Beyond good ol’ Run key, Part 133

March 5, 2021 in Anti-Forensics, Autostart (Persistence)

Java programs compiled into executable form using launch4j have a few interesting features that make them a good target for both persistence and LOLBIN-ish activities.

When the executable starts it checks the environment for a presence of Java Runtime Environment (JRE) and while doing so it is checking a number of locations:

  • 64-bit search: HKLM\SOFTWARE\JavaSoft\Java Runtime Environment
  • 32-bit search: HKLM\SOFTWARE\JavaSoft\Java Runtime Environment
  • 64-bit search: HKLM\SOFTWARE\JavaSoft\Java Development Kit
  • 32-bit search: HKLM\SOFTWARE\JavaSoft\Java Development Kit
  • 64-bit search: HKLM\SOFTWARE\JavaSoft\JRE
  • 32-bit search: HKLM\SOFTWARE\JavaSoft\JRE
  • 64-bit search: HKLM\SOFTWARE\JavaSoft\JDK
  • 32-bit search: HKLM\SOFTWARE\JavaSoft\JDK
  • 64-bit search: HKLM\SOFTWARE\IBM\Java Runtime Environment
  • 32-bit search: HKLM\SOFTWARE\IBM\Java Runtime Environment
  • 64-bit search: HKLM\SOFTWARE\IBM\Java2 Runtime Environment
  • 32-bit search: HKLM\SOFTWARE\IBM\Java2 Runtime Environment
  • 64-bit search: HKLM\SOFTWARE\IBM\Java Development Kit
  • 32-bit search: HKLM\SOFTWARE\IBM\Java Development Kit

The JAVA_HOME environment variable is not being used.

Placing malicious entry under any of these branches e.g.:

[HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Development Kit\1.8]
"JavaHome"="c:\test"

and then dropping malicious c:\test\jre\bin\javaw.exe will cause the original program compiled with launch4j 9when launched) to spawn that malicious javaw.exe.

And as a little bonus, the stub of launch4j accepts these debug command line arguments (or uses equivalent values of environment variables shown in parenthesis):

  • –l4j-debug (or Launch4j=*debug*)
  • –l4j-debug-all (or Launch4j=*debug-all*)

When any of these two are present a launch4j.log log file will be created with all the information needed for troubleshooting (the second option generating more verbose version of the log file).

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