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

Static analysis result for SHA-256 64578ba1b26d9942…

MALICIOUS

Office (OLE) / .XLS

62.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: ae2ca5fa66c9606fa7afeb869523be58 SHA-1: 30b168ae9a5f6ec26db729b1447afaeacdfde05e SHA-256: 64578ba1b26d9942e0cb0d9a6cec10e44ddff2932fd050febdf0dea23b0e1e46
382 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1203 Exploitation for Client Execution T1105 Ingress Tool Transfer

The sample is an Excel 4.0 (XLM) macro-enabled spreadsheet that contains an Auto_Open macro. This macro is designed to execute dangerous functions like RUN, which is used to download and execute a second-stage payload from the URL http://blog.vokasidev.com/crun20.gif. The presence of a Workbook_Open VBA macro further supports the malicious intent by attempting to close the application, likely to hide its execution. The document body also contains the same URL, reinforcing the download lure.

Heuristics 10

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • 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.
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • 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.
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
  • 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 http://blog.vokasidev.com/crun20.gif
    • http://blog.vokasidev.com/crun20.gif�

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
d4222e1ad83b892546402a65bce1342319760d5f0e17d0c73ae5f07e792beb86		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 9447 bytes
macros.bas
c29faf2da8b6b84c63880f8f3ff09f138acdaa94ad9406cab75b546ae0e54428		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 979 bytes

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