Trojan.Peacomm.B

When the Trojan is executed, it checks for the presence of the following two applications and will shut down the compromised computer if either of those programs are present:
VMWare
VirtualPC

The Trojan then creates the following mutex so that only one copy of the threat is running on the compromised computer:
A8dK894Lm9#F2i$s0Bq2X

Next it drops the following files:

• %System%\windev-[RANDOM 4 DIGITS]-[RANDOM 4 DIGITS].sys
• %System%\windev-peers.ini

It registers the malicious .sys file as a new device service driver with the following characteristics:
Display Name: windev-[RANDOM 4 DIGITS]-[RANDOM 4 DIGITS]
Image Path: %System%\windev-[RANDOM 4 DIGITS]-[RANDOM 4 DIGITS].sys

The Trojan then creates the following registry subkey to install the above service:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\windev-[RANDOM 4 DIGITS]-[RANDOM 4 DIGITS]

The Trojan may then hook the following APIs to hide the presence of the device service and the associated file:

• NtQueryDirectoryFile
• NtEnumerateKey
• NtEnumerateValueKey

It also hooks the TCP/IP driver to hide the network port used for its malicious activity.

Once loaded, the device driver searches for the SERVICES.EXE process and injects a hidden module into it and run threads into this process.

The Trojan then drops an encrypted list of initial peers into one of the following configuration files:
%System%\windev-peers.ini

It opens and then listens on the following ports which are used for encrypted communication channels with other peers:

• UDP port 7871
• UDP port 8815

Next, the Trojan registers the compromised computer as a peer in the existing peer-to-peer network, using the Overnet protocol by connecting to the peers specified in the initial peer list.

The peer-to-peer network can then be used by a malicious user to retrieve information on what files to download and execute and to send commands to the compromised computer.

The hidden module injected into SERVICES.EXE performs the following actions:

• Gather confidential computer information, such as the OS version
• Disable the Windows Firewall by changing the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess
• Gather email addresses from the compromised computer by searching for files with the following extensions:
  
  • .adb
  • .asp
  • .cfg
  • .cgi
  • .dat
  • .dbx
  • .dhtm
  • .eml
  • .htm
  • .jsp
  • .lst
  • .mbx
  • .mdx
  • .mht
  • .mmf
  • .msg
  • .nch
  • .ods
  • .oft
  • .php
  • .pl
  • .sht
  • .shtm
  • .stm
  • .tbb
  • .txt
  • .uin
  • .wab
  • .wsh
  • .xls
  • .xml

• Send spam e-mails using its own SMTP engine
• Avoids sending e-mails to the following recipients:
  
  • @avp.
  • @foo
  • @iana
  • @messagelab
  • @microsoft
  • abuse
  • admin
  • anyone@
  • bsd
  • bugs@
  • cafee
  • certific
  • contract@
  • f-secur
  • feste
  • free-av
  • gold-certs@
  • google
  • help@
  • icrosoft
  • info@
  • kasp
  • linux
  • listserv
  • local
  • news
  • nobody@
  • noone@
  • noreply
  • ntivi
  • panda
  • pgp
  • postmaster@
  • rating@
  • root@
  • samples
  • sopho
  • spam
  • support
  • unix
  • update
  • winrar
  • winzip

• Write the value data of the following registry entry into %System%\windev-peers.ini:
  HKEY_LOCAL_MACHINE\Microsoft\Windows\ITStorage\Finders\"config" = "[P2P NETWORK UNIQUE ID]"
• Download and execute remote files through HTTP protocols.
  

Once the firewall has been disabled, the Trojan reportedly attempts to download files from the following host:
[http://]66.228.117.195

Recommendations

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.

Summary