Office (OLE) / .XLSX malware analysis — malicious · 0c856e57da034a89

MALICIOUS

Office (OLE) / .XLSX

38.0 KB Created: 2021-05-03 10:10:40 Authoring application: Microsoft Excel

MD5: 0d69e4f684735cf4f187659ee0882fd8 SHA-1: 55a52f6971084224e3030b76cd44d13b0203b749 SHA-256: 0c856e57da034a8943b4065297d075365090d9eb925abb7ba74dd3df9acefc1f

200 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The file contains a Workbook_Open macro that triggers obfuscated VBA code. This code utilizes CreateObject, Shell, and exec functions, indicating an attempt to download and execute a secondary payload. The obfuscated nature and auto-execution suggest a malicious downloader. The presence of a Workbook_Open macro strongly implies delivery via spearphishing attachment.

Heuristics 5

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
CreateObject call high OLE_VBA_CREATEOBJ

CreateObject 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 macros detected medium OLE_VBA_MACROS

Document contains VBA macro code

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `4af0a1dded3bd3a3913ecbd8a96d0a84bbeff7ec6ffdd2cc8d8015f877b31e18`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	5005 bytes

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