Command Injection in nginx

1) Command Injection

EUVDB-ID: #VU40985

Risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2014-3556

CWE-ID: CWE-77 - Command injection

Exploit availability: No

Description

The vulnerability allows a remote non-authenticated attacker to gain access to sensitive information.

The STARTTLS implementation in mail/ngx_mail_smtp_handler.c in the SMTP proxy in nginx 1.5.x and 1.6.x before 1.6.1 and 1.7.x before 1.7.4 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.

Mitigation

Install update from vendor's website.

Vulnerable software versions

nginx: 1.5.0 - 1.7.3

External links

http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html
http://marc.info/?l=bugtraq&m=142103967620673&w=2
http://nginx.org/download/patch.2014.starttls.txt
http://bugzilla.redhat.com/show_bug.cgi?id=1126891

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.