Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 a810fe997e38630c…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:35:06 Authoring application: Microsoft Excel First seen: 2021-09-16
MD5: c66a36969b9c4c69af83768bf76e6711 SHA-1: 8077add7e321c9b5a966c8cf4495330cb1fa5388 SHA-256: a810fe997e38630c98b2098ade72f1b4f432a6fb38a5f7c5e5b4d355df4b6902
140 Risk Score

Malware Insights

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

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry point. This suggests the file is designed to automatically execute code when opened, likely to download and run a second-stage payload. The macro sheet contains references to dangerous formula APIs, further supporting malicious intent.

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) 6530 bytes
SHA-256: 0161a84e36219ad8a46284495dd2d6fcae948df080a5bd4e5d5a3eb8e7925860
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 -  HsOIr
' 0018     26 LABEL : Cell Value, String Constant - ahnbTnXVlhj len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!H142 
' 0018     25 LABEL : Cell Value, String Constant - cCvqbQhcbv len=0 
' 0018     25 LABEL : Cell Value, String Constant - CThzKcxpfG len=0 
' 0018     20 LABEL : Cell Value, String Constant - iuLPd len=0 
' 0018     23 LABEL : Cell Value, String Constant - iXOmmfCA len=0 
' 0018     25 LABEL : Cell Value, String Constant - lnQcnJusck len=0 
' 0018     21 LABEL : Cell Value, String Constant - lufhHs len=0 
' 0018     20 LABEL : Cell Value, String Constant - MfcxY len=0 
' 0018     27 LABEL : Cell Value, String Constant - nfUyizZlFNLV len=0 
' 0018     25 LABEL : Cell Value, String Constant - OwonpWJYZN len=0 
' 0018     23 LABEL : Cell Value, String Constant - pXIaWbmt len=0 
' 0018     27 LABEL : Cell Value, String Constant - SBkpXrKYWKcl len=0 
' 0018     22 LABEL : Cell Value, String Constant - svYkiFf len=0 
' 0018     23 LABEL : Cell Value, String Constant - tDFEjzOQ len=0 
' 0018     22 LABEL : Cell Value, String Constant - twnqMys len=0 
' 0018     26 LABEL : Cell Value, String Constant - VLoDngoEebo len=0 
' 0018     25 LABEL : Cell Value, String Constant - wcteBtOZfm len=0 
' 0018     24 LABEL : Cell Value, String Constant - wHnzsRral len=0 
' 0018     25 LABEL : Cell Value, String Constant - XEssYBkTEN len=0 
' 0018     27 LABEL : Cell Value, String Constant - ziSFpMmrlYyN 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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