Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b1b9e59ef5c70f85…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:38:26 Authoring application: Microsoft Excel First seen: 2021-07-07
MD5: bcd7a1f97b590fef4c97f30c285c137e SHA-1: f94e7d0cedf15862a1ed19e10448717212062fb2 SHA-256: b1b9e59ef5c70f85d77cb0224be1be6523894aa68c4e73b0fb26f30e4d204c1b
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open defined name, which is a known method for executing malicious code. The macro sheet contains a reference to a dangerous formula API, suggesting it is designed to run arbitrary commands. The presence of obfuscated strings and the overall structure point towards a downloader or initial execution stage for a more complex attack.

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) 6577 bytes
SHA-256: 7ae7c2c60131db5893d52f289d57cd7001418087618261a276ef712d74a4fbf2
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     17 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  lrFSaLZo
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!D183 
' 0018     22 LABEL : Cell Value, String Constant - HAAkxOq len=0 
' 0018     21 LABEL : Cell Value, String Constant - IJBhsh len=0 
' 0018     20 LABEL : Cell Value, String Constant - IjxmF len=0 
' 0018     24 LABEL : Cell Value, String Constant - ijyFSWwdE len=0 
' 0018     25 LABEL : Cell Value, String Constant - IjZaxaAqaT len=0 
' 0018     20 LABEL : Cell Value, String Constant - ixMOL len=0 
' 0018     21 LABEL : Cell Value, String Constant - kPxIiN len=0 
' 0018     25 LABEL : Cell Value, String Constant - LHZWYJgsCj len=0 
' 0018     26 LABEL : Cell Value, String Constant - MFOXBlZnBmG len=0 
' 0018     22 LABEL : Cell Value, String Constant - miozsKy len=0 
' 0018     21 LABEL : Cell Value, String Constant - mKMWbN len=0 
' 0018     21 LABEL : Cell Value, String Constant - pvdOlG len=0 
' 0018     23 LABEL : Cell Value, String Constant - pYSqKwYe len=0 
' 0018     26 LABEL : Cell Value, String Constant - qxfilJpEiNW len=0 
' 0018     25 LABEL : Cell Value, String Constant - TuUfAEMZgq len=0 
' 0018     22 LABEL : Cell Value, String Constant - uNZIHqa len=0 
' 0018     25 LABEL : Cell Value, String Constant - vLCjglULAi len=0 
' 0018     21 LABEL : Cell Value, String Constant - VSkiWx len=0 
' 0018     26 LABEL : Cell Value, String Constant - xUTyoxtMLOn len=0 
' 0018     23 LABEL : Cell Value, String Constant - zGLJYhwI 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
' 00fd     10 LABEL
... (truncated)

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