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

Static analysis result for SHA-256 aa1de269e9f52cde…

MALICIOUS

Office (OLE) / .XLSX

36.0 KB Created: 2020-11-27 11:39:32 Authoring application: Microsoft Excel
MD5: 41d4d1c35a627bad8e050e561d6b7e4e SHA-1: 11f552f39b714d27313c38fc3999a3d13db290b2 SHA-256: aa1de269e9f52cde3206897924851965444a149e487ff14d27e575d1423f6611
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical indicator of malicious intent. The presence of the Auto_Open function suggests that the macro will execute automatically upon opening the workbook. The heuristics indicate the use of dangerous formula APIs, including the RUN function, which is commonly used to execute arbitrary commands or download and run additional payloads. No specific URLs or hashes were extracted, but the technique itself is highly suspicious.

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
466078e0de7b14209fbab271a1883ebe5a264baf10dfb8762658b4e459d3627b
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6894 bytes