Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 1615c46ae8e9b2f2…

MALICIOUS

Office (OLE)

144.5 KB Created: 2011-02-11 19:24:00 Authoring application: Microsoft Excel First seen: 2020-07-24
MD5: ae6cec0d6053f9dc4f6f93a5615001fc SHA-1: 34639c2f8d2933f7cef1a99b5f3d8996d718e941 SHA-256: 1615c46ae8e9b2f243ed4e124edffeea4cd452fd5a2ad92b496260e1c963ae86
80 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The critical heuristic firing indicates the presence of an Excel 4.0 macro sheet with an Auto_Open defined name, which is a common technique for executing malicious code upon opening the document. The macro sheet itself is heavily obfuscated, but the presence of Auto_Open strongly suggests it is designed to download and execute a second-stage payload. The document body contains only obfuscated strings, providing no direct clues to the payload's purpose.

Heuristics 2

  • Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME
    oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
  • Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN
    Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 82640 bytes
SHA-256: 3f9631bd220acf9537bfa27ac64e576e38c1fdc99d37a18e984693d00574282f
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     18 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  gdy0rV3wC
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open hidden len=7 ptgRef3d  Sheet!DC3796 
' 0018     29 LABEL : Cell Value, String Constant -     hidden len=11 ptgArea3d  *INCOMPLETE FORMULA PARSING* Remaining, unparsed expression: b'\x00\x00\xa3\x0e,\x0f\x0b\x00\x0b\x00'
' 0018     29 LABEL : Cell Value, String Constant - NqzRiEB hidden len=7 ptgRef3d  Sheet!DC3796 
' 0018     29 LABEL : Cell Value, String Constant -     hidden len=11 ptgArea3d  *INCOMPLETE FORMULA PARSING* Remaining, unparsed expression: b'\x00\x00\x13\x0fo\x0f\\\x00\\\x00'
' 0018     29 LABEL : Cell Value, String Constant -         hidden len=7 ptgRef3d  Sheet!DC3798 
' 0018     30 LABEL : Cell Value, String Constant -      hidden len=11 ptgArea3d  *INCOMPLETE FORMULA PARSING* Remaining, unparsed expression: b'\x00\x00\xc9\x0e\x1a\x0fc\x00c\x00'
' 0018     30 LABEL : Cell Value, String Constant -          hidden len=7 ptgRef3d  Sheet!DC3800 
' 0018     28 LABEL : Cell Value, String Constant -        hidden len=7 ptgRef3d  Sheet!DC3801 
' 0018     30 LABEL : Cell Value, String Constant -          hidden len=7 ptgRef3d  Sheet!DC3802 
' 0018     29 LABEL : Cell Value, String Constant -     hidden len=11 ptgArea3d  *INCOMPLETE FORMULA PARSING* Remaining, unparsed expression: b'\x00\x00\xfa\x0e\x90\x0f)\x00)\x00'
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String
... (truncated)

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