiscover.json with powershell and HTTP 200 responses
  • OWASSRF exploit targets the OWA /owa/{email}/powershell endpoint directly, bypassing the autodiscover-based URL rewrite mitigation for ProxyNotShell; requests made through OWA rather than Autodiscover endpoint
  • The existing ProxyNotShell URL rewrite mitigation regex (?=.*autodiscover)(?=.*powershell) does NOT block OWASSRF since OWASSRF uses the OWA endpoint instead of Autodiscover
  • Monitor Exchange Remote PowerShell logs at C:\Program Files\Microsoft\Exchange Server\V15\Logging\CmdletInfra\Powershell-Proxy\Http\ for signs of exploitation
  • Post-exploitation tools observed include Plink, AnyDesk, BITSadmin, Mimikatz, AdFind, and ConnectWise ScreenConnect; monitor for these on Exchange servers
  • Play ransomware group used OWASSRF (CVE-2022-41080 + CVE-2022-41082) for initial access via OWA; monitor for PowerShell spawned by IIS w3wp.exe as execution indicator
  • Track ProxyNotShell scanning activity in GreyNoise using tag 'Exchange ProxyNotShell Vuln Check' or GNQL query: cve:CVE-2022-41040 OR cve:CVE-2022-41082
  • ·The ProxyNotShell URL rewrite mitigation (blocking requests matching autodiscover+powershell) is NOT effective against the OWASSRF exploit method, which routes directly through the OWA endpoint
  • ·CVE-2022-41082 exploitation requires authenticated access (standard user credentials sufficient); the authentication bar is low given widespread credential theft
  • ·Affected versions are Exchange Server 2013, 2016, and 2019 before KB5019758; Exchange Online customers are already protected and need no action
  • ·Ensure X-Forwarded-For header is configured to log true external IP addresses for requests to proxied Exchange services, otherwise attacker IPs may not be visible in logs

CVSS provenance

nvdv3.18.0HIGHCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vulncheck8.8HIGH
cisa9.8CRITICAL
vendor_msrc8.0HIGH
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