Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c36d5060ce649c20…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:24:47 Authoring application: Microsoft Excel First seen: 2021-06-13
MD5: 1dbb7bd0bab8121f7ecedf158c16af3d SHA-1: bc744f0762cc631b4e9cb15fd746b19e6777c6f9 SHA-256: c36d5060ce649c20a98bb7876daaaa07f8228396bd5a573cbde723fa65c199cc
140 Risk Score

Malware Insights

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

The file is an Excel document containing Excel 4.0 (XLM) macros. Critical heuristics indicate the presence of an Auto_Open defined name, which is a common technique for automatically executing malicious code upon opening the workbook. The macro sheet also utilizes dangerous formula APIs, specifically the RUN function, to execute arbitrary code, likely leading to the download and execution of 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) 6509 bytes
SHA-256: c9ee52c5a58de98ba531bf98408f837e90e78db78c0fba71d0692c46cbccde5f
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 -  rKVDGJKy
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!D182 
' 0018     25 LABEL : Cell Value, String Constant - bfeJGxyyuV len=0 
' 0018     24 LABEL : Cell Value, String Constant - ClijQgnlJ len=0 
' 0018     24 LABEL : Cell Value, String Constant - emolcUYHI len=0 
' 0018     24 LABEL : Cell Value, String Constant - fIfhHUKnb len=0 
' 0018     26 LABEL : Cell Value, String Constant - GFskuilOzHq len=0 
' 0018     27 LABEL : Cell Value, String Constant - gotbuleqKJew len=0 
' 0018     22 LABEL : Cell Value, String Constant - hDkLbOh len=0 
' 0018     20 LABEL : Cell Value, String Constant - KWaSf len=0 
' 0018     22 LABEL : Cell Value, String Constant - mCUSMef len=0 
' 0018     20 LABEL : Cell Value, String Constant - nawMW len=0 
' 0018     20 LABEL : Cell Value, String Constant - oUXbH len=0 
' 0018     21 LABEL : Cell Value, String Constant - piNRpm len=0 
' 0018     27 LABEL : Cell Value, String Constant - RBhRnqXsxBjZ len=0 
' 0018     25 LABEL : Cell Value, String Constant - SRlAFOcQxy len=0 
' 0018     20 LABEL : Cell Value, String Constant - twNdT len=0 
' 0018     27 LABEL : Cell Value, String Constant - veDSNBHbtOkI len=0 
' 0018     23 LABEL : Cell Value, String Constant - VgWMrgpB len=0 
' 0018     24 LABEL : Cell Value, String Constant - yUgilGIOz len=0 
' 0018     22 LABEL : Cell Value, String Constant - ZlGWxDD len=0 
' 0018     20 LABEL : Cell Value, String Constant - znalX 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     10 L
... (truncated)

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