From 4ced9757a62ba166a29e50e56138301f908d55bd Mon Sep 17 00:00:00 2001 From: Jonathan Leitschuh Date: Fri, 29 Jul 2022 19:17:18 +0000 Subject: [PATCH] vuln-fix: Zip Slip Vulnerability This fixes a Zip-Slip vulnerability. This change does one of two things. This change either 1. Inserts a guard to protect against Zip Slip. OR 2. Replaces `dir.getCanonicalPath().startsWith(parent.getCanonicalPath())`, which is vulnerable to partial path traversal attacks, with the more secure `dir.getCanonicalFile().toPath().startsWith(parent.getCanonicalFile().toPath())`. For number 2, 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`. Weakness: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') Severity: High CVSSS: 7.4 Detection: CodeQL (https://codeql.github.com/codeql-query-help/java/java-zipslip/) & OpenRewrite (https://public.moderne.io/recipes/org.openrewrite.java.security.ZipSlip) Reported-by: Jonathan Leitschuh Signed-off-by: Jonathan Leitschuh Bug-tracker: https://github.com/JLLeitschuh/security-research/issues/16 Co-authored-by: Moderne --- src/main/java/utilities/UnZip.java | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/src/main/java/utilities/UnZip.java b/src/main/java/utilities/UnZip.java index fffa481..2014a9f 100644 --- a/src/main/java/utilities/UnZip.java +++ b/src/main/java/utilities/UnZip.java @@ -19,7 +19,10 @@ public static void unZip(String zippedFile, String outputFolder) { ze = zis.getNextEntry(); while (ze != null) { String fileName = ze.getName(); - File newFile = new File(outputFolder + File.separator + fileName); + File newFile = new File(outputFolder, fileName); + if (!newFile.toPath().normalize().startsWith(outputFolder)) { + throw new RuntimeException("Bad zip entry"); + } System.out.println("file unzip : " + newFile.getAbsoluteFile()); //create all non exists folders //else you will hit FileNotFoundException for compressed folder