Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 a3d6644b0039ed5a…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-27 11:45:49 Authoring application: Microsoft Excel First seen: 2021-07-02
MD5: 871d101a02d0c6bd53492ebed2ac8988 SHA-1: 598376f86e7edb52c8a8b46fdd79d9c58e32b1a1 SHA-256: a3d6644b0039ed5a6f542a3e6a7b8a839581d62017266beeadbb39350647ce5b
140 Risk Score

Malware Insights

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

The sample is an Excel 4.0 macro-enabled workbook. Critical heuristics indicate the presence of an Auto_Open macro, which is a common technique for executing malicious code upon opening the document. The macro sheet contains a large amount of obfuscated data, suggesting it is designed to download and execute 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) 6574 bytes
SHA-256: c075be4b1d975691f4dcf3cb5e3909cc7b8ea0e78f835861d20983093fa60bc2
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     13 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  UhBI
' 0018     25 LABEL : Cell Value, String Constant - amqpDOmSjZ len=0 
' 0018     22 LABEL : Cell Value, String Constant - aPqPHhS len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!B192 
' 0018     20 LABEL : Cell Value, String Constant - BcypF len=0 
' 0018     23 LABEL : Cell Value, String Constant - ccgkiDQW len=0 
' 0018     21 LABEL : Cell Value, String Constant - eNcYwn len=0 
' 0018     20 LABEL : Cell Value, String Constant - hVCzE len=0 
' 0018     27 LABEL : Cell Value, String Constant - jhSvEjHVIhDx len=0 
' 0018     21 LABEL : Cell Value, String Constant - jxHgEP len=0 
' 0018     24 LABEL : Cell Value, String Constant - kniyEKhlX len=0 
' 0018     20 LABEL : Cell Value, String Constant - kwvAV len=0 
' 0018     20 LABEL : Cell Value, String Constant - MEabz len=0 
' 0018     26 LABEL : Cell Value, String Constant - NOhTPFLJrSj len=0 
' 0018     22 LABEL : Cell Value, String Constant - NPjwRKt len=0 
' 0018     20 LABEL : Cell Value, String Constant - oaCyT len=0 
' 0018     25 LABEL : Cell Value, String Constant - prMsAvHWFZ len=0 
' 0018     20 LABEL : Cell Value, String Constant - rtorq len=0 
' 0018     25 LABEL : Cell Value, String Constant - sjpydgzFFe len=0 
' 0018     27 LABEL : Cell Value, String Constant - SVPtBcohTDdO len=0 
' 0018     23 LABEL : Cell Value, String Constant - UwuZuieP len=0 
' 0018     27 LABEL : Cell Value, String Constant - YiClCDodwwyC 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 LABELSST :
... (truncated)

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