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Win32/Qakbot


Win32/Qakbot is a multi-component family of malware that allows unauthorized access and control of an affected computer. By allowing remote access, this backdoor trojan can perform several actions including stealing sensitive information. Some variants of this malware may attempt to spread to open shares across a network, including the default shares C$ and Admin$.


What to do now

To detect and remove this threat and other malicious software that may be installed in your computer, run a full-system scan with an up-to-date antivirus product such as the following:
 
 
For more information on antivirus software, see http://www.microsoft.com/windows/antivirus-partners/.
 
Recovering from recurring infections on a network
The following additional steps may need to be taken to completely remove this threat from an infected network, and to stop infections from recurring from this and other similar types of network-spreading malware:
 
  1. Ensure that an antivirus product is installed on ALL computers connected to the network that can access or host shares.
  2. Ensure that all available network shares are scanned with an up-to-date antivirus product.
  3. Restrict permissions as appropriate for network shares on your network. For more information on simple access control, please see: http://technet.microsoft.com/library/bb456977.aspx.
  4. Remove any unnecessary network shares or mapped drives.
 
Note: Additionally it may be necessary to temporarily change the permission on network shares to read-only until the disinfection process is complete.

Threat behavior

Win32/Qakbot is a multi-component family of malware that allows unauthorized access and control of an affected computer. By allowing remote access, this backdoor trojan can perform several actions including stealing sensitive information. Some variants of this malware may attempt to spread to open shares across a network, including the default shares C$ and Admin$.
Installation
Win32/Qakbot can infect a computer through a number of exploit-based attacks or by being downloaded and installed by other malware. In the wild, we have observed Qin32/Qakbot being hosted on a number of malicious web sites that attempt to exploit vulnerabilities in Adobe flash.
 
We have observed the following hosts being used to install Win32/Qakbot:
  • nt11.co.in
  • nt002.cn
  • nt16.in
 
Using these hosts, Qakbot downloads an installer which then downloads more components. The installer downloads an archive package, which is decrypted and installed by the installer.\
 
Older variants of Qakbot used the following file names for their components:
msadvapi32.dll
_qbot.cb
_qbotinj.exe
_qbot.dll
_qbotnti.exe
seclog.txt
si.txt
ps_dump
qa.bin
 
More recent variants alias these files to randomly generated file names, for example:
msadvapi32.dll=voxivm94cw.dll
_qbot.cb=voxivm9.dll
_qbotinj.exe=voxivm94.exe
_qbot.dll=voxivm94.dll
_qbotnti.exe=voxivm94lx.exe
seclog.txt=voxivm.dll
si.txt=ibggih
ps_dump=yamy
qa.bin=axnrkeg
nbs=ziqotf
 
These randomly generated file names differ on each machine on which the malware is installed. The file names are built around a randomized root, with additional randomized characters based on information stolen from the affected computer.
 
Once installed, Qakbot replaces existing registry data found in subkey "HKLM\Microsoft\Windows\CurrentVersion\Run" in order to execute the malware at each Windows start. The malware prepends itself to a previously existing entry.
Spreads via…
Network shares
Win32/Qakbot may attempt to spread to open shares across a network, including the default shares C$ and Admin$.
Payload
Allows backdoor access and control
Win32/Qakbot may connect to a remote server in order to receive commands from a remote attacker. Commands could include any of the following actions:
  • Log keystrokes
  • Get the host's IP address and name
  • Steal cookies and certificates
  • Monitor Favorites and visited URLs
  • Steal passwords from Internet Explorer, MSN Messenger, and Outlook
  • Steal Autocomplete information
  • Download and install updates
  • Upload stolen data to an FTP server
 
Performs stealth
Recent variants of Win32/Qakbot employ a rootkit that hooks various APIs and hides the Qakbot installation directory and files, as well as the registry entry that loads the malware.
 
Additional information

The MMPC has written a threat report on the Qakbot family. You can download the report from this page.

Analysis by Dan Kurc

Symptoms

Alert notifications or detections of this malware from installed antivirus or security software may be the only other symptoms.

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.
  • Limit user privileges on the computer.
  • Use caution when opening attachments and accepting file transfers.
  • Use caution when clicking on links to webpages.
  • 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 websites.
 
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/windows/antivirus-partners/.
Limit user privileges on the computer
Starting with Windows Vista and Windows 7, Microsoft introduced User Account Control (UAC), which, when enabled, allowed users to run with least user privileges. This scenario limits the possibility of attacks by malware and other threats that require administrative privileges to run.
 
You can configure UAC in your computer to meet your preferences:
Use caution when opening attachments and accepting file transfers
Exercise caution with email 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 webpages
Exercise caution with links to webpages that you receive from unknown sources, especially if the links are to a webpage 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 webpage 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 to compromise a computer, they also attempt to exploit vulnerabilities in human behavior to do the same. When an attacker attempts to take advantage of human behavior 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 eight characters, and combines letters, numbers, and symbols. For more information, see http://www.microsoft.com/protect/yourself/password/create.mspx.

Alert level: Low
This entry was first published on: Dec 09, 2010
This entry was updated on: Jun 09, 2011

This threat is also detected as:
  • Trojan.Win32.Bzud (Kaspersky)
  • Trojan-PSW.Win32.Qbot (Kaspersky)
  • W32/Pinkslipbot (McAfee)
  • Bck/QBot (Panda)
  • Mal/Qbot (Sophos)
  • W32.Qakbot (Symantec)
  • TSPY_QAKBOT (Trend Micro)
  • Backdoor.Qakbot (VirusBuster)