Jynx Rootkit/2.0

Jynx2 is an expansion of the original Jynx LD_Preload rootkit written in C with several modifications for multi-factor authentication, a more compatible shell drop, and additional hiding features.

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Features

• Hiding from netstat
• Hiding from ps/top and /proc
• File hiding
• SSL connect accept() hook
• Multi-factor authentication
• Improved anti-removal features

Protip: It is possible to make Jynx2 even more difficult to remove by hooking C's link() function, therefore we recommend that any LD_Preload rootkit be removed using a LiveCD.

Archive Contents

 [root@ares jynx2]# ls
 Makefile  README  config.h  jynx2.c  packer.sh  reality.c

In this rendition of jynx, two shared libraries are built by the installation process. One, jynx2.so functions as the actual rootkit, while the other, reality.so, functions as a method for the remote access user to be able to see their own files and processes.

Configuration Options in Config.h

Improper configuration of Jynx2 can result in severe system instability, including segmentation faults of nearly every process on the infected host.

MAGIC_GID and MAGIC_UID

• Similar to the original Jynx Rootkit, Jynx2 will automatically hide processes, files, and connections owned by the magic UID or GID.

Protip: Due to the fact that adding a user/group to the machine may set off a HIDS, we recommend that the MAGIC_UID and MAGIC_GID be set to a commonly unused service user's information (e.g. cupsd or lp) for maximum IDS Evasion, as no files will suddenly disappear and the least files in /etc/ will be modified.

LIBC_PATH

       First of all, you need to dig into config.h, and ensure that the settings meet your needs.

MAGIC_STRING should be changed to the name of the directory you want to hide from the system. This can be used as a prefix to your main directory as well as for files. MAGIC_GID will be the Group ID to hide as well. Make sure that you set MAGIC_DIR Group ID to MAGIC_GID for hiding purposes as well. This will help disguise the processes from the system, including commands like ps. CONFIG_FILE defaults to ld.so.preload, which is usually located in /etc. You shouldn't have to change this unless you're going to dig a little deeper into hiding Jynx-Kit. MAGIC_ACK and MAGIC_SEQ have been dropped in Jynx2, since the new backdoor hooks accept() system call, and still includes SSL support. After installing Jynx2, ensure that you restart the daemon that you want to use as the backdoor.