Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 edff360acfdac0f9…

MALICIOUS

Office (OLE)

98.5 KB Created: 2018-12-19 10:42:12 Authoring application: Microsoft Excel First seen: 2021-04-10
MD5: 01ff777b9c887d231464416cdaabcd4e SHA-1: f3aa6d0e90a0289fb932dd10f292bcf5e10fe6b5 SHA-256: edff360acfdac0f9a0e5b66f593e07744db5e053b29b69a459b6f28ebedd0b42
262 Risk Score

Heuristics 6

  • ClamAV: Xls.Dropper.Agent-7143117-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-7143117-0
  • 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.
  • URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime), across individual numeric cells (one ASCII charcode per cell), or split across multi-char fragment cells a download formula concatenates by reference (=A1&A2&… / CONCATENATE(...)). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries, LABELSST/RK/NUMBER cells, and FORMULA cell-reference concatenation in token order.
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://92.38.135.134/dom2 Referenced by macro

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) 1530 bytes
SHA-256: cabfcd7c40e4ae03ac140da3b43c59b223708082b0c1e9374ce21e88349c269f
Preview script
First 1,000 lines of the extracted script
' 0085      9 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  
' 0085      9 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  
' 0085      9 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, hidden -  
' 0085     12 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  OOO
' 0018     28 LABEL : Cell Value, String Constant - Labos1 len=7 ptgRef3d  !A4 
' 0018     28 LABEL : Cell Value, String Constant - Labos2 len=7 ptgRef3d  !A12 
' 0018     28 LABEL : Cell Value, String Constant - Macro1 len=7 ptgRef3d  !A4 
' 0018     28 LABEL : Cell Value, String Constant - Macro2 len=7 ptgRef3d  !A12 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  !A1 
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 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
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' Sheet,Reference,Formula,Value
'  ,A1,Labos1(),""
'  ,A3,HALT(),""
'  ,A5,Labos2(),""
'  ,A8,RETURN(),""
'  ,A14,EXEC( !A50),""
'  ,A17,RETURN(),""
'  ,A50,"CONCATENATE(A51,A52,G66,A53,A54)",""
'  ,A55,HALT(),""

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