CVE-2017-15095
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. This issue extends the previous flaw CVE-2017-7525 by blacklisting more classes that could be used maliciously.
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:
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)
Access Control
Technical Impact: Bypass Protection Mechanism
Attackers may be able to find other malicious inputs that were not expected by the developer, allowing them to bypass the intended protection mechanism.
Acknowledgements
Red Hat would like to thank Liao Xinxi (NSFOCUS) for reporting this issue.
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