Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 301a513b8cd504bf…

MALICIOUS

Office (OLE)

35.5 KB Created: 2020-11-25 10:40:27 Authoring application: Microsoft Excel First seen: 2021-10-02
MD5: d2b51782cd2705c4612893dd809b1228 SHA-1: b86d89caaea34032f49ccc3436f9113ce2e58418 SHA-256: 301a513b8cd504bfd30977079b102f7bd3972dcae11ae3cf6f5b57507b8d5fd9
140 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro sheet that contains an Auto_Open entry, indicating it will execute automatically upon opening. Heuristics confirm the presence of dangerous formula APIs like RUN, suggesting the macro is designed to execute arbitrary code. The macro sheet itself contains obfuscated strings and truncated data, but the presence of the Auto_Open function is a strong indicator of malicious intent, likely 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) 6530 bytes
SHA-256: e273e35256fb9b2233e7e1f3c679ffda75c2ccf512d19051501765b257f3690a
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     17 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  MCCUOUSd
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!F134 
' 0018     20 LABEL : Cell Value, String Constant - ELKrl len=0 
' 0018     21 LABEL : Cell Value, String Constant - GNWSKE len=0 
' 0018     23 LABEL : Cell Value, String Constant - hlYpywUX len=0 
' 0018     26 LABEL : Cell Value, String Constant - hsHoKyLEYVe len=0 
' 0018     20 LABEL : Cell Value, String Constant - jvIQT len=0 
' 0018     22 LABEL : Cell Value, String Constant - lXbsuqI len=0 
' 0018     24 LABEL : Cell Value, String Constant - MHtXJqohl len=0 
' 0018     21 LABEL : Cell Value, String Constant - mWLsZb len=0 
' 0018     26 LABEL : Cell Value, String Constant - oXPJxhKpEfh len=0 
' 0018     24 LABEL : Cell Value, String Constant - pHXijnPFJ len=0 
' 0018     24 LABEL : Cell Value, String Constant - QmbXGkYby len=0 
' 0018     24 LABEL : Cell Value, String Constant - RcjbLPCFe len=0 
' 0018     24 LABEL : Cell Value, String Constant - tRyCkfqsn len=0 
' 0018     22 LABEL : Cell Value, String Constant - uGpmmqo len=0 
' 0018     25 LABEL : Cell Value, String Constant - VcwTClZgtG len=0 
' 0018     27 LABEL : Cell Value, String Constant - VOLRXOElyftI len=0 
' 0018     23 LABEL : Cell Value, String Constant - XxvLFSTC len=0 
' 0018     27 LABEL : Cell Value, String Constant - yxFEHGnqIVVL len=0 
' 0018     22 LABEL : Cell Value, String Constant - zjEHUFQ len=0 
' 0018     25 LABEL : Cell Value, String Constant - zPeGzTmjsI 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  
... (truncated)

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