Published:2019/02/28  Last Updated:2019/02/28

JVN#79543573
The installer of Microsoft Teams may insecurely load Dynamic Link Libraries

Overview

The installer of Microsoft Teams may insecurely load Dynamic Link Libraries.

Products Affected

  • Microsoft Teams

Description

The installer of Microsoft Teams contains an issue with the DLL search path, which may lead to insecurely loading Dynamic Link Libraries (CWE-427).
Microsoft states that the root cause of this vulnerability is "Application Directory (App Dir) DLL planting", thus there is no plan to release any security updates to address this issue.

For details, refer to "Application Directory (App Dir) DLL planting" released by Microsoft.

Impact

Arbitrary code may be executed with the privilege of the user invoking the installer.

Solution

Apply Workaround
Applying the following workarounds may mitigate the impacts of this vulnerability.

  • Save the installer into a newly created directory, and confirm there are no unrelated files in the directory then invoke the installer.
  • Make sure there are no suspicious files in the directory where the installer is saved.
  • If your organization uses shared directories to place installers for organizational operations, make sure that the shared directory is set read-only for non-administrative users.

Vendor Status

Vendor Status Last Update Vendor Notes
Microsoft Japan Co.,Ltd. Vulnerable 2019/02/28

References

  1. Japan Vulnerability Notes JVNTA#91240916
    Insecure DLL Loading and Command Execution Issues on Many Windows Application Programs

JPCERT/CC Addendum

Vulnerability Analysis by JPCERT/CC

CVSS v3 CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Base Score: 7.8
Attack Vector(AV) Physical (P) Local (L) Adjacent (A) Network (N)
Attack Complexity(AC) High (H) Low (L)
Privileges Required(PR) High (H) Low (L) None (N)
User Interaction(UI) Required (R) None (N)
Scope(S) Unchanged (U) Changed (C)
Confidentiality Impact(C) None (N) Low (L) High (H)
Integrity Impact(I) None (N) Low (L) High (H)
Availability Impact(A) None (N) Low (L) High (H)
CVSS v2 AV:N/AC:M/Au:N/C:P/I:P/A:P
Base Score: 6.8
Access Vector(AV) Local (L) Adjacent Network (A) Network (N)
Access Complexity(AC) High (H) Medium (M) Low (L)
Authentication(Au) Multiple (M) Single (S) None (N)
Confidentiality Impact(C) None (N) Partial (P) Complete (C)
Integrity Impact(I) None (N) Partial (P) Complete (C)
Availability Impact(A) None (N) Partial (P) Complete (C)

Comment

This analysis assumes that the user is tricked into placing a malicious DLL file prepared by an attacker in a specific folder.

Credit

Asuka Nakajima of NTT Secure Platform Laboratories reported this vulnerability to IPA.
JPCERT/CC coordinated with the developer under Information Security Early Warning Partnership.

Other Information

JPCERT Alert
JPCERT Reports
CERT Advisory
CPNI Advisory
TRnotes
CVE CVE-2019-5922
JVN iPedia JVNDB-2019-000014