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Linux.Darlloz

Risk Level 2: Low

Discovered:
November 26, 2013
Updated:
December 12, 2013 2:14:03 PM
Type:
Worm
Infection Length:
Varies
Systems Affected:
Linux
CVE References:
CVE-2012-1823, CVE-2012-2311, CVE-2012-2335, CVE-2012-2336
The worm propagates by exploiting the PHP 'php-cgi' Information Disclosure Vulnerability (CVE-2012-1823) through http POST requests.

If the target is vulnerable, it downloads and executes the worm from the following URL:
[http://]www.gpharma.co

When the worm is executed, it copies itself as the following file:
/tmp/x86

The worm creates the following directory:
/var/run/.zollard/

The worm attempts to force load ip_table or iptable from the following locations:
  • /lib/modules/[OS VERSION]/kernel/net/ipv4/netfilter/ip_tables.ko
  • /lib/modules/[OS VERSION]/kernel/net/ipv4/netfilter/iptable_filter.ko

The worm configures iptable to drop packets on TCP port 23 and prevents remote users from connecting to the compromised computer.

The worm attempts to terminate the following process:
telnetd

The worm attempts to terminate the process ID written in the following processes and to delete the files:
  • /var/run/.lightpid
  • /var/run/.aidrapid
  • /var/run/lightpid

The worm deletes the following files:
  • /var/run/.lightscan
  • /var/run/lightscan
  • /var/run/mipsel
  • /var/run/mips
  • /var/run/sh
  • /var/run/arm
  • /var/run/ppc
  • /var/run/m
  • /var/run/mi
  • /var/run/s
  • /var/run/a
  • /var/run/p
  • /var/run/msx
  • /var/run/mx
  • /var/run/sx
  • /var/run/ax
  • /var/run/px
  • /var/run/32
  • /var/run/sel
  • /var/run/pid
  • /var/run/gcc
  • /var/run/dev
  • /var/run/psx
  • /var/run/mpl
  • /var/run/mps
  • /var/run/sph
  • /var/run/arml
  • /var/run/mips.l
  • /var/run/mipsell
  • /var/run/ppcl
  • /var/run/shl
  • /bin/pp
  • /bin/mi
  • /bin/mii
  • /var/tmp/dreams.install.sh
  • /var/tmp/ep2.ppc
  • /usr/bin/wget
  • /usr/bin/-wget

The worm generates random IP addresses excluding the following:
  • 0.0.0.0 - 0.255.255.255
  • 127.0.0.1 - 127.255.255.255
  • 192.0.2.0 - 192.0.2.255
  • 198.51.100.0 - 198.51.100.255
  • 203.0.113.0 - 203.0.113.255
  • 255.255.255.255

If the worm cannot access TCP port 23, it attempts to send malformed http POST requests to the following paths:
  • /cgi-bin/php
  • /cgi-bin/php5
  • /cgi-bin/php-cgi
  • /cgi-bin/php.cgi
  • /cgi-bin/php4

If the worm successfully accesses TCP port 23, it creates the following directory:
/var/run/.zollard/

The worm copies the following files to the directory on the remote computer:
  • /var/run/.zollard/arm
  • /var/run/.zollard/ppc
  • /var/run/.zollard/mips
  • /var/run/.zollard/mipsel
  • /var/run/.zollard/x86
  • /var/run/.zollard/nodes
  • /var/run/.zollard/sig

The worm executes one of the following files:
  • /var/run/.zollard/arm
  • /var/run/.zollard/ppc
  • /var/run/.zollard/mips
  • /var/run/.zollard/mipsel
  • /var/run/.zollard/x86

The worm opens a back door on TCP port 58455 and waits for commands.

      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: Kaoru Hayashi
      Summary| Technical Details| Removal

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