Joe Security's Blog

Recently we came across an interesting sample which seems to be related to Elise Malware. Elise is tight to the Dragon Fish and Lotus Blossom APT groups which primary targets governments and defense contractors. Elise is known to infect victims by using the latest exploits available and is often packed with interesting Sandbox evasion techniques.

In this blog post, we will dissect the latest version of Elise.

The sample under investigation is distributed as an Office document lure. To be more precise in Rich Text Format.

CVE-2018-0802

We start the analysis by having a look at the behavior graph and acknowledge that the process EQNEDT32.EXE was started among Winword.exe:



This process is the Microsoft Office Equation Editor. In November 2017 the security company Embedi detected an exploit in EQNEDT32.EXE which later got the identification CVE-2017-11882. Microsoft patched the flaw in November.

So, is Elise using this exploit? To answer this question we had a detailed look at the exploit itself. The outcome: no it is not CVE-2017-11882 but rather CVE-2018-0802. CVE-2018-0802? This a second exploit also included in EQNEDT32.EXE which was detected in later December.

We extracted the trampoline and shellcode:



The code renames and loads the PE file (named a.b) previously dropped by Word. The newly loaded code is then injected into IExplorer.exe where the main payload is executed:

Sandbox Evasions

VMware backdoor check

Disk Name Check

Check for various Analysis Tools

Process Check

Mac Address Check

Payloads

Add a Proxy to Internet Explorer

Add a Proxy to Firefox