Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 b6c8fe4d9ae0b8c8…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-27 11:40:52 Authoring application: Microsoft Excel First seen: 2021-07-02
MD5: 7c5caa8fd3ae38387497b0f81cbe3bcf SHA-1: acf0b8d9b14cbce404e51758f05e7c85987472c8 SHA-256: b6c8fe4d9ae0b8c82d2274ec03fe6fe6f41ad23020a8f908a740f9b3b60bcbcc
140 Risk Score

Malware Insights

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

The file is an Excel document containing Excel 4.0 (XLM) macros. The critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for executing malicious code upon opening the workbook. The macro sheet contains references to dangerous formula APIs, specifically 'RUN', suggesting it is designed to execute arbitrary commands. The document body contains obfuscated text, likely part of the macro's execution flow or a lure. The primary function of the XLM macro is to execute a command, which is highly indicative of a downloader or initial execution stage for further malicious activity.

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) 6856 bytes
SHA-256: 35e188cbca4cc353c887b49f36284407d1a8b94740db9d9a8a8ffc3dc3817c9a
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 -  eOhUcxCNta
' 0018     27 LABEL : Cell Value, String Constant - AbLPWWGeCFko len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!A129 
' 0018     22 LABEL : Cell Value, String Constant - cXvDloP len=0 
' 0018     25 LABEL : Cell Value, String Constant - dcwhtVIipF len=0 
' 0018     25 LABEL : Cell Value, String Constant - eThFukNuNf len=0 
' 0018     22 LABEL : Cell Value, String Constant - FieUSgd len=0 
' 0018     25 LABEL : Cell Value, String Constant - HdLUlLNhaD len=0 
' 0018     27 LABEL : Cell Value, String Constant - iUBVrXKNIyfd len=0 
' 0018     24 LABEL : Cell Value, String Constant - kKzbHLgXJ len=0 
' 0018     20 LABEL : Cell Value, String Constant - lbten len=0 
' 0018     26 LABEL : Cell Value, String Constant - mowWzzlvMWb len=0 
' 0018     20 LABEL : Cell Value, String Constant - nlstv len=0 
' 0018     21 LABEL : Cell Value, String Constant - olgSvy len=0 
' 0018     21 LABEL : Cell Value, String Constant - RoIqIW len=0 
' 0018     26 LABEL : Cell Value, String Constant - rQlftpfdBPG len=0 
' 0018     21 LABEL : Cell Value, String Constant - SHKVgn len=0 
' 0018     27 LABEL : Cell Value, String Constant - TmHBZcTBvwsh len=0 
' 0018     24 LABEL : Cell Value, String Constant - VdHOlzNdy len=0 
' 0018     27 LABEL : Cell Value, String Constant - wFeSiJERWLxO len=0 
' 0018     26 LABEL : Cell Value, String Constant - XqjUobXoFCf len=0 
' 0018     23 LABEL : Cell Value, String Constant - YWatuTXT 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/ S
... (truncated)

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