Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c0cd92af5fa0886e…

MALICIOUS

Office (OLE)

36.0 KB Created: 2020-11-25 10:45:55 Authoring application: Microsoft Excel First seen: 2021-05-22
MD5: b5744c2188ee38ea1070148d810e32e9 SHA-1: df07e89f8cfa7afa94ae6c340c7733c752581bdc SHA-256: c0cd92af5fa0886e2d3f866a36e02e2a5965996e329e73782069fe29fdb7344d
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 macros, specifically an Auto_Open function. This function is known to be used for executing arbitrary code, often to download and run further malicious content. The critical heuristics indicate the presence of dangerous formula APIs within the XLM macro, strongly suggesting an attempt to execute code. No specific IOCs like URLs or hashes were directly extracted from the macro content itself, hence the family is unknown.

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) 6470 bytes
SHA-256: 5777bc0a075eee6b06802709c697f9093da827cd5abf56622b3adb96fe79b995
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     15 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  mhRMJA
' 0018     22 LABEL : Cell Value, String Constant - AibTUKo len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  Sheet!H130 
' 0018     26 LABEL : Cell Value, String Constant - CGNfaQkpldj len=0 
' 0018     25 LABEL : Cell Value, String Constant - ErUeKcjoJw len=0 
' 0018     22 LABEL : Cell Value, String Constant - FXcZHlb len=0 
' 0018     23 LABEL : Cell Value, String Constant - GtbcYVPq len=0 
' 0018     26 LABEL : Cell Value, String Constant - IhbTAcuYTfK len=0 
' 0018     21 LABEL : Cell Value, String Constant - jedEIP len=0 
' 0018     27 LABEL : Cell Value, String Constant - JqEIptpWqNgY len=0 
' 0018     27 LABEL : Cell Value, String Constant - lnHNEyePcCMJ len=0 
' 0018     21 LABEL : Cell Value, String Constant - lnouVt len=0 
' 0018     27 LABEL : Cell Value, String Constant - lrlLmjUxgvfp len=0 
' 0018     22 LABEL : Cell Value, String Constant - nRszjek len=0 
' 0018     24 LABEL : Cell Value, String Constant - OPEOgwWWu len=0 
' 0018     21 LABEL : Cell Value, String Constant - smERFK len=0 
' 0018     23 LABEL : Cell Value, String Constant - uELVtODo len=0 
' 0018     27 LABEL : Cell Value, String Constant - uTdCbOpGgjMa len=0 
' 0018     22 LABEL : Cell Value, String Constant - WbYUYZb len=0 
' 0018     26 LABEL : Cell Value, String Constant - xJzaZxJtEIs len=0 
' 0018     20 LABEL : Cell Value, String Constant - ycJAK len=0 
' 0018     22 LABEL : Cell Value, String Constant - zlcIyzq 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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