Win32.Worm.Welchia.A
( W32.Welchia.Worm, W32/Nachi.worm, WORM_MSBLAST.D )| Spreading: | high | |
| Damage: | low | |
| Size: | 10240 (packed with upx and patched) | |
| Discovered: | 2003 Aug 18 |
SYMPTOMS:
Presence of dllhost.exe and svchost.exe files in %system32%\\wins directory (e.g. C:\\Windows\\System32\\Wins\\DllHost.exe).Presence of two services: Network Connections Sharing with the path to executable: %system32%\\wins\\svchost.exe and WINS Client with the path to executable: %system32%\\wins\\dllhost.exe.
TECHNICAL DESCRIPTION:
For Windows XP systems, it uses the Windows DCOM RPC vulnerability described in MS03-026 security bulletin, to infect new computers.For systems that have the IIS service, it uses the Windows WebDav vulnerability described in MS03-007 security bulletin, to infect new computers.
When ran it looks for Win32.Msblast.A worm file (msblast.exe) and tries to remove it from the computer. It also attempts to download the patch for the DCOM RPC vulnerability and to install it. If it successfully installs it, it restarts the computer without notice.
After infecting a remote computer, it opens a random TCP port between 666 and 765, on the remote computer so as to send commands to it.
It uses the TFTP file transfer protocol to copy the worm body: dllhost.exe, and the TFTP server: tftpd.exe, that will be renamed to svchost.exe after copying in %system32%\\wins.
It creates two services: Network Connections Sharing with the path to executable: %system32%\\wins\\svchost.exe and WINS Client with the path to executable: %system32%\\wins\\dllhost.exe, that are set to run automatically, so that the worm will be active, even if no user is logged on the computer.
The worm contains some text strings: I love my wife & baby :), Welcome Chian, Notice: 2004 will remove myself:) and sorry zhongli. It is true, from the year 2004 it would uninstall itself from the infected machine.
The mutex that it uses not to run twice on the same computer is named RpcPatch_Mutex.
Removal instructions:
The BitDefender Virus Analyse Team has releasead a free removal tool for this particular virus.
Important: You will have to close all applications before running the tool (including the antivirus shields) and to restart the computer afterwards. Additionally you\'ll have to manually delete the infected files located in archives and the infected messages from your mail client.
The BitDefender Antiwelchia-en.exe tool does the following:
You may also need to restore the affected files.
First apply the patches for the two vulnerabilities used by this worm:
- For DCOM RPC, download and install the patch released by Microsoft: MS03-026 (at the end of the page).
- For WebDav, download and install the patch released by Microsoft: MS03-007 (at the end of the page).
- Right-click on My Computer and select Manage from the menu. Maximize the Computer Management window that appears.
- In the left side of the window, click on Services and Applications. In the right side of the window, double-click on Services.
- In the list of services, click on the column title Name so as to sort the service names alphabetically. If you click twice, the service names will be sorted in reverse order.
- Find the service Network Connections Sharing. Right-click on it, and select Properties from the menu. Look in the Properties window and assure that the Path to executable is %system32%\\wins\\svchost.exe (e.g. C:\\Windows\\System32\\wins\\svchost.exe). Press the Stop button (if it is not disabled), to stop the service.
- Find the servce WINS Client, make sure the Path to executable is %system32%\\wins\\dllhost.exe and stop it too.
- Go to Start, Run and open regedit.exe. Go to to the registry key:
HKLM\\SYSTEM\\CurrentControlSet\\Services
and delete the values RpcTftpd and RpcPatch. - Restart your computer.
- Go to %system32%\\wins and delete the files svchost.exe and dllhost.exe.
ANALYZED BY:
Mircea Ciubotariu, Mihai Neagu, Bogdan Dragu.Bitdefender e-Guides Series
The Bitdefender e-Guides series is a learning initiative aiming to provide the Bitdefender reader and user community with valuable information about e-threats and the security issues of the IT&C realm, while also offering practical advice and feasible solutions to their on-line defense needs. The Bitdefender security analysts share their knowledge in malware prevention, identification and annihilation, with an emphasis on on-line privacy and different technologies, countermeasures and cybercrime prevention methods.
