Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c4bacd5def03bca6…

MALICIOUS

Office (OLE)

36.5 KB Created: 2020-11-25 10:40:07 Authoring application: Microsoft Excel First seen: 2021-09-24
MD5: dd30e3a90aab7244dc99f0901751deff SHA-1: d5f38a4e6b070753bd86b81b3a2417289084b2f6 SHA-256: c4bacd5def03bca6ecdf96ba1d60fe794222798cd37b8bcece455abe426a7da7
140 Risk Score

Malware Insights

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

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open entry, which is a known method for executing malicious code upon opening the document. The macro sheet contains a reference to a dangerous formula API, specifically RUN, suggesting it is designed to execute commands. This points to a macro-based downloader attack pattern.

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) 6690 bytes
SHA-256: fece332a25422d60c979c0ee535d19c296c7a7db39422ed25eb8d7c79c61c98c
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     18 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  LWAOGIzDL
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!B159 
' 0018     26 LABEL : Cell Value, String Constant - BFayEsGqTAG len=0 
' 0018     26 LABEL : Cell Value, String Constant - bMlDSsHdwHM len=0 
' 0018     25 LABEL : Cell Value, String Constant - czouztdlYX len=0 
' 0018     23 LABEL : Cell Value, String Constant - DBWKnjYq len=0 
' 0018     27 LABEL : Cell Value, String Constant - fkTisAEfgTVc len=0 
' 0018     21 LABEL : Cell Value, String Constant - fomrOC len=0 
' 0018     24 LABEL : Cell Value, String Constant - gmHhbLMwW len=0 
' 0018     22 LABEL : Cell Value, String Constant - hgmUHBz len=0 
' 0018     27 LABEL : Cell Value, String Constant - kdmmwhyCJKni len=0 
' 0018     21 LABEL : Cell Value, String Constant - kRGLUl len=0 
' 0018     21 LABEL : Cell Value, String Constant - KyCNSI len=0 
' 0018     22 LABEL : Cell Value, String Constant - npDtHdo len=0 
' 0018     24 LABEL : Cell Value, String Constant - nqkaNcMMB len=0 
' 0018     26 LABEL : Cell Value, String Constant - OSbppZwRGqd len=0 
' 0018     20 LABEL : Cell Value, String Constant - pgXIK len=0 
' 0018     26 LABEL : Cell Value, String Constant - RJIdyswoUQk len=0 
' 0018     25 LABEL : Cell Value, String Constant - UBVCMQGLvq len=0 
' 0018     27 LABEL : Cell Value, String Constant - VBrQheLufrwL len=0 
' 0018     27 LABEL : Cell Value, String Constant - WagzpLYIXJgK len=0 
' 0018     25 LABEL : Cell Value, String Constant - XvUWCuQatM 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 Consta
... (truncated)

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