Office (OOXML) / .XLSM malware analysis — malicious · 0186ed5e1eeb88d9

MALICIOUS

Office (OOXML) / .XLSM

159.3 KB Created: 2021-03-24 13:12:27 UTC Authoring application: Microsoft Excel 15.0300

MD5: 5a1bb3891c09bb59e95f0ff47e8ec3db SHA-1: 2e1fc20428890f9fca07f995f6095527d90d497e SHA-256: 0186ed5e1eeb88d98e6d8686e0ed26ed76f8dec80ef3fd1bf3f366aac87f44b2

260 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

The Workbook_Open macro is obfuscated and uses GetObject to launch a WMI process, indicating an attempt to execute arbitrary code. The script reconstructs the WMI path "winmgmts:\\.\root\cimv2:Win32_Process" and "winmgmts:\\.\root\cimv2:Win32_ProcessStartup" to create a new process, likely for downloading and executing a secondary payload. The obfuscated nature and the use of WMI for process creation are strong indicators of malicious intent.

Heuristics 6

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.
Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER

Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
Workbook_Open macro high OLE_VBA_WBOPEN

Workbook_Open macro
GetObject call high OLE_VBA_GETOBJ

GetObject call
VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC

Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
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` `0de3d8bc89baaf590b5a71bb820ad5a61e594dcc54bf48b92ff9d81c1bc94bd6`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	8861 bytes
`vbaProject_00.bin` `f06e636e6e21c64b1608c94cbe5a2fbcab3c95d9c1feebc5a134654cc1dcc9e2`	vba-project	OOXML VBA project: xl/vbaProject.bin	65536 bytes

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