Covering topics that range from kids and family's on-line protection, safe social networking and preventing data safety breaches to securing enterprise environments, the e-Guides series is intended for a broad audience of small organizations and individual users concerned about the safety and integrity of their networks and systems. The e-Guides also address issues pertaining to the daily activity of IT&C Systems Security Managers, System and Network Administrators, Security Technology Developers, Analysts, and Researchers.
Safe Blogging Guide
Tips and tricks on how to keep your blog and your identity safe
Blogging is one of the most popular forms of written expression on the web, with more than 150 million indexed blogs worldwide. While regular readers are looking for pieces of information and articles, cyber-crooks take a different interest in them. Finding private information and getting cheap storage space for their malware campaigns are only two of the multitude of users they may subject your blog to.
This material covers the basic guidelines for safe blogging and is especially focused on individual blogs that are either self-hosted or provided as a service by major blog providers.
Securing Wireless Networks Guide
Tips and tricks on how to shield your home network from intruders
This document is intended for computer users who have deployed or plan to deploy a home wireless network. At a time when wireless communication has become a significant part of our lives, cyber-criminals try to exploit every security breach in the wireless configuration in order to intercept traffic or use the internet connection for illegal purposes.
The following guide will teach you the best practices when using unsecured wireless networks, as well as how to properly configure your home router or access point to prevent others from abusing your network.
Protecting Children On-line Guide
How to secure and defend the digital experience of your kids
This document is intended for family, parents and teachers and its purpose is to help secure the digital activities of kids and teens. In an age when the mass production and accessibility of computers have turned these devices into regular family or household commodities, children get familiar with PCs and Internet from a very fresh age. Despite its obvious communication-related benefits, the WWW can also be a hazardous place for kids, with e-threats directly targeting their age group and their home or school computers.
This e-Guide covers the main risks and dangers for kids on-line, such as cyber-bulling, exposure to inappropriate content, on-line addiction and other harmful online actions, while also focusing on topics such as malware, phishing, ID theft and spam, to which teenagers, just as any other Internet users, are exposed nowadays. A Safety Tips section helps parents and teachers better understand and deal with these issues in relation to the kids.
Silver Surfers On-line Safety Guide
How to protect valuable ideas and assets from cyber-hacking
This document is intended for families and senior citizens and its purpose is to help them browse the web safely and enjoy their on-line activities.
At a first glance, it would appear that senior citizens are exposed to cybercrime just as much as any other inexperienced Internet user, irrespective of their age. However, as this e-Guide shows through several case studies, there are several risks and dangers targeting directly silver surfers, such as pension delivery and fallacious tax paying methods or income-related scams. Examples, tips and advice complement the case studies and provide readers with useful guidelines in their daily on-line routine.
Preventing Data Breaches Guide
How to protect valuable ideas and assets from cyber-hacking
The e-guide was designed to cover the various potential sore points of business data safety, from the matter of the network's physical integrity to the complicated mechanisms of business targeted cybercrime (e.g. banker Trojans, phishing). This material is also intended to match, though not in as much detail as a full-fledged technical description, the features of the various consumer and business oriented Bitdefender solutions to the situations in which they might come in handy to IT administrators.
Consulting this document would be useful in the process of deciding what's best for small to medium-sized networks security and a solid basis for further comparative research on this subject.
