SB2017071121 - Multiple vulnerabilities in Microsoft Exchange Server

Description

This security bulletin contains information about 3 vulnerabilities.

1) Open redirect (CVE-ID: CVE-2017-8621)

CWE-ID: CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a remote attacker to redirect website visitors to external websites.

The weakness exists due to incorrect handling of open redirect requests by Microsoft Exchange. A remote attacker can create a specially crafted link, redirect the victim on potentially dangerous website and gain access to potentially sensitive information.

Successful exploitation of the vulnerability may result in information disclosure.

2) Cross-site scripting (CVE-ID: CVE-2017-8560)

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability is caused by incorrect filtration of input data by Microsoft Exchange Outlook Web Access (OWA). A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in victim’s browser in security context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

3) Cross-site scripting (CVE-ID: CVE-2017-8559)

CWE-ID: CWE-79 - Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:U/U:Clear

The disclosed vulnerability allows a remote attacker to perform cross-site scripting (XSS) attacks.

The vulnerability is caused by incorrect filtration of input data by Microsoft Exchange Outlook Web Access (OWA). A remote attacker can trick the victim to follow a specially crafted link and execute arbitrary HTML and script code in victim’s browser in security context of vulnerable website.

Successful exploitation of this vulnerability may allow a remote attacker to steal potentially sensitive information, change appearance of the web page, perform phishing and drive-by-download attacks.

Remediation

Install update from vendor's website.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-8621
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-8560
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2017-8559