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
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for (ZipEntry ze; (ze = zipIn.getNextEntry()) != null; ) { |
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String path = Path.of(Utilities.path(targetDir, ze.getName())).normalize().toFile().getAbsolutePath(); |
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if (!path.startsWith(targetDir)) { |
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// see: https://snyk.io/research/zip-slip-vulnerability |
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throw new RuntimeException("Entry with an illegal path: " + ze.getName()); |
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} |
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
JLLeitschuh Reporter
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
TerminologyCacheManagercache 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
/outnotis not under the/outdirectory.It's important to understand that the terminating slash may be removed when using various
Stringrepresentations of theFileobject.For example, on Linux,
println(new File("/var"))will print/var, butprintln(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#startsWithwill adequately protect againts this vulnerability.For example:
file.getCanonicalFile().toPath().startsWith(BASE_DIRECTORY)orfile.getCanonicalFile().toPath().startsWith(BASE_DIRECTORY_FILE.getCanonicalFile().toPath())Other Examples
Vulnerability
org.hl7.fhir.core/org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/terminologies/TerminologyCacheManager.java
Lines 99 to 105 in b0daf66
While
getAbsolutePathwill return a normalized path, because the stringpathis 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