White Papers
- Facebook Whitepaper
- Bitdefender Antivirus Technology
- B-HAVE ,The Road to Success
- The medium or the message? Dealing with image spam, December 2006,Virus Bulletin
- Fighting Image Spam
- Bitdefender NeuNet Antispam Technology
- Proactive security I body armor against business attacks
- Whitepaper-Emerging Threats to Business Security
- Securing the Uncertain Bitdefender's B-HAVE Proactive Technology for Defense against Versatile_Threats
- Securing E-Mail-The First Strategic Defense Line
- Virus Naming. The "Who's Who?" Dilemma
- Facebook – Another breach in the wall
- Bitdefender Active Virus Control: Proactive Protection Against New and Emerging Threats
Bitdefender E-Threats Landscape Reports
The purpose of this report is to provide a comprehensive investigation of the threats’ landscape. Bitdefender’s security experts thoroughly analyze and examine the menaces of the each semester, focusing on software vulnerabilities and exploits, different types of malware, as well as countermeasures, cyber crime prevention and law enforcement.The E-Threats Landscape Report concentrates mainly on the latest trends, but it also contains facts and data and concerning the previously investigated periods, as well as several predictions related to the upcoming semesters.This document is primarily intended for IT&C System’s Security Managers, System and Network Administrators, Security Technology Developers, Analysts, and Researchers, but it also addresses issues pertaining to a broader audience, like small organizations or individual users concerned about the safety and integrity of their networks and systems.
H2 2011 E-Threat Landscape Report - Overview
Twenty years ago, a revolutionary means of electronic communication was born. It would become so popular with all ages and professions that it is still the most used data communication mechanism even today: introducing the SMS – the short message service.
Today, mobile phones are more than bulky gadgets that can move voice and messages from one point to another: they are must-have gear in a World 2.0 – so powerful and so complex, running their own operating systems and, consequently, facing their share of cyber-trouble. While the first six months of 2011 were marked by software vulnerabilities and high-profile data breaches, the second half cast the spotlight on not only a new family of malware, but also uncovered a user espionage scandal that apparently involved an array of mobile phone carriers and the controversial software vendor CarrierIQ.
The malware landscape was dominated by Trojan.Autorun.Inf and Win32.Worm.Downadup, two malicious contenders that have roots in the Windows XP era, but managed to keep their places even though operating system upgrades or applying patches would have solved security issues exploited by these pieces of malware. The top contenders for H2 2011 are Trojan.AutorunInf, Win32.Worm.Downadup, and Exploit.CplLnk.
Data breaches attributed to the Anonymous gang and its satellite hacking groups continued throughout the second half of 2011. Among the most important targets were Mitsubishi Heavy Industries, Adidas, RIM, Tiroler Gebietskrankenkasse, Nexon and even the United Nations. Corporate trust also came under close scrutiny, as the DigiNotar incident in H1 2011 exposed unwary users to a massive phishing attack that used stolen digital certificates generated for high-profile institutions and government agencies such as Google, Tor, CIA and Israel’s Secret Service, the Mossad.
Social networks have also played a key role in disseminating malware and spreading fake news about the deaths of high-profile personalities such as Muammar Gaddafi or Steve Jobs. Of particular importance were the malicious campaigns built around the alleged movie of Gaddafi’s execution and the commemorative giveaway in honor of the late Steve Jobs.
Download now the full H2 2011 E-Threat Landscape Report (pdf)
Download now the executive summary H2 2011 E-Threat Landscape Report - Executive Summary (pdf)
Archive
2011
Download now H1 2011 E-Threats Landscape Report - Executive Summary (pdf)
2010
Download now H2 2010 E-Threats Landscape Report - Executive Summary (pdf)
Download now H2 2010 E-Threats Landscape Report (pdf)
Download now H1 2010 E-Threats Landscape Report - Executive Summary (pdf)
Download now H1 2010 E-Threats Landscape Report (pdf)
2009
Download now H1 2009 Malware and Spam Review Executive Summary (pdf)
Download now H1 2009 E-Threats Landscape Report (pdf)
Download now H2 2009 Malware and Spam Review (pdf)
Download now H2 2009 E-Threats Landscape Report - Executive Summary (pdf)
2008
Download now H1 2008 E-Threats Landscape Report (pdf)
Download now H2 2008 E-Threats Landscape Report (pdf)
Who to ask? Below you have a list of all of our media representatives who are ready to answer any question you might have.
Global PR Manager