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Discovered: December 23, 2008
Updated: August 08, 2012 10:11:56 AM
Also Known As: TROJ_GENETIK.TI [Trend], Email-Worm:W32/Waledac.A [F-Secure], Troj/Waled-C [Sophos], WORM_WALEDAC.C [Trend], WORM_WALEDAC.AB [Trend], WORM_WALEDAC.AS [Trend], Iksmas.A.worm [Panda Software], WORM_WALEDAC.AI [Trend], W32/Waled-Q [Sophos], W32/Waled-R [Sophos], Trojan:W32/Waledac.A [F-Secure], Troj/Waled-U [Sophos], W32/Waled-Z [Sophos], Troj/Waled-AB [Sophos], W32/Waled-AF [Sophos], Win32/Waledac.AJ [Computer Associates], Mal/WaledPak-B [Sophos], WORM_WALEDAC.BK [Trend], W32/Waled-AW [Sophos], Win32/Waledac.Z [Computer Associates], Mal/WaledPak-D [Sophos], WORM_WALEDAC.CRV [Trend], WORM_WALEDAC.ED [Trend], W32/Waledac.AX [Panda Software], WORM_WALEDAC.DU [Trend]
Type: Worm
Infection Length: 386,560 bytes
Systems Affected: Windows

W32.Waledac is a worm that spreads by sending emails that contain links to copies of itself. It also sends spam, downloads other threats, and operates as part of a botnet.

W32.Waledac doesn’t spread automatically, sending itself off to other computers in the traditional sense of most worms. Instead, the people behind this threat launch periodic campaigns in order to spread the worm. These generally come in the form of a spam campaign or fake websites and entail some sort of social engineering trick to entice users to perform various actions that result in the threat being installed.

In other situations W32.Waledac comes bundled with, or is downloaded by, other threats. The specific relationship between Waledac and these other threats isn’t always clear, but likely has much to do with the versatility of the threat.

W32.Waledac’s primary purpose is to make money. It does this by sending out spam and also by downloading and installing misleading applications. The spam that Waledac sends out appears to be for products tied to less-than-reputable vendors. The misleading applications that may be installed by the threat attempt to trick the user into paying for the applications. In both cases, the people behind Waledac likely make their money by receiving a portion of any profits made through misleading applications or by leasing out bandwidth, for a fee, to send spam.

Waledac also maintains a fairly robust botnet, with protection mechanisms and a decentralized architecture meant to make it difficult to bring down.

Symantec has observed the following geographic distribution of this threat.

Symantec has observed the following infection levels of this threat worldwide.

Antivirus signatures

Antivirus (heuristic/generic)

Intrusion Prevention System

Antivirus Protection Dates

  • Initial Rapid Release version December 23, 2008 revision 002
  • Latest Rapid Release version November 04, 2019 revision 019
  • Initial Daily Certified version December 23, 2008 revision 007
  • Latest Daily Certified version November 04, 2019 revision 065
  • Initial Weekly Certified release date December 24, 2008

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Technical Description

1. Prevention and avoidance
1.1 User behavior and precautions
1.2 Patch operating system and software
2. Infection method
2.1 Email
2.2 Fake websites
2.3 Bundled with other threats
3. Functionality
System modifications
3.2 Network activity
3.3 Spam
3.4 Downloading further risks
3.5 Infostealer
3.6 Botnet topology
4. Additional information

The following actions can be taken to avoid or minimize the risk from this threat.

1.1 User behavior and precautions
W32.Waledac relies heavily on social engineering in order to infect computers. The spam email campaigns used by attackers attempt to trick the user by referencing the latest news stories, seasonal holidays, or any number of other ruses.

Users should use caution when clicking links in such emails. Basic checks such as hovering with the mouse pointer over each link will normally show where the link leads to. Users can also check online website rating services such as safeweb.norton.com to see if the site is deemed safe to visit.

1.2 Patch operating system and software
The attackers behind this threat have been known to utilize exploit packs in order to craft Web pages to exploit vulnerable computers and infect them with W32.Waledac. Users are advised to ensure that their operating systems and any installed software are fully patched, and that antivirus and firewall software is up to date and operational. Users are recommended to turn on automatic updates if available so that their computers can receive the latest patches and updates when they are made available.

This threat is known to infect computers through a number of methods. We will examine each of these methods in more detail.

2.1 Email
The people behind Waledac periodically utilize spam campaigns with subject lines and message bodies based on the latest search terms or topical news stories. Topics have ranged from Christmas wishes , the 2009 US Presidential race , Valentine’s Day , the 4th of July , and even spying on your partner . These emails usually contain a link, often pointing to a Waledac binary hosted on a malicious website. In other cases they are brought to a fake website that continues the ruse and exploits vulnerable computers, installing its malicious software on the computer.

2.2 Fake websites
The fake websites designed by the people behind Waledac work in a variety of ways. They may simply attempt driveby download-style attacks, focusing on exploits for known (or sometimes 0-day) vulnerabilities. In other cases, the Waledac authors create fairly elaborate websites, attempting to add an air of legitimacy in order to trick the user into installing the threat, such as the following example:

2.3 Bundled with other threats
Waledac doesn’t just spread itself. It has made appearances with a surprising number of other threats. We have seen threats such as Trojan.Peacomm , W32.Downadup , and Trojan.Bredolab , among others, working in tandem with Waledac. The connection between these threats and Waledac is unknown, but is most likely a testament to its functionality once a computer has been compromised.


