Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 5daf1e45bf8b5e55…

MALICIOUS

Office (OLE)

35.5 KB Created: 2020-11-27 11:41:32 Authoring application: Microsoft Excel First seen: 2021-06-28
MD5: 5940a9e272c5cb7868ef2761e09df903 SHA-1: ace0f84580b3c54711e9a7a5d1bb097531aaf1b7 SHA-256: 5daf1e45bf8b5e552bd87ab89b74e134fc38cad901888af9ae765a1f2f1606b8
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 entry, which is a common technique for executing malicious code upon opening the document. The macro sheet contains a reference to a dangerous formula API, suggesting it is designed to perform actions beyond typical spreadsheet operations. The presence of obfuscated strings and the structure of the macro sheet point towards a downloader or initial execution stage.

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) 6728 bytes
SHA-256: f0c6e251be5a2302a2c39b1f710badd56d6e7eacded5cd5a69b4009e07c20d10
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     16 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  beXINCg
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!C157 
' 0018     27 LABEL : Cell Value, String Constant - BaufWsNzEgkD len=0 
' 0018     26 LABEL : Cell Value, String Constant - BHcOvoWgdwF len=0 
' 0018     26 LABEL : Cell Value, String Constant - BPWibFeqpvm len=0 
' 0018     20 LABEL : Cell Value, String Constant - cpHHs len=0 
' 0018     25 LABEL : Cell Value, String Constant - eGDsJxIjov len=0 
' 0018     23 LABEL : Cell Value, String Constant - HDtjXbAH len=0 
' 0018     27 LABEL : Cell Value, String Constant - hXRNBiLAlLRF len=0 
' 0018     26 LABEL : Cell Value, String Constant - JedLEDAzjZS len=0 
' 0018     25 LABEL : Cell Value, String Constant - JiseszAICJ len=0 
' 0018     20 LABEL : Cell Value, String Constant - lqaaa len=0 
' 0018     21 LABEL : Cell Value, String Constant - NeWUFU len=0 
' 0018     25 LABEL : Cell Value, String Constant - oESrDCKpvX len=0 
' 0018     20 LABEL : Cell Value, String Constant - PAaqp len=0 
' 0018     25 LABEL : Cell Value, String Constant - PqynlfCTfj len=0 
' 0018     27 LABEL : Cell Value, String Constant - qcIOoISbhMFs len=0 
' 0018     25 LABEL : Cell Value, String Constant - QfvqbZlWab len=0 
' 0018     22 LABEL : Cell Value, String Constant - qhHmKIC len=0 
' 0018     23 LABEL : Cell Value, String Constant - UqnMvEQP len=0 
' 0018     27 LABEL : Cell Value, String Constant - zAydEbVNfycq len=0 
' 0018     20 LABEL : Cell Value, String Constant - zGsGs 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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