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

Static analysis result for SHA-256 441dc00918b7b3e7…

MALICIOUS

Office (OLE) / .XLSX

46.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-14
MD5: 7a227a913c18631b50740554ba9dc1ff SHA-1: 10af635e3aa055606c137c3f838f1439114045d0 SHA-256: 441dc00918b7b3e76142970597e9a1cd7f8a20762406bbc381906ef91a1363b3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file contains Excel 4.0 macros, specifically an Auto_Open function, which is a known technique for executing malicious code. The macros likely leverage the RUN function to download and execute a second-stage payload from one of the provided URLs. The presence of multiple URLs suggests a downloader or droppper functionality. The critical heuristics for OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN confirm the use of auto-execution and risky API calls within the XLM macro.

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
f02d63843d495ffd8e99f1b7fe5f87a80501a758c9a61d8585f8be9700f36cb3
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7798 bytes