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

Static analysis result for SHA-256 87aef5406dbda03a…

MALICIOUS

Office (OLE) / .XLS

165.0 KB Created: 2020-02-27 10:23:09 Authoring application: Microsoft Excel First seen: 2022-07-21
MD5: 809ec8b9cc10b2348578ad69779f3d0b SHA-1: d6c522ab1e635fac17331c62eb1bc338dbcb4091 SHA-256: 87aef5406dbda03a138f1e239db619d949eba9cca546da5956bf3d7ae2652677
202 Risk Score

Malware Insights

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

The file is an Excel 4.0 macro-enabled spreadsheet that contains an Auto_Open macro. This macro is designed to execute a series of commands that reconstruct and download a payload from the URL 'https://gfhudnjv.xyz/vjd7f2js'. The use of Auto_Open and the reconstruction of a URL from cell data are strong indicators of a downloader or initial access stage.

Heuristics 5

  • 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.
  • URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://gfhudnjv.xyz/vjd7f2js

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a644f931803b80e5785d4b01693b40402254588ef12534e46ce327cdf216fbdd		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 46231 bytes

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