Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 35c17a5e5fb5bed5…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:44:52 Authoring application: Microsoft Excel First seen: 2021-09-17
MD5: 48e2245642b4bfbedff60d06790acab1 SHA-1: ecc471dfd71138fbc4a420c08bb8be1bf9657851 SHA-256: 35c17a5e5fb5bed522d95a46f11f23bdd103289f83d9f7f9b6b7e6209dd7a519
140 Risk Score

Malware Insights

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

This Excel file contains Excel 4.0 (XLM) macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of dangerous formula APIs like RUN suggests the macro is designed to execute arbitrary commands. The macro sheet likely serves to download and execute a second-stage payload, a common technique for initial execution and further compromise.

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) 6582 bytes
SHA-256: 17383a44a2267c8250f3c9ea99de7ff08e07ef5b4f99e58a67cd7f3cb8e249cd
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     16 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  NmBhGao
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!C184 
' 0018     24 LABEL : Cell Value, String Constant - becJEPaDJ len=0 
' 0018     22 LABEL : Cell Value, String Constant - BxMCwTQ len=0 
' 0018     27 LABEL : Cell Value, String Constant - EparpsdfWPaK len=0 
' 0018     21 LABEL : Cell Value, String Constant - FiWaEp len=0 
' 0018     24 LABEL : Cell Value, String Constant - hXrEXrGUz len=0 
' 0018     26 LABEL : Cell Value, String Constant - iQyxnSCjiHv len=0 
' 0018     22 LABEL : Cell Value, String Constant - NSubGuP len=0 
' 0018     20 LABEL : Cell Value, String Constant - OjXpu len=0 
' 0018     21 LABEL : Cell Value, String Constant - pdxHzS len=0 
' 0018     22 LABEL : Cell Value, String Constant - qGxCeZX len=0 
' 0018     23 LABEL : Cell Value, String Constant - rHIsddOQ len=0 
' 0018     27 LABEL : Cell Value, String Constant - RwPEywtRNVOp len=0 
' 0018     20 LABEL : Cell Value, String Constant - Tyaew len=0 
' 0018     22 LABEL : Cell Value, String Constant - tyFzlDx len=0 
' 0018     25 LABEL : Cell Value, String Constant - uzWzFVtaGq len=0 
' 0018     26 LABEL : Cell Value, String Constant - VdzbVowztcw len=0 
' 0018     25 LABEL : Cell Value, String Constant - vTMzBtAoOT len=0 
' 0018     21 LABEL : Cell Value, String Constant - WcEmec len=0 
' 0018     27 LABEL : Cell Value, String Constant - WOupStBKxIBc len=0 
' 0018     25 LABEL : Cell Value, String Constant - XXjcDGkVvz 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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