CVE-2020-8595
Description
An unauthorized access vulnerability was found in Istio in the servicemesh-proxy. An attacker can use this flaw to specify an HTTP path and gain unauthorized access, even if the path is configured to only be accessed with a valid JSON Web Token (JWT).
Mitigation
Depending on the paths used in the exact match clause, it is possible to update the path to a regex.
As provided by the Istio Product Committee, the following mitigation can be employed.
The original policy specifying a JWT protected path is as follows:
---
apiVersion: "authentication.istio.io/v1alpha1"
kind: "Policy"
metadata:
name: "jwt-example"
namespace: istio-system
spec:
targets:
- name: istio-ingressgateway
origins:
- jwt:
issuer: "testing@secure.istio.io"
jwksUri: "https://raw.githubusercontent.com/istio/istio/release-1.4/security/tools/jwt/samples/jwks.json";
trigger_rules:
- included_paths:
- exact: /productpage
The exact path definition can then be updated to a regular expression:
---
- jwt:
issuer: "testing@secure.istio.io"
jwksUri: "https://raw.githubusercontent.com/istio/istio/release-1.4/security/tools/jwt/samples/jwks.json";
trigger_rules:
- included_paths:
- regex: '/productpage(\?.*)?'
- regex: '/productpage(#.*)?'
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.3 | 7.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | Low | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | Low | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data; Read Files or Directories
An attacker could read sensitive data, either by reading the data directly from a data store that is not properly restricted, or by accessing insufficiently-protected, privileged functionality to read the data.
Integrity
Technical Impact: Modify Application Data; Modify Files or Directories
An attacker could modify sensitive data, either by writing the data directly to a data store that is not properly restricted, or by accessing insufficiently-protected, privileged functionality to write the data.
Access Control
Technical Impact: Gain Privileges or Assume Identity; Execute Unauthorized Code or Commands
When access control checks are not applied consistently - or not at all - an attacker could gain privileges and execute unauthorized code or commands by modifying or reading critical data directly, or by accessing insufficiently-protected, privileged functionality.
Acknowledgements
Red Hat would like to thank The Istio Product Security Committee for reporting this issue.
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