Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 3db9536d2d513241…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-27 11:44:28 Authoring application: Microsoft Excel First seen: 2021-06-13
MD5: 631c67f4b162d1a9a207e60c6a66b9a3 SHA-1: 9aa1e2748bd195d25b3f017ed14bec9b62c2b8c0 SHA-256: 3db9536d2d513241c12dec08b1a985e523c41afd0144ed9b22fa793e72817a52
140 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 macros, specifically an Auto_Open macro. This macro is designed to execute arbitrary code, indicated by the critical heuristic 'XLM_DANGEROUS_FN' firing with 'RUN=0'. The macro sheet itself contains obfuscated data, suggesting an attempt to hide its malicious functionality. The primary purpose is 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) 6895 bytes
SHA-256: f0ebb185de3fe86a66a2cddf296a59e72a1685406f438277966839a482257f59
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     20 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  gGaWoNgrzfO
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!E174 
' 0018     23 LABEL : Cell Value, String Constant - DCqPdruL len=0 
' 0018     22 LABEL : Cell Value, String Constant - favljbO len=0 
' 0018     27 LABEL : Cell Value, String Constant - GCIkvNWMlMsF len=0 
' 0018     21 LABEL : Cell Value, String Constant - GYnTzB len=0 
' 0018     23 LABEL : Cell Value, String Constant - hEoXzyiy len=0 
' 0018     26 LABEL : Cell Value, String Constant - hMZBtBdxQgV len=0 
' 0018     23 LABEL : Cell Value, String Constant - jGiqSSOc len=0 
' 0018     21 LABEL : Cell Value, String Constant - MuxdZM len=0 
' 0018     23 LABEL : Cell Value, String Constant - nSBJQGzQ len=0 
' 0018     25 LABEL : Cell Value, String Constant - nYyuNkWuZm len=0 
' 0018     27 LABEL : Cell Value, String Constant - oBoaFyKpmtuS len=0 
' 0018     27 LABEL : Cell Value, String Constant - oPFcuJlbDzmM len=0 
' 0018     25 LABEL : Cell Value, String Constant - SxEaEqlFLH len=0 
' 0018     20 LABEL : Cell Value, String Constant - tMjbh len=0 
' 0018     21 LABEL : Cell Value, String Constant - UxInCL len=0 
' 0018     22 LABEL : Cell Value, String Constant - VaolVCJ len=0 
' 0018     24 LABEL : Cell Value, String Constant - vbmeOyxlG len=0 
' 0018     26 LABEL : Cell Value, String Constant - XlGZFUCMoLS len=0 
' 0018     27 LABEL : Cell Value, String Constant - xRlbqZfSKALF len=0 
' 0018     26 LABEL : Cell Value, String Constant - ztzmavOnEEJ 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/ 
... (truncated)

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