Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 0111f37e35555485…

MALICIOUS

Office (OOXML) / .XLSM

437.4 KB Created: 2021-07-28 10:37:27 UTC Authoring application: Microsoft Excel 12.0000
MD5: 7384fe86962d57142927ac7cd6ec5500 SHA-1: 0feb556579d4bf9940b625193e16e80595a27eab SHA-256: 0111f37e35555485821187a6179bc95f4687c3220feacff90d6542238ba88d7b
208 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.003 Windows Command Shell T1204.002 Malicious File

The critical heuristic 'Obfuscated auto-exec VBA loader' indicates a malicious macro. The Workbook_Open macro executes obfuscated code that constructs a string using Environ and Cells values, writes it to a file named '\getRangeValueDefault5130.sct', and then uses 'Wscript.Shell' to execute this file via 'mshta'. This indicates the Excel file is a downloader for a second-stage payload.

Heuristics 6

  • 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 project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Environ() call (env variable access) low OLE_VBA_ENVIRON
    Environ() call (env variable access)

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
caeedb2f6ff6d4b838c22ca48741e0d798200667352650ef8daf35b82e4d7f2e		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 1151 bytes
vbaProject_00.bin
13e3ada3bd8a75c7f0cf29ad1a5395597beb6f2c2cebbb6937209d2a1ea40487		 vba-project OOXML VBA project: xl/vbaProject.bin 9216 bytes

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