From 051df9047628ba35e9fab447f9513cae01c11f6d Mon Sep 17 00:00:00 2001 From: Jonathan Leitschuh Date: Thu, 8 Sep 2022 21:45:33 +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 --- jbake-core/src/main/java/org/jbake/app/ZipUtil.java | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/jbake-core/src/main/java/org/jbake/app/ZipUtil.java b/jbake-core/src/main/java/org/jbake/app/ZipUtil.java index 481b94a10..8b94c4e56 100644 --- a/jbake-core/src/main/java/org/jbake/app/ZipUtil.java +++ b/jbake-core/src/main/java/org/jbake/app/ZipUtil.java @@ -28,7 +28,10 @@ public static void extract(InputStream is, File outputFolder) throws IOException byte[] buffer = new byte[1024]; while ((entry = zis.getNextEntry()) != null) { - File outputFile = new File(outputFolder.getCanonicalPath() + File.separatorChar + entry.getName()); + File outputFile = new File(outputFolder.getCanonicalPath(), entry.getName()); + if (!outputFile.toPath().normalize().startsWith(outputFolder.getCanonicalPath())) { + throw new IOException("Bad zip entry"); + } File outputParent = new File(outputFile.getParent()); outputParent.mkdirs();