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

Static analysis result for SHA-256 86290d58e392856a…

MALICIOUS

Office (OLE) / .XLSX

35.5 KB Created: 2020-11-25 10:32:43 Authoring application: Microsoft Excel
MD5: cbcff7bb32c45a05fef84dcc97c58279 SHA-1: e05444cf542521b7d35ca6491d386b62385b2227 SHA-256: 86290d58e392856a07b284ae735c484e458feb55c8404618bc7ca4e849531498
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 function, which is a known technique for executing malicious code upon opening the workbook. The presence of the 'RUN=0' API in the macro sheet indicates the intent to execute a command. While the specific command is not fully detailed in the provided evidence, the Auto_Open function strongly suggests a downloader or initial execution stage for further malicious activity. The document body contains garbled text, offering no contextual clues about the lure.

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
0f410ec81dc5981dc3a16968e6e89c1a9323338b80f7922094ad9202b45f937e
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6637 bytes