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

Static analysis result for SHA-256 39c867b6a4935692…

MALICIOUS

Office (OLE) / .XLS

45.0 KB Created: 2020-11-03 08:10:44 Authoring application: Microsoft Excel
MD5: b169d53b327f390545087b7b52c2e853 SHA-1: 8ae4df9a9b43f08fbfeed67cde945274866d44a0 SHA-256: 39c867b6a4935692dccfbe1d4ed8113bffea25f72a7a471f562d8848e3cd7ed6
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1566.001 Spearphishing Attachment

The critical OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN heuristics indicate the presence of an Excel 4.0 macro sheet with an Auto_Open entry that utilizes dangerous functions like RUN. This strongly suggests the macro is designed to execute arbitrary commands upon opening the spreadsheet. The macro sheet itself contains numerous string constants, but the specific commands or URLs are not directly visible in the provided excerpt. The primary attack vector is likely spearphishing with a malicious attachment.

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
d30d2a6b7c00bd4ffeea2c997ea391c9fa7db9c6c14e8392aafdacc575d1ce6c
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 13739 bytes