Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 da4aa9780808e5f2…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:46:31 Authoring application: Microsoft Excel First seen: 2021-10-16
MD5: bc716a3e176b6fd85e1d10cb5a7acbd4 SHA-1: 15c41c72601ff02c30d57886dd5fad260288c2c3 SHA-256: da4aa9780808e5f28cf6fef63912c4c0ffe439548938acb509938d575ee11f05
140 Risk Score

Malware Insights

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

The file is an Excel document containing Excel 4.0 macros, specifically an Auto_Open function. This function is designed to execute automatically when the workbook is opened, indicating a malicious intent to run arbitrary code. The presence of dangerous formula APIs further supports this. The macro sheet itself contains a large amount of obfuscated data, suggesting it's used to hide the malicious payload.

Heuristics 3

  • 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.
  • XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN
    Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
  • 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) 6636 bytes
SHA-256: 626c7c3ef94214b0bed1e9dac76cb7406bff0f24b7f56fcee6b6b48cdd3c94ff
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     19 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  jFlZgZYxcI
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!E166 
' 0018     24 LABEL : Cell Value, String Constant - CQbfyZJMH len=0 
' 0018     25 LABEL : Cell Value, String Constant - FgOQyMRgeW len=0 
' 0018     27 LABEL : Cell Value, String Constant - gpOgXYvfRRBu len=0 
' 0018     25 LABEL : Cell Value, String Constant - gslHQpBDEV len=0 
' 0018     22 LABEL : Cell Value, String Constant - gXFqRJA len=0 
' 0018     23 LABEL : Cell Value, String Constant - iOQWNeCm len=0 
' 0018     26 LABEL : Cell Value, String Constant - jjNIgDPRApf len=0 
' 0018     27 LABEL : Cell Value, String Constant - jVKJDGHjSxER len=0 
' 0018     21 LABEL : Cell Value, String Constant - KEoaoi len=0 
' 0018     20 LABEL : Cell Value, String Constant - LCBKU len=0 
' 0018     25 LABEL : Cell Value, String Constant - odxxedbNZj len=0 
' 0018     20 LABEL : Cell Value, String Constant - OpFIy len=0 
' 0018     27 LABEL : Cell Value, String Constant - pwDZBjEWGzlS len=0 
' 0018     22 LABEL : Cell Value, String Constant - REJONLT len=0 
' 0018     24 LABEL : Cell Value, String Constant - rXTwMZxMw len=0 
' 0018     20 LABEL : Cell Value, String Constant - SVyMd len=0 
' 0018     21 LABEL : Cell Value, String Constant - TATrri len=0 
' 0018     26 LABEL : Cell Value, String Constant - UGDfnbaKWmF len=0 
' 0018     24 LABEL : Cell Value, String Constant - vduhoOZsi len=0 
' 0018     26 LABEL : Cell Value, String Constant - voBlFSJeroL len=0 
' 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
'
... (truncated)

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