CVE-2020-5411
Description
From CVE.org
When configured to enable default typing, Jackson contained a deserialization vulnerability that could lead to arbitrary code execution. Jackson fixed this vulnerability by blacklisting known "deserialization gadgets". Spring Batch configures Jackson with global default typing enabled which means that through the previous exploit, arbitrary code could be executed if all of the following is true: * Spring Batch's Jackson support is being leveraged to serialize a job's ExecutionContext. * A malicious user gains write access to the data store used by the JobRepository (where the data to be deserialized is stored). In order to protect against this type of attack, Jackson prevents a set of untrusted gadget classes from being deserialized. Spring Batch should be proactive against blocking unknown "deserialization gadgets" when enabling default typing.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | 8.1 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | High | High | 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:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
A successful exploit of this vulnerability requires the use of jackson deserialization by the server, which is beyond the attacker's control, and additionally, an attacker would have to insert malicious data in the data store, which at the least would require a successful login or some additional exploit.
We feel that these conditions are better reflected with an AC:H scoring rather than AC:L, which would bring the score to 8.1, and an impact of Important rather than Critical.
Understanding the Weakness (CWE)
Integrity
Technical Impact: Modify Application Data; Unexpected State
Attackers can modify unexpected objects or data that was assumed to be safe from modification. Deserialized data or code could be modified without using the provided accessor functions, or unexpected functions could be invoked.
Availability
Technical Impact: DoS: Resource Consumption (CPU)
If a function is making an assumption on when to terminate, based on a sentry in a string, it could easily never terminate.
Other
Technical Impact: Varies by Context
The consequences can vary widely, because it depends on which objects or methods are being deserialized, and how they are used. Making an assumption that the code in the deserialized object is valid is dangerous and can enable exploitation. One example is attackers using gadget chains to perform unauthorized actions, such as generating a shell.
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