Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 bf55535aa7c9aa03…

MALICIOUS

Office (OLE)

37.0 KB Created: 2020-11-27 11:43:09 Authoring application: Microsoft Excel First seen: 2020-12-25
MD5: a100cfd677589e8833367310e923bf06 SHA-1: 7806bb07c1aff53fdbf3b9adbda66d42e931e0ab SHA-256: bf55535aa7c9aa03b2f9723fc5cb72c8a24d8b7b30cafa0d6c6623aa73db2e85
140 Risk Score

Malware Insights

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

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by critical heuristic firings for OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN. The presence of an Auto_Open defined name suggests that the macro will execute automatically upon opening the workbook. This is a common technique for delivering malicious payloads, likely involving the execution of dangerous formula APIs to download and run 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) 6918 bytes
SHA-256: e7cf33c341c1797019eaf7f7a66c22cdc32487d30bd7e044b3b1cbfe60c46044
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 -  AhfnJwXRC
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!D150 
' 0018     24 LABEL : Cell Value, String Constant - BGGyFQbWc len=0 
' 0018     27 LABEL : Cell Value, String Constant - bQVJazpamfcp len=0 
' 0018     26 LABEL : Cell Value, String Constant - BrShCLHCKZp len=0 
' 0018     25 LABEL : Cell Value, String Constant - CctrALbXYa len=0 
' 0018     24 LABEL : Cell Value, String Constant - EKCnybMIU len=0 
' 0018     25 LABEL : Cell Value, String Constant - ibTiohQukh len=0 
' 0018     24 LABEL : Cell Value, String Constant - IGXaihFKI len=0 
' 0018     23 LABEL : Cell Value, String Constant - IYHhGeDB len=0 
' 0018     20 LABEL : Cell Value, String Constant - IYIfL len=0 
' 0018     23 LABEL : Cell Value, String Constant - KXKzvsoh len=0 
' 0018     21 LABEL : Cell Value, String Constant - lhoROi len=0 
' 0018     22 LABEL : Cell Value, String Constant - lIfjyBM len=0 
' 0018     22 LABEL : Cell Value, String Constant - LYtGSZd len=0 
' 0018     26 LABEL : Cell Value, String Constant - nByCTxSERey len=0 
' 0018     23 LABEL : Cell Value, String Constant - pPRCcTLX len=0 
' 0018     27 LABEL : Cell Value, String Constant - psLHJsuuMZJi len=0 
' 0018     24 LABEL : Cell Value, String Constant - raGtZzTCO len=0 
' 0018     25 LABEL : Cell Value, String Constant - RhKpOkaCLC len=0 
' 0018     22 LABEL : Cell Value, String Constant - TbNvGdy len=0 
' 0018     24 LABEL : Cell Value, String Constant - xzpXQZTNn 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

... (truncated)

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