Asken App for Android fails to restrict custom URL schemes properly


Asken App for Android by asken Inc. provides the function to access a requested URL using Custom URL Scheme. The App does not restrict access to the function properly (CWE-939) which may be exploited to direct the App to access any sites.
CVSS Severity (What is CVSS?)

CVSS V3 Severity:
Base Metrics 4.3 (Medium) [IPA Score]
  • Attack Vector: Network
  • Attack Complexity: Low
  • Privileges Required: None
  • User Interaction: Required
  • Scope: Unchanged
  • Confidentiality Impact: None
  • Integrity Impact: Low
  • Availability Impact: None
CVSS V2 Severity:
Base Metrics 4.3 (Medium) [IPA Score]
  • Access Vector: Network
  • Access Complexity: Medium
  • Authentication: None
  • Confidentiality Impact: None
  • Integrity Impact: Partial
  • Availability Impact: None
Affected Products

asken Inc.
  • asken for Android versions from v.3.0.0 to v.4.2.x

Note that Asken App is only available in Japan.

A remote attacker may lead a user to access an arbitrary website via the vulnerable App. As a result, the user may become a victim of a phishing attack.

[Update the Application]
Update the application to the latest version according to the information provided by the developer.
Vendor Information

asken Inc.
CWE (What is CWE?)

  1. Permissions(CWE-264) [IPA Evaluation]
CVE (What is CVE?)

  1. CVE-2021-20733

  1. JVN : JVN#38034268
Revision History

  • [2021/06/14]
      Web page was published