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 <[email protected]>
Signed-off-by: Jonathan Leitschuh <[email protected]>

Bug-tracker: JLLeitschuh/security-research#16


Co-authored-by: Moderne <[email protected]>

src/main/java/cn/springmvc/mybatis/common/utils/ZipUtil.java

@@ -33,7 +33,7 @@ public static boolean compress(List<File> files, String zipPath, boolean isDel)
         }
         try {
             // ----压缩文件：
-            FileOutputStream stream = new FileOutputStream(zipPath);
+            FileOutputStream stream = new FileOutputStream(new File(zipPath));
             CheckedOutputStream checkedStream = new CheckedOutputStream(stream, new CRC32());// 使用指定校验和创建输出流
             ZipOutputStream zipStream = new ZipOutputStream(checkedStream);
             BufferedOutputStream out = new BufferedOutputStream(zipStream);
@@ -98,7 +98,11 @@ public static void unZipFiles(File zipfile, String descDir) {
                 entry = ((ZipEntry) entries.nextElement());
                 zipEntryName = entry.getName();
                 in = zf.getInputStream(entry);
-                out = new FileOutputStream(descDir + zipEntryName);
+                final File zipEntryFile = new File(descDir, zipEntryName);
+                if (!zipEntryFile.toPath().normalize().startsWith(descDir)) {
+                    throw new RuntimeException("Bad zip entry");
+                }
+                out = new FileOutputStream(zipEntryFile);
                 buf1 = new byte[1024];
                 len = 0;
                 while ((len = in.read(buf1)) > 0) {