Backdoor.Bofishy.C

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Discovered: November 14, 2002
Updated: February 13, 2007 11:52:28 AM
Also Known As: tcpdump trojan
Type: Trojan Horse
Systems Affected: Linux, UNIX


Backdoor.Bofishy.C is a Trojan that affects the libpcap packet capture library and the tcpdump sniffer. It comes as modified source packages that create a backdoor process during their installation. The backdoor process attempts to contact the attacker's computer and give the attacker access to a shell on the local computer.

Antivirus Protection Dates

  • Initial Rapid Release version November 14, 2002
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version November 14, 2002
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date November 20, 2002

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

Writeup By: Frederic Perriot

Discovered: November 14, 2002
Updated: February 13, 2007 11:52:28 AM
Also Known As: tcpdump trojan
Type: Trojan Horse
Systems Affected: Linux, UNIX


Backdoor.Bofishy.C affects the "configure" scripts of libpcap-0.7.1, tcpdump-3.6.2, tcpdump-3.7.1, and possibly other versions of the libpcap and tcpdump source packages.

When an affected package is installed, the modified "configure" script downloads the "services" file from the mars.raketti.net Web site and executes it as a script. The "services" file poses as a normal list of services similar to the one located under /etc/services, but it contains embedded instructions that create a backdoor process on the computer.

The "services" script first drops a C program named conftes.c, compiles it under the name of the current user's shell, and then executes it. The conftes.c program connects to the IP address 212.146.0.34 on port 1963/tcp and accepts commands from an attacker. One command opens a shell for the attacker on the infected computer.

The script then deletes the backdoor binary, and then deletes itself.

Additionally, the libpcap source package contains a modified version of the pcap_compile() function in file gencode.c. This function is responsible for building a packet-filtering rule from a command-line argument. The modified function adds a rule to prevent packet capture on port 1963, the port that is used by the backdoor. As a result, it is impossible to use (the Trojan-infected) libpcap and tcpdump to detect the network traffic that is generated by the backdoor.

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.

Writeup By: Frederic Perriot

Discovered: November 14, 2002
Updated: February 13, 2007 11:52:28 AM
Also Known As: tcpdump trojan
Type: Trojan Horse
Systems Affected: Linux, UNIX


NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Update the virus definitions.
  2. Run a full system scan, and delete all files that are detected as Backdoor.Bofishy.C. Deleted files must be replaced and recompiled.

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
  • Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.

    Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

To scan for and delete the infected files:
  1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
  2. Run a full system scan.
  3. If any files are detected as infected with Backdoor.Bofishy.C, click Delete. Deleted files must be replaced and recompiled.


Writeup By: Frederic Perriot