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vuln-fix: Partial Path Traversal Vulnerability
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This fixes a partial path traversal vulnerability.

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())`.

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`.

Weakness: CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Severity: Medium
CVSSS: 6.1
Detection: CodeQL & OpenRewrite (https://public.moderne.io/recipes/org.openrewrite.java.security.PartialPathTraversalVulnerability)

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

Bug-tracker: JLLeitschuh/security-research#13

Co-authored-by: Moderne <[email protected]>
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JLLeitschuh and TeamModerne committed Sep 21, 2022
1 parent 46a7059 commit 40670ec
Showing 1 changed file with 1 addition and 1 deletion.
Original file line number Diff line number Diff line change
Expand Up @@ -313,7 +313,7 @@ private void updateFilesAndFolders() throws Exception {
Thread.currentThread().interrupt();
throw new InterruptedException("APKTool thread was aborted abnormally!");
}
if (!iteratorNewPackage.getCanonicalPath().startsWith(iteratorOldPackage.getCanonicalPath())) {
if (!iteratorNewPackage.getCanonicalFile().toPath().startsWith(iteratorOldPackage.getCanonicalFile().toPath())) {
LOGGER.info("---> moving from " + iteratorOldPackage.getPath() + " >>>>>> " + iteratorNewPackage.getPath());
if (iteratorOldPackage.exists()) {
FileComputingManager.getInstance().
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