From 2252ceb20cfcf5963a483328bc93955b60221e3f Mon Sep 17 00:00:00 2001 From: Jonathan Leitschuh Date: Mon, 3 Oct 2022 21:30:17 +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 --- core/src/main/java/com/threerings/getdown/tools/Patcher.java | 3 +++ core/src/main/java/com/threerings/getdown/util/FileUtil.java | 3 +++ 2 files changed, 6 insertions(+) diff --git a/core/src/main/java/com/threerings/getdown/tools/Patcher.java b/core/src/main/java/com/threerings/getdown/tools/Patcher.java index 5c8baaaa..cad69314 100644 --- a/core/src/main/java/com/threerings/getdown/tools/Patcher.java +++ b/core/src/main/java/com/threerings/getdown/tools/Patcher.java @@ -125,6 +125,9 @@ protected void patchFile (ZipFile file, ZipEntry entry, File appdir, String path { File target = new File(appdir, path); File patch = new File(appdir, entry.getName()); + if (!patch.toPath().normalize().startsWith(appdir.toPath().normalize())) { + throw new RuntimeException("Bad zip entry"); + } File otarget = new File(appdir, path + ".old"); JarDiffPatcher patcher = null; diff --git a/core/src/main/java/com/threerings/getdown/util/FileUtil.java b/core/src/main/java/com/threerings/getdown/util/FileUtil.java index f7c67ef1..8f75b7c7 100644 --- a/core/src/main/java/com/threerings/getdown/util/FileUtil.java +++ b/core/src/main/java/com/threerings/getdown/util/FileUtil.java @@ -136,6 +136,9 @@ public static void unpackJar (ZipFile jar, File target, boolean cleanExistingDir while (entries.hasMoreElements()) { ZipEntry entry = entries.nextElement(); File efile = new File(target, entry.getName()); + if (!efile.toPath().normalize().startsWith(target.toPath().normalize())) { + throw new IOException("Bad zip entry"); + } // if we're unpacking a normal jar file, it will have special path // entries that allow us to create our directories first