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Alert level: Severe Detected with Windows Defender Antivirus
Also detected as: No associated aliases
Windows Defender detects and removes this threat.
This threat uses a Java vulnerability to download and run files on your PC, including other malware.
It runs when you visit a hacked or malicious website and you have a vulnerable version of Java.
The following versions of Java are vulnerable:
- Java Development Kit and Java Runtime Environment 7 Update 10 and earlier
To check if you're running a vulnerable version of Java:
- In Control Panel, double-click Programs.
- If Java is installed you will see it in the list of installed programs. Click it to open the Java Control Panel.
- On the General tab, click About to see which version of Java you have installed.
You may get an alert about this threat even if you're not using a vulnerable version of Java. This is because we detect when a website tries to use the vulnerability, even if it isn't successful.
Use the following free Microsoft software to detect and remove this threat:
You should also run a full scan. A full scan might find other, hidden malware.
Make sure you install all available Java updates. You can read more about this vulnerability and download software updates from these links:
You should remove older versions of Java, as keeping old and unsupported versions of Java on your PC is a serious security risk:
If you continue to get alerted about this threat, deleting your temporary Java files can help:
It's also important to keep your other software up to date:
Clear the cache
You should delete your temporary Internet files so your security software doesn't continue to detect this threat:
Get more help
You can also see our advanced troubleshooting page for more help.
If you’re using Windows XP, see our Windows XP end of support page.
Exploit:Java/CVE-2013-0422 is a malicious Java applet that tries to exploit a vulnerability (CVE-2013-0422) in Oracle JRE 7.
Threat in context
Java is a general-purpose programming language, but cases of this exploit are targeted against the Java plug-in for web browsers. The intent of the Java plug-in is that Java programs (or "applets") can be offered by websites, and run in a "sandbox" where the Java plug-in enforces rules on what the Java applet can do so that it cannot escape restricted environment.
The first malware to exploit this vulnerability was found in December 2012 in the wild, and publicly disclosed in January 2013. It is exploiting a package restriction issue in JRE(Java Runtime Environment). The malware uses a typical Java exploitation technique by loading its malicious payload class in a trusted code area, which makes privilege escalation possible. The payload can be embedded in the JAR (Java Archive) file, or it may be downloaded from the Internet. The payload can be any kind of malware that the attacker wants to deliver to your PC.
What is an exploit?
Exploits are written to take advantage of weaknesses (or vulnerabilities) in legitimate software. A project called Common Vulnerabilities and Exposures (or CVE) is used by many vendors and organizations and gives each vulnerability a unique number, in this case "CVE-2013-0422". The portion "2013" refers to the year the vulnerability was discovered, and "0422" is a unique identifier. There is more information on the Common Vulnerabilities and Exposures website.
Additional technical details
Exploit:Java/CVE-2013-0422 is a Java malware that uses a security vulnerability from JRE 7. The problem occurs with the java.lang.invoke.MethodHandle package in JRE 7. MethodHandle is a new feature introduced with JRE 7. It gives developers more convenience and flexibility with dynamic language use in Java. With this advantage, there is also a glitch with the security check when MethodHandle is used to resolve classes from the MethodHandle package itself. Specifically, you can create MethodHandle for the java.lang.invoke.MethodHandles.Lookup class and it will bypass security checks when you try to use findConstructor method through this handle.
This vulnerability is a logic error in checking package access when the caller is coming from specific package and the method has specific names. The exploitation doesn’t rely on specific memory layout, which means the exploits are usually portable across multiple platforms, except the fact that the major portion of payload we observed are targeting Windows operating systems.
Usually exploits are written using a few Java classes working together. The various class files are bundled into an archive called a JAR, which uses the ZIP file format. Every JAR contains a Manifest.MF file to identify itself to the Java Runtime. Since it is found in every JAR, it won't be listed.
Below are some examples of files that exploit the vulnerability described in CVE-2013-0422:
Once the exploit has full privileges on your PC, it can:
- Run an executable file (that may be detected as malware) included in the JAR
- Run an executable file (that may be detected as malware) from a URL hardcoded in the exploit's file
- Take instructions from the HTML file (like a URL to the malware executable) that loaded them
Analysis by Jeong Wook (Matt) Oh
Alerts from your security software may be the only symptom.