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Win32/Waledac


Win32/Waledac is a trojan that is used to send spam. It also has the ability to download and execute arbitrary files, harvest email addresses from the local machine, perform denial of service attacks, proxy network traffic and sniff passwords.


What to do now

Manual removal is not recommended for this threat. To detect and remove this threat and other malicious software that may have been installed, run a full-system scan with an up-to-date antivirus product such as Microsoft Security Essentials, or the Microsoft Safety Scanner. For more information about using antivirus software, see http://www.microsoft.com/security/antivirus/av.aspx.

Threat behavior

Win32/Waledac is a trojan that is used to send spam. It also has the ability to download and execute arbitrary files, harvest email addresses from the local machine, perform denial of service attacks, proxy network traffic and sniff passwords.
Installation
In the wild, links to malicious Web sites hosting the trojan have been distributed via spam e-mail messages. Messages may contain content of current events such as holidays, historical, social and political events. If a user visits the link to the site hosting Win32/Waledac, the user could accidentally or unknowingly execute the trojan. This trojan does not copy itself to specific folders but does modify the registry to execute the trojan at each Windows start.
 
Adds value: "PromoReg"
With data: "<Win32/Waledac filename>"
To subkey: HKLM\Software\Microsoft\Windows\CurrentVersion\Run
 
If the trojan is unable to add the value and data to the 'HKLM' registry hive, 'HKCU' is used instead, as in this example:
 
Adds value: "PromoReg"
With data: "<Win32/Waledac filename>"
To subkey: HKCU\Software\Microsoft\Windows\CurrentVersion\Run
 
Win32/Waledac makes additional registry modifications.
 
Adds value: "MyID"
With data: <random hexadecimal string>
To subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion
 
Adds value: "RList"
With data:
<random hexadecimal string>
To subkey: HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion
Payload
Gathers e-mail addresses
When run, Win32/Waledac collects e-mail addresses found inside files stored on the infected computer. It searches fixed and remote drives for files to target, ignoring files with the following file extensions:
 
archive files
.7z
.gz
.zip
.rar
.jar
.hxw
.hxh
.hxn
.hxd
 
media files
.avi
.mov
.wmv
.mp3
.wave
.wav
.wma
.ogg
.vob
.png
.jpg
.jpeg
.gif
.bmp
 
executable files
.exe
.dll
.ocx
.class
.msi
 
Modifies security settings
Depending on how the affected computer is networked, Waledac may add itself to the Windows Firewall Authorized Applications list and in order to bypass the firewall when accessing the Internet. It adds the following 3 exceptions to the list for the name "Promo":
  • Communications via TCP port 80
  • Communications via UDP port 53
  • Communications from the Waledac executable itself
 
Steals sensitive data
Waledac attempts to steal sensitive data during transit. This could include user names and passwords. It targets the following protocols when attempting to capture sensitive data:
  • SMTP - port 25
  • POP - port 110
  • HTTP - port 80
  • FTP - port 21
 
Distributes and receives remote commands via distributed P2P network
Waledac can distribute and receive commands from other computers infected with Waledac via its own peer-to-peer (P2P) network. Using this distributed method of unauthorized access and control of an affected machine, a remote attacker can perform the following actions:
  • Download and execute arbitrary files
  • Perform Denial of Service attacks against a specified target
  • Establish SOCKS 5 Proxy (can be used for several purposes including hiding the origin of malicious network activity).
  • Start an HTTP server - port 80
  • Start a DNS server - port 53
  • Send captured data to a remote location
  • Sends e-mail messages after receiving configuration and targeting data
 
Waledac is distributed with an initial list of peers to contact. It has been observed contacting the following IP addresses in this fashion:
 
