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

Static analysis result for SHA-256 cd28baeb9b0cda87…

MALICIOUS

Office (OLE) / .XLS

43.0 KB Created: 2020-10-14 08:50:46 Authoring application: Microsoft Excel
MD5: 3d38a7d97c23bb4a4ada41287a3504a3 SHA-1: 985ce5b0c556a174532b28c98a5d1afacf9c8c1d SHA-256: cd28baeb9b0cda873358bf15911925bb77039577d064bbd6d202338f92f6c23d
140 Risk Score

Malware Insights

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

The file contains Excel 4.0 macros, specifically an Auto_Open defined name, which is a critical finding. The macros utilize dangerous formula APIs, including the RUN function, indicating an intent to execute arbitrary code. This is a common technique for delivering secondary payloads. No specific IOCs like URLs or hashes were extracted, but the presence of the Auto_Open macro and the use of the RUN function strongly suggest a malicious downloader or dropper.

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
34ea6a3de2f9be0b43d1e19e6d4981fe2c66aad937eb20b231de4883eae7a697
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 8963 bytes