Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 a81b71cf0f0ac33c…

MALICIOUS

Office (OLE)

35.5 KB Created: 2020-11-25 10:45:25 Authoring application: Microsoft Excel First seen: 2021-09-16
MD5: 7ef7dd7dd0606545dc46bf26b9ddf1ba SHA-1: 26acaa389e745991788d01c4dd60451d10974040 SHA-256: a81b71cf0f0ac33cb518765f6ced16f03b383faab88c0adf129ab15c80bb767f
140 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 (XLM) macros, specifically an Auto_Open entry. This indicates an attempt to automatically execute code when the workbook is opened. The presence of dangerous formula APIs like RUN suggests the macro is intended to download and execute a second-stage payload, a common technique for malware delivery.

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) 6468 bytes
SHA-256: fb6b55cc202492b3f5831032f2de0ae54d2f9d8c0fbec8621d56933ddf2fda48
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  ADlVZ
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!I150 
' 0018     27 LABEL : Cell Value, String Constant - cfiBuobRGlKu len=0 
' 0018     25 LABEL : Cell Value, String Constant - chWhYBfcKy len=0 
' 0018     21 LABEL : Cell Value, String Constant - CKYRjw len=0 
' 0018     25 LABEL : Cell Value, String Constant - CZIjwDFssZ len=0 
' 0018     24 LABEL : Cell Value, String Constant - EKcDfVWwR len=0 
' 0018     21 LABEL : Cell Value, String Constant - hpEpnj len=0 
' 0018     26 LABEL : Cell Value, String Constant - hruePkUurjY len=0 
' 0018     22 LABEL : Cell Value, String Constant - iBksNAZ len=0 
' 0018     23 LABEL : Cell Value, String Constant - PCkTLNjt len=0 
' 0018     22 LABEL : Cell Value, String Constant - PCKZrRP len=0 
' 0018     26 LABEL : Cell Value, String Constant - rpygAgGANad len=0 
' 0018     27 LABEL : Cell Value, String Constant - TcHpvcQZytgk len=0 
' 0018     21 LABEL : Cell Value, String Constant - UiAJsn len=0 
' 0018     23 LABEL : Cell Value, String Constant - UooZCdrO len=0 
' 0018     24 LABEL : Cell Value, String Constant - uTkxyrDOS len=0 
' 0018     22 LABEL : Cell Value, String Constant - UWNoNzY len=0 
' 0018     27 LABEL : Cell Value, String Constant - VgkSDYyuOVAo len=0 
' 0018     26 LABEL : Cell Value, String Constant - YiULAAkwogE len=0 
' 0018     24 LABEL : Cell Value, String Constant - YSMGBAwJV len=0 
' 0018     23 LABEL : Cell Value, String Constant - ZyPQBbiz 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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