114.121.11.161
114.121.94.207
114.139.151.178
114.240.77.108
114.243.227.170
114.30.78.72
114.48.26.148
114.48.35.20
114.58.94.25
115.42.67.168
115.60.44.193
116.24.168.139
116.5.128.86
116.71.173.72
116.72.4.161
116.72.52.141
116.73.3.47
116.74.113.5
116.74.144.201
116.74.180.211
116.75.183.9
117.102.44.30
117.123.183.229
117.195.100.160
117.197.96.74
117.198.1.67
117.199.115.159
117.20.186.215
117.200.51.55
117.24.158.214
117.83.246.124
117.92.80.209
118.118.67.18
118.127.217.220
118.128.114.126
118.129.59.133
118.131.88.121
118.38.17.7
118.47.182.35
118.95.99.129
119.122.26.22
119.154.20.130
119.199.154.42
119.205.8.140
119.73.119.88
119.99.22.50
12.150.205.250
120.136.97.101
120.50.87.39
121.127.80.231
121.127.80.251
121.134.122.81
121.138.127.132
121.139.167.150
121.149.122.79
121.166.7.96
121.175.111.187
121.189.139.242
121.227.106.205
121.246.217.107
121.253.33.166
121.254.47.208
121.29.99.107
121.61.33.138
124.122.154.164
124.123.96.207
124.128.167.211
124.135.80.106
124.153.156.121
124.153.206.90
124.153.234.73
124.199.7.179
124.225.46.155
124.244.14.154
124.72.40.178
124.80.227.126
125.142.96.142
125.162.68.217
125.182.24.85
125.209.17.183
125.69.26.169
125.99.155.243
140.112.164.50
140.129.29.53
165.132.24.87
165.194.59.92
200.163.155.244
200.241.188.251
201.160.73.112
201.214.15.243
201.5.172.207
210.0.47.10
210.0.47.208
210.108.199.211
210.124.121.129
210.181.231.216
210.197.58.172
210.2.39.76
210.210.245.92
210.4.125.182
210.6.108.130
210.93.101.23
211.111.42.214
211.162.211.45
211.246.236.63
211.247.51.24
211.53.55.65
211.55.159.63
213.93.5.156
217.120.224.190
217.144.209.71
217.162.74.225
217.8.92.78
220.164.197.91
220.197.33.74
220.226.36.237
220.226.40.223
221.124.70.181
221.133.150.165
221.137.83.234
221.165.95.226
24.118.126.63
24.122.25.65
24.13.237.40
24.13.27.63
24.79.177.228
24.87.10.186
59.126.29.61
60.180.113.234
60.223.169.190
61.0.139.54
61.102.212.18
61.140.147.19
61.187.142.35
61.21.22.112
61.221.97.205
61.238.138.42
61.244.107.17
61.247.143.13
61.247.69.217
61.35.248.86
61.47.206.90
61.47.247.17
61.5.16.245
61.97.134.116
64.38.80.181
64.53.137.43
65.28.6.131
66.169.35.82
66.178.64.133
66.66.84.183
67.191.81.183
67.213.97.27
68.146.148.152
69.229.5.95
70.121.201.5
70.234.247.240
71.72.145.205
72.18.123.209
76.122.130.170
76.170.240.153
76.186.203.78
77.81.80.145
80.191.155.88
82.231.195.46
83.226.56.24
83.253.33.29
83.86.119.114
84.16.228.132
85.170.190.210
85.196.70.44
85.9.88.222
86.126.99.213
86.3.128.70
87.246.26.145
88.134.163.181
88.183.217.78
88.216.29.47
89.165.81.152
89.204.23.72
89.228.206.128
89.234.220.89
89.76.120.87
93.123.6.132
93.81.129.119
99.237.49.68
 
Analysis by Jireh Sanico and Scott Molenkamp

Symptoms

System Changes
The following system changes may indicate the presence of this malware:
  • The presence of the following registry subkeys:
    HKLM\Software\Microsoft\Windows\CurrentVersion\Run\PromoReg
    or HKCU\Software\Microsoft\Windows\CurrentVersion\Run\PromoReg
    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\MyID
    HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\RList

Prevention

Take the following steps to help prevent infection on your computer:
  • Enable a firewall on your computer.
  • Get the latest computer updates for all your installed software.
  • Use up-to-date antivirus software.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to Web pages.
  • Avoid downloading pirated software.
  • Protect yourself against social engineering attacks.
  • Use strong passwords.
Enable a firewall on your computer
Use a third-party firewall product or turn on the Microsoft Windows Internet Connection Firewall.
Get the latest computer updates
Updates help protect your computer from viruses, worms, and other threats as they are discovered. It is important to install updates for all the software that is installed in your computer. These are usually available from vendor Web sites.
 
You can use the Automatic Updates feature in Windows to automatically download future Microsoft security updates while your computer is on and connected to the Internet.
Use up-to-date antivirus software
Most antivirus software can detect and prevent infection by known malicious software. To help protect you from infection, you should always run antivirus software, such as Microsoft Security Essentials, that is updated with the latest signature files. For more information, see http://www.microsoft.com/protect/computer/viruses/vista.mspx.
Use caution when opening attachments and accepting file transfers
Exercise caution with e-mail and attachments received from unknown sources, or received unexpectedly from known sources.  Use extreme caution when accepting file transfers from known or unknown sources.
Use caution when clicking on links to Web pages
Exercise caution with links to Web pages that you receive from unknown sources, especially if the links are to a Web page that you are not familiar with, unsure of the destination of, or suspicious of. Malicious software may be installed in your computer simply by visiting a Web page with harmful content.
Avoid downloading pirated software
Threats may also be bundled with software and files that are available for download on various torrent sites. Downloading "cracked" or "pirated" software from these sites carries not only the risk of being infected with malware, but is also illegal. For more information, see 'The risks of obtaining and using pirated software'.
Protect yourself from social engineering attacks
While attackers may attempt to exploit vulnerabilities in hardware or software in order to compromise a computer, they also attempt to exploit vulnerabilities in human behavior in order to do the same. When an attacker attempts to take advantage of human behavior in order to persuade the affected user to perform an action of the attacker's choice, it is known as 'social engineering'. Essentially, social engineering is an attack against the human interface of the targeted computer. For more information, see 'What is social engineering?'.
Use strong passwords
Attackers may try to gain access to your Windows account by guessing your password. It is therefore important that you use a strong password – one that cannot be easily guessed by an attacker. A strong password is one that has at least 8 characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx.

Alert level: Severe
This entry was first published on: Apr 14, 2009
This entry was updated on: Apr 17, 2011

This threat is also detected as:
  • W32/Waledac.gen (McAfee)
  • W32.Waledac (Symantec)