Exploit:Java/CVE-2013-1493

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-2013-1493". The part "2013" refers to the year the vulnerability was discovered, and "1493" is a unique ID for this specific vulnerability. You can find more information on the CVE website.

Payload

Downloads and installs files

If you visit a website containing the malicious code while using a vulnerable version of Java, Exploit:Java/CVE-2013-1493 is loaded. It then tries to download and run files from a remote host/URL, including other malware.

Additional technical details

Exploit:Java/CVE-2013-1493 first appeared in February 2013 as a 0-day which didn't have any patches available, as described in the FireEye blog YAJ0: Yet Another Java Zero-Day. Oracle later released an advisory for this vulnerability. The problem lies in memory management and involved a memory corruption vulnerability and memory contents leak issue with a color management class.

The first samples in the wild were using a memory corruption issue found in color management code and used heap-spraying techniques. They also used leaked memory information to locate the accurate memory base location for exploitation.

As the malware evolved, it used obfuscation methods to hide its intention, like obfuscated string and code structures.

This exploit might be effective on any platform the Java interpreter is on; for example Windows, MacOS, Linux, and so on. At the time of analysis, we have only observed the exploit targeting Windows.

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. Since it is found in every JAR, it won't be listed.

The following are some examples of files that exploit the vulnerability described in CVE-2013-1493:

• In sample ad62df685c00ad42a5f731bb8206cef0b064035f
• ImAlphaLeak.class
• ImAlphaMyBufferedImage.class
• ImAlphaMyColorSpace.class
• ImAlpha.class
• svchost.cf
• In sample 5a02a3eb6354afc6cff661d258cdbd52ca84b805
• Artmil.class
• Art.class
• br.class
• bs.class
• eu.class
• fh.class
• gt.class
• n7.class
• n8.class
• n9.class
• na.class
• nb.class
• nc.class
• nd.class
• ne.class
• nf.class
• ng.class
• nl.class
• se.class
• In sample 00fb7a6e5f556c317561999fff52a3c2243b8b84
• Anallenge.class
• Base.class
• Kaniv.class
• Ntona.class
• Numcr.class
• Ocoo.class
• Ott.class
• Piic.class
• Samt.class
• Zaiia.class
• Zavv.class
• In sample 2f919db585ced2b348f5ce61539961531ce3942e
• Elocct.class
• lnKvxNcUi.class
• vkWZUyOU.class
• vqmmeibJ.class
• ymaUdhzsV.class
• In sample fbcba8a5ddc5de10ea6bb0120c5938723c4cae14
• MyApplet.class
• NioriutMdoritbause.class
• normutie.class
• QSortAlgorithm.class

Once the exploit gets full privileges on your PC, it may:

• 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 hard-coded in the exploit's file
• Take instructions from the HTML file (like a URL to the malware executable) that loaded them

Related information/references

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

• YAJ0: Yet Another Java Zero-Day - FireEye blog
• Oracle rushes out last-minute patch for vulnerabilities - ZDNet blog
• CVE-2013-1493 (jre17u15 - jre16u41) integrating Exploit Kits - Malware don't need Coffee

Analysis by Jeong Wook (Matt) Oh