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Overview

com.google.guava:guava is a set of core libraries that includes new collection types (such as multimap and multiset,immutable collections, a graph library, functional types, an in-memory cache and more.

Affected versions of this package are vulnerable to Creation of Temporary File in Directory with Insecure Permissions due to the use of Java's default temporary directory for file creation in FileBackedOutputStream. Other users and apps on the machine with access to the default Java temporary directory can access the files created by this class. This more fully addresses the underlying issue described in CVE-2020-8908, by deprecating the permissive temp file creation behavior.

NOTE: Even though the security vulnerability is fixed in version 32.0.0, the maintainers recommend using version 32.0.1, as version 32.0.0 breaks some functionality under Windows.

Remediation

Upgrade com.google.guava:guava to version 32.0.0-android, 32.0.0-jre or higher.

References

• GitHub Commit
• GitHub Issue
• GitHub Issue
• GitHub Release

Overview

com.google.guava:guava is a set of core libraries that includes new collection types (such as multimap and multiset,immutable collections, a graph library, functional types, an in-memory cache and more.

Affected versions of this package are vulnerable to Information Disclosure. The file permissions on the file created by com.google.common.io.Files.createTempDir allow an attacker running a malicious program co-resident on the same machine to steal secrets stored in this directory. This is because, by default, on unix-like operating systems the /tmp directory is shared between all users, so if the correct file permissions aren't set by the directory/file creator, the file becomes readable by all other users on that system.

PoC

File guavaTempDir = com.google.common.io.Files.createTempDir();
System.out.println("Guava Temp Dir: " + guavaTempDir.getName());
runLS(guavaTempDir.getParentFile(), guavaTempDir); // Prints the file permissions -> drwxr-xr-x
File child = new File(guavaTempDir, "guava-child.txt");
child.createNewFile();
runLS(guavaTempDir, child); // Prints the file permissions -> -rw-r--r--

For Android developers, choosing a temporary directory API provided by Android is recommended, such as context.getCacheDir(). For other Java developers, we recommend migrating to the Java 7 API java.nio.file.Files.createTempDirectory() which explicitly configures permissions of 700, or configuring the Java runtime's java.io.tmpdir system property to point to a location whose permissions are appropriately configured.

Remediation

There is no fix for com.google.guava:guava. However, in version 30.0 and above, the vulnerable functionality has been deprecated. In oder to mitigate this vulnerability, upgrade to version 30.0 or higher and ensure your dependencies don't use the createTempDir or createTempFile methods.

References

• GitHub Commit

• GitHub Commit

• GitHub Issue

Overview

org.jetbrains.kotlin:kotlin-stdlib is a Kotlin Standard Library for JVM.

Affected versions of this package are vulnerable to Information Exposure. A Kotlin application using createTempDir or createTempFile and placing sensitive information within either of these locations would be leaking this information in a read-only way to other users also on this system.

Note: As of version 1.4.21, the vulnerable functions have been marked as deprecated. Due to still being usable, this advisory is kept as "unfixed".

PoC by JLLeitschuh

package org.jlleitschuh.sandbox

import org.junit.jupiter.api.Test
import java.io.BufferedReader
import java.io.File
import java.io.IOException
import java.io.InputStreamReader
import java.nio.file.Files

class KotlinTempDirectoryPermissionCheck {
    @Test
    fun `kotlin check default directory permissions`() {
        val dir = createTempDir()
        runLS(dir.parentFile, dir) // Prints drwxr-xr-x
    }

    @Test
    fun `Files check default directory permissions`() {
        val dir = Files.createTempDirectory("random-directory")
        runLS(dir.toFile().parentFile, dir.toFile()) // Prints drwx------
    }

    @Test
    fun `kotlin check default file permissions`() {
        val file = createTempFile()
        runLS(file.parentFile, file) // Prints -rw-r--r--
    }

    @Test
    fun `Files check default file permissions`() {
        val file = Files.createTempFile("random-file", ".txt")
        runLS(file.toFile().parentFile, file.toFile()) // Prints -rw-------
    }

    private fun runLS(file: File, lookingFor: File) {
        val processBuilder = ProcessBuilder()
        processBuilder.command("ls", "-l", file.absolutePath)
        try {
            val process = processBuilder.start()
            val output = StringBuilder()
            val reader = BufferedReader(
                InputStreamReader(process.inputStream)
            )
            reader.lines().forEach { line ->
                if (line.contains("total")) {
                    output.append(line).append('\n')
                }
                if (line.contains(lookingFor.name)) {
                    output.append(line).append('\n')
                }
            }
            val exitVal = process.waitFor()
            if (exitVal == 0) {
                println("Success!")
                println(output)
            } else {
                //abnormal...
            }
        } catch (e: IOException) {
            e.printStackTrace()
        } catch (e: InterruptedException) {
            e.printStackTrace()
        }
    }
}

Remediation

Upgrade org.jetbrains.kotlin:kotlin-stdlib to version 2.1.0 or higher.

References

• Documentation
• GitHub Commit
• Issue
• Vulnerable Code #1
• Vulnerable Code #2