Office (OOXML) malware analysis — malicious · a8b1fd483d74fb13

MALICIOUS

Office (OOXML)

41.8 KB Created: 2021-06-22 12:43:05 UTC Authoring application: Microsoft Excel 16.0300

MD5: 6adb68fe55365120bb1293fe0b4afa23 SHA-1: 6cad911730f6582148243909e01ed756d2c49eeb SHA-256: a8b1fd483d74fb1388922c6de1f223484d79b9f90e399bbd069533a683632343

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File T1087.002 Local Account T1059.003 Windows Command Shell

The file contains a Workbook_Open macro that triggers obfuscated VBA code. This code references cmd.exe and PowerShell, and critically uses WMI (Win32_Process) to launch a process. The VBA code appears to be a Base64 decoder, suggesting it decodes and executes a payload. The presence of these elements strongly indicates a macro-based downloader.

Heuristics 6

PowerShell reference in VBA critical OLE_VBA_PS

PowerShell reference in VBA
VBA WMI Win32_Process launcher critical OLE_VBA_WMI_PROCESS_CREATE

VBA macro builds or references a WMI moniker for Win32_Process and invokes .Create to start a command. This is a high-confidence macro execution chain that often hides the WMI class name through string concatenation or helper functions.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
GetObject call high OLE_VBA_GETOBJ

GetObject call
cmd.exe reference in VBA high OLE_VBA_CMD

cmd.exe reference in VBA
VBA project inside OOXML medium OOXML_VBA

Document contains a VBA project — VBA macros present

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `9263f18c294964fc31ea20c269952e28eead94a0c36c7e0c9ea444bfeffe47d8`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	35225 bytes
`vbaProject_00.bin` `f1514a405ae34941b384352671ee5050d59397a9cc01e3520ecedef778c31ece`	vba-project	OOXML VBA project: xl/vbaProject.bin	11264 bytes

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