Microsoft security software 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:

  • JDK and JRE 7 Update 4 and earlier Java SE

  • JDK and JRE 6 Update 32 and earlier Java SE

  • JDK and JRE 5.0 Update 35 and earlier Java SE

  • SDK and JRE 1.4.2_37 and earlier Java SE

To check if you're running a vulnerable version of Java:

  1. In Control Panel, double-click Programs.
  2. If Java is installed you will see it in the list of installed programs. Click it to open the Java Control Panel.
  3. On the General tab, click About to see which version of Java you have installed.

You might 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.

What to do now

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.

Update Java

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:

Get more help

You can also visit our advanced troubleshooting page or search the Microsoft virus and malware community for more help.

If you’re using Windows XP, see our Windows XP end of support page.

Threat behavior

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.

What is an exploit?

Exploits are written to take advantage of weaknesses (or vulnerabilities) in legitimate software. A project called Common Vulnerabilities and Exposures (CVE) gives each vulnerability a unique number, in this case "CVE-2012-1723". The portion "2012" refers to the year the vulnerability was discovered, and "1723" is a unique ID for this specific vulnerability. You can find more information on the CVE website.


Downloads and installs files

If you visit a website containing the malicious code while using a vulnerable version of Java, Exploit:Java/CVE-2012-1723 is loaded. It then attempts to download and run files from a remote host/URL, including other malware.

Additional technical details

Exploit:Java/CVE-2012-1723 uses a bug in the field access code inside of the Java Runtime Environment. The issue is in the optimization performed when a field inside the class is accessed. A static field with a ClassLoader or Object type and bunch of instance-fields with custom data type is a strong indication of exploitation. A bunch of instance-fields are a buffer area where a type-confused object is retrieved. After retrieving the ClassLoader instance using type-confusion, the exploit takes these privileges and can then run outside of the sandbox.

Exploit:Java/CVE-2012-1723 attacks the security model instead of memory corruption issues. With memory corruption issues, the exploit is dependent on the specific CPU (Central Processing Unit) type and operating systems, and might be affected by mitigation technology like DEP (Data Execution Prevention) or ASLR (Address Space Layout Randomization).

Attacking the security model means that the exploit might be effective on any platform the Java interpreter is on; for example Windows, MacOS, Linux, etc.

Usually the 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 Environment. Since it is usually found in every JAR, it won't be listed.

Below are some examples of files that exploit the vulnerability described in CVE-2012-1723:

  • 1fadb1943260992ba9ae75a0d651bf6b5b5d8b39
    • bet3b5326b236b326a.class
    • bet3b5326b236b326b.class
    • bet3b5326b236b326c.class
    • bet3b5326b236b326d.class
    • bet3b5326b236b326e.class
    • bet3b5326b236b326f.clas
  • 2cd0734ce557dd18d3104b367a9a84df1fe9dcb3
    • Abanli.class
    • Ati.class
    • Fonnt.class
    • Grebok.class
    • Ini.class
    • Inttos.class
    • Olya.class
    • Sara.class
    • Shashlik.class
    • Third.class
  • 37ba6cf857bd5f22c26a1e05c5ec7fd19fb40d79
    • CreateClassAndExec.class
    • DownloadExec.class
    • main.class
    • UnsafeUtil.class
  • 3bce21eb8df8c8b3fc4b7f46fcbaa222efa6badf
    • hit.class
    • pom.class
    • string.class
    • weirMattesBus.class
  • 8281b17676dc99f7856588bbd7fbb0f0124dd062
    • main.class
    • w.class
    • x.class
    • y.class
    • z.class
  • 4290441b2edc07c606ffb3b6407c6b7df99413f3
    • fbeatbeb.class
    • fbeatbec.class
    • fbeatbed.class
    • fbeatbee.class
    • fbeatbef.class
  • 4eb928ec636e7fbd5736f8edbc20e18e89d24076
    • bet3b5326b236b326a.class
    • bet3b5326b236b326b.class
    • bet3b5326b236b326c.class
    • bet3b5326b236b326d.class
    • bet3b5326b236b326e.class
    • bet3b5326b236b326f.class
  • 5590352bfd98395e27da3543374491f8c729d10a
    • Ati.class
    • Atyans.class
    • Faiibt.class
    • Ini.class
    • Luihbg.class
    • Nata.class
    • Ponos.class
    • Sara.class
    • Shashlik.class
    • Third.class
  • 8d258823317be9e09b046fb11753d105c9d5861f
    • greateGamb.class
    • greateGamc.class
    • greateGamd.class
    • greateGame.class
    • greateGamf.class
  • 94c61b0eb8f4cc8b0f8708267155bfdd3f5da51e
    • Fire.class
    • FireX.class
    • Fuck.class
    • sikinti.class
    • ters.class
  • addbe7741ab30a209d526b5da1022310a5b33f60
    • ACL.class
    • Cry.class
    • ET.class
    • ILikeIt.class
    • TVSD$PT.class
    • TVSD.class
    • Utils.class
  • bd026427600dec5622f5602db2ebac93dda67802
    • Fdskjfudsfqiqqi.class
    • kalibton.class
    • prototipe.class
    • Qdsfwefw.class
    • Sfjkgherilg.class
    • XqxQxqX.class
    • ZOOIIUUPP.class
  • c81d30a6e7ffd7de97a1d008a95740592bf5947e
    • b4a.class
    • b4b.class
    • b4c.class
    • b4d.class
    • b4e.class
    • b4f.class
  • ef082c683717465817b4a718f6975fae5850e3c3
    • Epay.class
    • ClLoader.class
    • Clmaker.class
    • News.class
  • f1dd728b1ac2117e835541e8fa32e06b1b817995
    • plugindetecta.class
    • plugindetectb.class
    • plugindetectc.class
    • plugindetectd.class
    • plugindetecte.class
    • plugindetectf.class

Once the exploit obtains full privileges on your PC, it might:

  • Run an executable file (that might be detected as malware) included in the JAR
  • Run an executable file (that might be detected as malware) from a URL hard-coded in the exploit's file
  • Take instructions from the HTML file (such as a URL to the malware executable) that loaded them
Related information / Related references

The articles referenced below outline some of the the technical details of the weakness this vulnerability exploits:

Analysis by Jeong Wook (Matt) Oh


Alerts from your security software might be the only symptom.


Alert level: Severe
This entry was first published on: Jul 31, 2012
This entry was updated on: Oct 29, 2014

This threat is also detected as:
No known aliases