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GHSA-cm59-pr5q-cw85
No affected components available
spring-boot versions prior to version v2.2.11.RELEASE was vulnerable to temporary directory hijacking. This vulnerability impacted the org.springframework.boot.web.server.AbstractConfigurableWebServerFactory.createTempDir method.
The vulnerable method is used to create a work directory for embedded web servers such as Tomcat and Jetty. The directory contains configuration files, JSP/class files, etc. If a local attacker got the permission to write in this directory, they could completely take over the application (ie. local privilege escalation).
Impact Location
This vulnerability impacted the following source location:
/**
* Return the absolute temp dir for given web server.
* @param prefix server name
* @return the temp dir for given server.
*/
protected final File createTempDir(String prefix) {
try {
File tempDir = File.createTempFile(prefix + ".", "." + getPort());
tempDir.delete();
tempDir.mkdir();
tempDir.deleteOnExit();
return tempDir;
}
- https://github.com/spring-projects/spring-boot/blob/ce70e7d768977242a8ea6f93188388f273be5851/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/server/AbstractConfigurableWebServerFactory.java#L165-L177
This vulnerability exists because File.mkdir returns false when it fails to create a directory, it does not throw an exception. As such, the following race condition exists:
File tmpDir =File.createTempFile(prefix + ".", "." + getPort()); // Attacker knows the full path of the file that will be generated
// delete the file that was created
tmpDir.delete(); // Attacker sees file is deleted and begins a race to create their own directory before Jetty.
// and make a directory of the same name
// SECURITY VULNERABILITY: Race Condition! - Attacker beats java code and now owns this directory
tmpDir.mkdirs(); // This method returns 'false' because it was unable to create the directory. No exception is thrown.
// Attacker can write any new files to this directory that they wish.
// Attacker can read any files created by this process.
Prerequisites
This vulnerability impacts Unix-like systems, and very old versions of Mac OSX and Windows as they all share the system temporary directory between all users.
Patches
This vulnerability was inadvertently fixed as a part of this patch: https://github.com/spring-projects/spring-boot/commit/667ccdae84822072f9ea1a27ed5c77964c71002d
This vulnerability is patched in versions v2.2.11.RELEASE or later.
Workarounds
Setting the java.io.tmpdir system environment variable to a directory that is exclusively owned by the executing user will fix this vulnerability for all operating systems.
The vulnerability requires local access to the device to be exploited. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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