3.1 System modifications
The install files for Waledac vary widely, where each spam campaign or hosting website changes the file names, depending on the situation. There are even cases where Waledac utilizes server-side polymorphism, where the executables hosted on the malicious domains are repacked and encrypted at fairly regular intervals. This is no doubt an attempt to evade file-based detections when the threat initially arrives on a computer.

One consistent item in the installation of Waledac is the name of the registry entries that it creates. While the executable file names will vary, a registry entry called “PromoReg” should appear in the following locations:

  • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\"PromoReg" = "[PATH TO THREAT]"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run\"PromoReg" = "[PATH TO THREAT]"

It will also add its own configuration entries to the registry, hiding them in the “CurrentVersion” subkey. While the values will vary, the entries are as follows:

  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\"FWDone"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\"LastCommandId"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\"MyID"
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\"RList"

3.2 Network activity
Waledac utilizes network connections to carry out its primary functions: to spread spam, download other threats, and upload stolen information from the compromised computer. These features are discussed in detail in subsequent sections.

Besides this, Waledac has the ability to download updates of itself, as well as new components that provide further functionality for the threat. One of these “updates” is WinPcap, which is a legitimate application for monitoring network traffic. However, the threat uses it or less-than-benevolent purposes, assisting in its information stealing capabilities.

Waledac attempts to mask much of its downloading activities by hiding binary files within specially crafted .jpg files. These files contain fully executable code within them, which Waledac can then read and execute. However, these files still keep the JPEG functionality intact. If the user opens the file, the .jpg image will display as though there were nothing unusual about the file.

3.3 Spam
The people behind Waledac family of worms seem to be financially motivated. Given this, sending email spam ranks highly on its list of features. The threat sends out vast amounts of email for questionable products and services. These advertisements range from dubious job offers, to pharmaceuticals, to advertisements for online casinos.

In order to help facilitate the spamming feature, Waledac searches predetermined file types after its initial installation. It gathers any email addresses it finds on the compromised computer, adding them to its collection of addresses to send spam to.

3.4 Downloading further risks
We have also observed Waledac downloading other threats on to compromised computers. Some of the particular misleading applications use names such as Spyware Protect 2009 , System Security 2009, and MS AntiSpyware 2009.

Given the financial motives of the Waledac authors, it is likely that they receive a cut of any money garnered from the installation of any misleading applications “purchased” after Waledac installs them.

3.5 Infostealer
Waledac will also monitor standard Internet traffic, such as FTP, POP3, SMTP, and HTTP communications, searching for sensitive information such as user names, passwords, IP addresses, and any server information. While it collects this information and sends it to Waledac-controlled servers, it is unclear specifically what is being done with the data from there, though it is likely used to find and control further computers.

3.6 Botnet topology
The botnet that Waledac-infected computers join is comprised of three types of nodes.

  • Slave nodes: Perform the various functions of the threat, such as sending spam, installing other threats, and stealing information.
  • Relay nodes: Compromised computers with fast internet connections are often used to proxy traffic between slave nodes and the command and control (C&C) servers. The purpose of these nodes is to route the traffic through multiple points, making it more difficult to locate and shut down the C&C servers and the slave nodes.
  • C&C servers: These nodes send the commands through the relay nodes and on to the slave nodes, where the commands are performed.

Waledac uses a wide array of advanced features to keep it running and carrying out its primary functions. These include a wide array of custom communication protocols, fast-flux DNS networking, and sharing node IP lists.

For a detailed analysis of these advanced features, please see our whitepaper on Waledac .

We have also written a series of blog entries on Waledac , covering other topics relating to the threat.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.


You may have arrived at this page either because you have been alerted by your Symantec product about this risk, or you are concerned that your computer has been affected by this risk.

Before proceeding further we recommend that you run a full system scan . If that does not resolve the problem you can try one of the options available below.

If you are a Norton product user, we recommend you try the following resources to remove this risk.

Removal Tool

If you have an infected Windows system file, you may need to replace them using from the Windows installation CD .

How to reduce the risk of infection
The following resources provide further information and best practices to help reduce the risk of infection.

If you are a Symantec business product user, we recommend you try the following resources to remove this risk.

Identifying and submitting suspect files
Submitting suspicious files to Symantec allows us to ensure that our protection capabilities keep up with the ever-changing threat landscape. Submitted files are analyzed by Symantec Security Response and, where necessary, updated definitions are immediately distributed through LiveUpdate™ to all Symantec end points. This ensures that other computers nearby are protected from attack. The following resources may help in identifying suspicious files for submission to Symantec.

Removal Tool

If you have an infected Windows system file, you may need to replace them using from the Windows installation CD .

How to reduce the risk of infection
The following resource provides further information and best practices to help reduce the risk of infection.
Protecting your business network

The following instructions pertain to all current Symantec antivirus products.

1. Performing a full system scan
How to run a full system scan using your Symantec product

2. Restoring settings in the registry
Many risks make modifications to the registry, which could impact the functionality or performance of the compromised computer. While many of these modifications can be restored through various Windows components, it may be necessary to edit the registry. See in the Technical Details of this writeup for information about which registry keys were created or modified. Delete registry subkeys and entries created by the risk and return all modified registry entries to their previous values.

Writeup By: Ben Nahorney