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Security Advisories: GSA_kwCzR0hTQS05NjU0LXByNGYtZ2g2bc4AAyDc

HL7 FHIR Partial Path Zip Slip due to bypass of CVE-2023-24057

Impact

Zip Slip protections implemented in CVE-2023-24057 (GHSA-jqh6-9574-5x22) can be bypassed due a partial path traversal vulnerability.

This issue allows a malicious actor to potentially break out of the TerminologyCacheManager cache directory. The impact is limited to sibling directories.

To demonstrate the vulnerability, consider userControlled.getCanonicalPath().startsWith("/usr/out") will allow an attacker to access a directory with a name like /usr/outnot.

Why?

To demonstrate this vulnerability, consider "/usr/outnot".startsWith("/usr/out").
The check is bypassed although /outnot is not under the /out directory.
It's important to understand that the terminating slash may be removed when using various String representations of the File object.
For example, on Linux, println(new File("/var")) will print /var, but println(new File("/var", "/") will print /var/;
however, println(new File("/var", "/").getCanonicalPath()) will print /var.

The Fix

Comparing paths with the java.nio.files.Path#startsWith will adequately protect againts this vulnerability.

For example: file.getCanonicalFile().toPath().startsWith(BASE_DIRECTORY) or file.getCanonicalFile().toPath().startsWith(BASE_DIRECTORY_FILE.getCanonicalFile().toPath())

Other Examples

Vulnerability

https://github.com/hapifhir/org.hl7.fhir.core/blob/b0daf666725fa14476d147522155af1e81922aac/org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/terminologies/TerminologyCacheManager.java#L99-L105

While getAbsolutePath will return a normalized path, because the string path is not slash terminated, the guard can be bypassed to write the contents of the Zip file to a sibling directory of the cache directory.

Patches

All org.hl7.fhir.core libraries should be updated to 5.6.106.

Workarounds

Unknown

References

Permalink: https://github.com/advisories/GHSA-9654-pr4f-gh6m
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS05NjU0LXByNGYtZ2g2bc4AAyDc
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: 12 months ago
Updated: 3 months ago


CVSS Score: 7.5
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Identifiers: GHSA-9654-pr4f-gh6m, CVE-2023-28465
References:

Affected Packages

maven:ca.uhn.hapi.fhir:org.hl7.fhir.validation
Versions: < 5.6.106
Fixed in: 5.6.106
maven:ca.uhn.hapi.fhir:org.hl7.fhir.utilities
Versions: < 5.6.106
Fixed in: 5.6.106
maven:ca.uhn.hapi.fhir:org.hl7.fhir.r5
Versions: < 5.6.106
Fixed in: 5.6.106
maven:ca.uhn.hapi.fhir:org.hl7.fhir.r4b
Versions: < 5.6.106
Fixed in: 5.6.106
maven:ca.uhn.hapi.fhir:org.hl7.fhir.convertors
Versions: < 5.6.106
Fixed in: 5.6.106
maven:ca.uhn.hapi.fhir:org.hl7.fhir.core
Versions: < 5.6.106
Fixed in: 5.6.106