Vulnerability identifier: #VU8291

Vulnerability risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-11761

CWE-ID: CWE-200

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Microsoft Exchange Server
Server applications / Mail servers

Vendor: Microsoft

Description

The vulnerability allows a remote attacker to obtain potentially sensitive information.

The vulnerability exists due to improper input sanitization issue in Microsoft Exchange. A remote attacker can send Calendar-related messages containing specially crafted tags to an Exchange server, trick the victim into observing telemetry from these requests and discerning properties of internal hosts intended to be hidden from the Internet, and identify the existence of RFC1918 addresses on the local network from a client on the Internet.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Service Pack 1 15.00.0847.032 - 2013 Cumulative Update 17 15.00.1320.004, 2016 Cumulative Update 5 15.01.0845.034 - 2016 Cumulative Update 6 15.01.1034.026

---

External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-11761

---

Q & A

Can this vulnerability be exploited remotely?

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

Is there known malware, which exploits this vulnerability?

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