English
The Internet threat alert status is currently normal. At present, no major epidemics or other serious incidents have been recorded by Kaspersky Lab’s monitoring service. Internet threat level: 1

Trojan-Downloader.Java.Agent.mq

Detected Jun 09 2011 10:55 GMT
Released Jun 09 2011 23:54 GMT
Published Sep 26 2011 11:49 GMT

Technical Details
Payload
Removal instructions

Technical Details

A trojan program that downloads files from the Internet without the user's knowledge and launches them. It is a Java-class (class-file). 6422 bytes.


Payload

The trojan is implemented as a class named "GoogleSearch", and is a Java-applet. It is launched from an infected HTML-page using the "<APPLET>" tag, for which a string containing encrypted links to the downloadable files is transferred in the "aaa" parameter. The links in this string are separated by the symbols "::". After launching, the trojan deciphers the links received using the "replaceAll" function. When decoding, the following mapping is used for input and output symbols:

Input symbols:

/UyuMaYRsL:WSKPv32tmcqdVEHik4bBr91=hGwOAF?#%-60Df5ZIzNxCT&pnQgo7XeJj.8_l
Output symbols:
0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/.:_-?&=%#
Later in the cycle, the files are downloaded from the unencrypted links. The executable file (.exe) or the dynamic-link library (.dll) may be downloaded from each link. The downloaded files are saved in the current user's temporary file directory as
%Temp%\<rnd>.exe
or
%Temp%\<rnd>.dll
where <rnd> is random fractional decimals between 0 and 1.

After a successful download, the executable file is launched. If downloading a dynamic-link library, this is launched using the "regsvr32.exe" system utility:

regsvr32 -s %Temp%\<rnd>.dll
During its implementation, the trojan uses the vulnerability CVE-2010-0840 in JRE (Java Runtime Environment). This vulnerability appears as a result of an incorrect validation when running preferred methods in JRE, which allows the attacker to execute an arbitrary code using an object that has been modified in a certain way, as a sub-class of the proxy class. This vulnerability allows the trojan to track and use methods which are not available for the Java-applet class which is a sub-class of the non-privileged "Applet" class.


Removal instructions

If your computer has not been protected with anti-virus software and has been infected with malware, you will need to take the following actions to delete this:

  1. Delete the original trojan file (its location on the infected computer will depend on how the program got onto the computer).
  2. Delete the following files:
    %Temp%\<rnd>.exe
    %Temp%\<rnd>.dll
    
  3. Update Sun Java JRE and JDK to the latest versions.
  4. Clear the Temporary Internet Files directory which may contain infected files (How to delete infected files in the Temporary Internet Files folder?).
  5. Run a full Kaspersky Antivirus scan of the computer with updated antivirus databases (download trial version).

MD5: 1ADF969912F790375C1EF13AB5C730B0
SHA1: 8FB0922188D1CE0F02A54E895BDC377EE2AB3350


Bookmark and Share
Share
Trojan-Downloader

Programs classified as Trojan-Downloader download and install new versions of malicious programs, including Trojans and AdWare, on victim computers. Once downloaded from the Internet, the programs are launched or included on a list of programs which will run automatically when the operating system boots up.

Information about the names and locations of the programs which are downloaded are in the Trojan code, or are downloaded by the Trojan from an Internet resource (usually a web page).

This type of malicious program is frequently used in the initial infection of visitors to websites which contain exploits.


Other versions