CVE-2017-7525
Description
A deserialization flaw was discovered in the jackson-databind which could allow an unauthenticated user to perform code execution by sending the maliciously crafted input to the readValue method of the ObjectMapper.
Statement
This issue affects the versions of jackson-databind (in Satellite 6.0 and 6.1) and candlepin (which embeds a copy of jackson-databind in Satellite 6.2) as shipped with Red Hat Satellite 6.x. However the affected code is NOT used at this time:
Candlepin currently uses the default type resolution configuration for the ObjectMappers it creates/uses. Nowhere in candlepin do we enable global polymorphic deserialization via enableDefaultTyping(...), therefore based on the documentation sited BZ 1462702 , candlepin should not be affected.
However as the vulnerable software ships with the product we have marked them as vulnerable to ensure the issue is tracked.
JBoss EAP 7.x only uses the vulnerable Jackson Databind library for marshalling and unmarshalling of JSON objects passed to JAX-RS webservices. Some advise about how to remain safe when using JAX-RS webservices on JBoss EAP 7.x is available here:
https://access.redhat.com/solutions/3279231
Although JBoss Fuse ships the vulnerable version of jackson-databind, it does not call on enableDefaultTyping() for any polymorphic deserialization operations which is the root cause of this vulnerability. We have raised a Jira tracker to ensure that jackson-databind will be upgraded for Fuse 7.0, however due to feasibility issues jackson-databind cannot be upgraded in JBoss Fuse 6.3.
Mitigation
Mitigation to this problem is to not trigger polymorphic desrialization globally by using: objectMapper.enableDefaultTyping() and rather use @JsonTypeInfo on the class property to explicitly define the type information. For more information on this issue please refer to https://www.github.com/mbechler/marshalsec/blob/master/marshalsec.pdf?raw=true
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 | 8.1 | 9.8 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | High | High | N/A |
| Integrity Impact | High | High | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart; DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory)
An attacker could provide unexpected values and cause a program crash or arbitrary control of resource allocation, leading to excessive consumption of resources such as memory and CPU.
Confidentiality
Technical Impact: Read Memory; Read Files or Directories
An attacker could read confidential data if they are able to control resource references.
Integrity,Confidentiality,Availability
Technical Impact: Modify Memory; Execute Unauthorized Code or Commands
An attacker could use malicious input to modify data or possibly alter control flow in unexpected ways, including arbitrary command execution.
Acknowledgements
Red Hat would like to thank Liao Xinxi (NSFOCUS) for reporting this issue.
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