GHSA-mjmj-j48q-9wg2

Suggest an improvement
Source
https://github.com/advisories/GHSA-mjmj-j48q-9wg2
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2022/12/GHSA-mjmj-j48q-9wg2/GHSA-mjmj-j48q-9wg2.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-mjmj-j48q-9wg2
Aliases
Related
Published
2022-12-12T21:19:47Z
Modified
2024-09-11T06:13:44.808862Z
Severity
  • 8.3 (High) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:L CVSS Calculator
Summary
SnakeYaml Constructor Deserialization Remote Code Execution
Details

Summary

SnakeYaml's Constructor class, which inherits from SafeConstructor, allows any type be deserialized given the following line:

new Yaml(new Constructor(TestDataClass.class)).load(yamlContent);

Types do not have to match the types of properties in the target class. A ConstructorException is thrown, but only after a malicious payload is deserialized.

Severity

High, lack of type checks during deserialization allows remote code execution.

Proof of Concept

Execute bash run.sh. The PoC uses Constructor to deserialize a payload for RCE. RCE is demonstrated by using a payload which performs a http request to http://127.0.0.1:8000.

Example output of successful run of proof of concept:

$ bash run.sh

[+] Downloading snakeyaml if needed
[+] Starting mock HTTP server on 127.0.0.1:8000 to demonstrate RCE
nc: no process found
[+] Compiling and running Proof of Concept, which a payload that sends a HTTP request to mock web server.
[+] An exception is expected.
Exception:
Cannot create property=payload for JavaBean=Main$TestDataClass@3cbbc1e0
 in 'string', line 1, column 1:
    payload: !!javax.script.ScriptEn ... 
    ^
Can not set java.lang.String field Main$TestDataClass.payload to javax.script.ScriptEngineManager
 in 'string', line 1, column 10:
    payload: !!javax.script.ScriptEngineManag ... 
             ^

    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:291)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:172)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:332)
    at org.yaml.snakeyaml.constructor.BaseConstructor.constructObjectNoCheck(BaseConstructor.java:230)
    at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:220)
    at org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:174)
    at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:158)
    at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:491)
    at org.yaml.snakeyaml.Yaml.load(Yaml.java:416)
    at Main.main(Main.java:37)
Caused by: java.lang.IllegalArgumentException: Can not set java.lang.String field Main$TestDataClass.payload to javax.script.ScriptEngineManager
    at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at java.base/jdk.internal.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
    at java.base/jdk.internal.reflect.UnsafeObjectFieldAccessorImpl.set(UnsafeObjectFieldAccessorImpl.java:81)
    at java.base/java.lang.reflect.Field.set(Field.java:780)
    at org.yaml.snakeyaml.introspector.FieldProperty.set(FieldProperty.java:44)
    at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:286)
    ... 9 more
[+] Dumping Received HTTP Request. Will not be empty if PoC worked
GET /proof-of-concept HTTP/1.1
User-Agent: Java/11.0.14
Host: localhost:8000
Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2
Connection: keep-alive

Further Analysis

Potential mitigations include, leveraging SnakeYaml's SafeConstructor while parsing untrusted content.

See https://bitbucket.org/snakeyaml/snakeyaml/issues/561/cve-2022-1471-vulnerability-in#comment-64581479 for discussion on the subject.

A fix was released in version 2.0. See https://bitbucket.org/snakeyaml/snakeyaml/issues/561/cve-2022-1471-vulnerability-in#comment-64876314 for more information.

Timeline

Date reported: 4/11/2022 Date fixed: Date disclosed: 10/13/2022

References

Affected packages

Maven / org.yaml:snakeyaml

Package

Name
org.yaml:snakeyaml
View open source insights on deps.dev
Purl
pkg:maven/org.yaml/snakeyaml

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
2.0

Affected versions

1.*

1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14
1.15
1.16
1.17
1.18
1.19
1.20
1.21
1.22
1.23
1.24
1.25
1.26
1.27
1.28
1.29
1.30
1.31
1.32
1.33

Database specific

{
    "last_known_affected_version_range": "<= 1.33"
}