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Insecure digital certificates

Description

The apk certificate was signed using the SHA1 algorithm. This algorithm is considered quite insecure, so it should not be used to sign certificates since it can be reversed in order to obtain the signing key. On the other hand, there are URLs that, just by accessing them, it is possible to download the digital certificates stored in them, thus exposing confidential information of the organization.

Impact

  • Obtain the signing key of the applications certificate.
  • Change the application in the appStore to a malicious one by using the obtained signing keys.

Recommendation

Sign the certificate with SHA2 or higher.

Threat

Anonymous attacker from the Internet.

Expected Remediation Time

⌚ 15 minutes.

Score

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base

  • Attack vector: N
  • Attack complexity: H
  • Privileges required: N
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: L
  • Availability: N

Temporal

  • Exploit code madurity: P
  • Remediation level: O
  • Report confidence: X

Result

  • Vector string: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N/E:P/RL:O/RC:X
  • Score:
    • Base: 4.8
    • Temporal: 4.3
  • Severity:
    • Base: Medium
    • Temporal: Medium

Code Examples

Compliant code

The application has a secure algorithm for the certificate signature

android {
signingConfigs {
getByName("config") {
keyAlgorithm = keystoreProperties["SHA2"]
...
}
}
}

Non compliant code

The application has an insecure algorithm for the certificate signature

android {
signingConfigs {
getByName("config") {
keyAlgorithm = keystoreProperties["SHA1"]
...
}
}
}

Requirements