Multiple vulnerabilities in Microsoft Exchange Server



Published: 2021-05-11 | Updated: 2021-09-12
Risk High
Patch available YES
Number of vulnerabilities 4
CVE-ID CVE-2021-31209
CVE-2021-31207
CVE-2021-31198
CVE-2021-31195
CWE-ID CWE-354
CWE-254
CWE-94
Exploitation vector Network
Public exploit Vulnerability #2 is being exploited in the wild.
Public exploit code for vulnerability #4 is available.
Vulnerable software
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Microsoft Exchange Server
Server applications / Mail servers

Vendor Microsoft

Security Bulletin

This security bulletin contains information about 4 vulnerabilities.

Updated: 01.06.2021

Updated vulnerability #1.

1) Improper validation of integrity check value

EUVDB-ID: #VU53082

Risk: Medium

CVSSv3.1: 5.2 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-31209

CWE-ID: CWE-354 - Improper Validation of Integrity Check Value

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass integrity checks.

The vulnerability exists within the handling of Exchange Server Help updates. A remote attacker on the local network can bypass integrity check on update downloads.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 23, 2016 Cumulative Update 19, 2016 Cumulative Update 20, 2019 Cumulative Update 8, 2019 Cumulative Update 9

CPE2.3 External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31209
http://www.zerodayinitiative.com/advisories/ZDI-21-615/

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.

2) Security features bypass

EUVDB-ID: #VU53085

Risk: Low

CVSSv3.1: 5.8 [CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-31207

CWE-ID: CWE-254 - Security Features

Exploit availability: Yes

Description

The vulnerability allows a remote user to bypass authentication process.

The vulnerability exists due to security feature bypass issue in Microsoft Exchange Server. A remote administrator can gain full access to target system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 23, 2016 Cumulative Update 19, 2016 Cumulative Update 20, 2019 Cumulative Update 8, 2019 Cumulative Update 9

CPE2.3 External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31207

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user 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.

3) Code Injection

EUVDB-ID: #VU53084

Risk: High

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-31198

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

Exploit availability: No

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation in Microsoft Exchange Server. A remote attacker can execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 23, 2016 Cumulative Update 19, 2016 Cumulative Update 20, 2019 Cumulative Update 8, 2019 Cumulative Update 9

CPE2.3 External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31198

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.

4) Code Injection

EUVDB-ID: #VU53083

Risk: High

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-31195

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation in Microsoft Exchange Server. A remote attacker can execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 23, 2016 Cumulative Update 19, 2016 Cumulative Update 20, 2019 Cumulative Update 8, 2019 Cumulative Update 9

CPE2.3 External links

http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31195

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.



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