Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 5ecf24186a69169a…

MALICIOUS

Office (OLE)

36.5 KB Created: 2020-11-27 11:37:58 Authoring application: Microsoft Excel First seen: 2021-07-07
MD5: 8434812ac5205b7f13780ade4c6a51b0 SHA-1: 266158cc1648c5543e6e0044c86ad2b1484af1f4 SHA-256: 5ecf24186a69169a843825beca7b44aea38dc4b9212ea7e3d3d558da07b99bd7
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. The critical heuristic OLE_XLM_AUTOOPEN_DEFINEDNAME indicates the presence of an Auto_Open entry, which is automatically executed when the workbook is opened. The OLE_XLM_DANGEROUS_FN heuristic further confirms that dangerous formula APIs, including 'RUN', are used within these macros. This strongly suggests the macros are designed to execute arbitrary code, likely to download and run a second-stage 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) 6678 bytes
SHA-256: d27ac3c71fa4da3e43d8e912d3d792bc0f99cd2fde11739c20914e15ed8ec992
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     12 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  azE
' 0018     27 LABEL : Cell Value, String Constant - asmcYHAoLDzL len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!F165 
' 0018     24 LABEL : Cell Value, String Constant - biIklRWFk len=0 
' 0018     20 LABEL : Cell Value, String Constant - BRkCn len=0 
' 0018     26 LABEL : Cell Value, String Constant - caUDlfIISdA len=0 
' 0018     24 LABEL : Cell Value, String Constant - eYemnXlQr len=0 
' 0018     20 LABEL : Cell Value, String Constant - flNLT len=0 
' 0018     22 LABEL : Cell Value, String Constant - fPHbpWz len=0 
' 0018     26 LABEL : Cell Value, String Constant - iCJiTczXZlS len=0 
' 0018     22 LABEL : Cell Value, String Constant - IfkZkeN len=0 
' 0018     23 LABEL : Cell Value, String Constant - jtsWrIHk len=0 
' 0018     22 LABEL : Cell Value, String Constant - leQXjwX len=0 
' 0018     27 LABEL : Cell Value, String Constant - NKzWcnyOQPPu len=0 
' 0018     26 LABEL : Cell Value, String Constant - qniymAQEEVW len=0 
' 0018     21 LABEL : Cell Value, String Constant - WIrVLc len=0 
' 0018     22 LABEL : Cell Value, String Constant - WriXRnJ len=0 
' 0018     24 LABEL : Cell Value, String Constant - xcIkwKQgR len=0 
' 0018     26 LABEL : Cell Value, String Constant - XcPbzklmjhs len=0 
' 0018     22 LABEL : Cell Value, String Constant - xeCBkCi len=0 
' 0018     27 LABEL : Cell Value, String Constant - YtLOhpCRaMRz len=0 
' 0018     22 LABEL : Cell Value, String Constant - ZdoQsHA 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    
... (truncated)

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