#VU15841 Man-in-the-middle attack in Microsoft Exchange Server - CVE-2018-8581

Vulnerability identifier: #VU15841

Vulnerability risk: Low

CVSSv4.0: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Clear]

CVE-ID: CVE-2018-8581

CWE-ID: CWE-300

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 gain elevated privileges on the target system.

The vulnerability exists due to use of a registry key exists called HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlLsa and lack of loopback check. A remote unauthenticated attacker can conduct a man-in-the-middle attack to forward an authentication request to a Microsoft Exchange Server, thereby allowing impersonation of another Exchange user and gain SYSTEM privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2010, 2013 RTM 15.00.0516.032, 2016 RTM 15.01.0225.042, 2019 RTM 15.02.0221.012

---

External links
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8581

---

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?

Yes. This vulnerability is being exploited in the wild.