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

Static analysis result for SHA-256 4ecb21d893c4232b…

MALICIOUS

Office (OLE) / .XLS

525.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2021-05-29
MD5: 4ae7613df2463fe7e89ea12f0b46e611 SHA-1: 0c4131e0c2c427a8f6607b11dffe01e99f6c88f0 SHA-256: 4ecb21d893c4232b6d0e16e534a51429c866e2c6d75aeb477826787df5f3e8d2
142 Risk Score

Malware Insights

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

The sample is an Excel 4.0 macro sheet (XLM) that contains a lure to enable macros. The document body contains obfuscated strings that appear to be related to downloading files and executing them via rundll32. The embedded URLs are likely used to fetch and execute a second-stage payload. The confidence is reduced due to the obfuscated nature of the script and lack of specific family indicators.

Heuristics 5

  • XLM Auto_Open workbook with payload URL or enable-content lure critical OLE_XLM_AUTOOPEN_PAYLOAD_LURE
    Workbook contains an Excel 4.0 macro sheet with Auto_Open / Auto_Close and also exposes a payload URL or enable-content lure in the OLE bytes. This combination is a high-confidence XLM downloader/social-engineering pattern even when formula recovery cannot decode the full macro chain.
  • Excel 4.0 (XLM) macro sheet uses dangerous capability functions high OLE_XLM_DANGEROUS_FN_STATIC
    Workbook contains an Excel 4.0 macro sheet whose formulas reference two or more dangerous capability functions (e.g. CALL into a Win32 API such as URLDownloadToFile, EXEC to launch a process, REGISTER an external DLL procedure, or FWRITE/FOPEN to drop a file) with an Auto_Open / Auto_Close auto-execution name. This is the canonical XLM downloader/dropper shape and is recovered directly from the BIFF records, so it fires even when the full macro chain cannot be deobfuscated.
  • 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.
  • 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 https://aravindanavada.com/AHt5r3T0VSlq/solo.html In document text (OLE body)
    • https://mrcrgroup.com/sOyQynNJYBY/solo.htmlIn document text (OLE body)

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