Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 f42cba5e93c27e43…

MALICIOUS

Office (OLE) / .XLS

239.0 KB Created: 2020-11-20 17:59:00 Authoring application: Microsoft Excel
MD5: 8ebe9946f98a51a3167d5c9eda5939f0 SHA-1: 5ba41b16e4936a9a6271aff04e79ad1b53d2528e SHA-256: f42cba5e93c27e43bf02f3efebee0488c4509904e6642d2fe8c5f3fa1066e260
148 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that uses dangerous functions like RUN. The truncated script excerpt shows a formula that appears to construct a command to download and execute a payload using Net.WebClient. This suggests the file is a downloader. The VBA project contains no executable statements, indicating the primary malicious logic resides in the XLM macros.

Heuristics 4

  • 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.
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
1bd4e99c3593ebf8cacfb1d15df7b972f65af5b9ecfe4b65292c2cc176632530		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 2433 bytes
macros.bas
fed365d3401536fb63e11d0a36cc7c35338c0a8c74a96fb254c46366ad6287cd		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 642 bytes

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