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

Static analysis result for SHA-256 a5952a9d55da4fba…

MALICIOUS

Office (OLE) / .XLS

112.0 KB Created: 2020-06-04 15:18:10 Authoring application: Microsoft Excel
MD5: 88d4eaa1fca6f7065942cd0fc7df841a SHA-1: c057bb22cbb788f78727f92fb5ea61e771b133fd SHA-256: a5952a9d55da4fbad5aa38694221f3bbf1ae892a958f92118f8b78167a842d63
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer T1059.003 Windows Command Shell

The sample contains Excel 4.0 (XLM) macros, specifically an Auto_Open macro that utilizes dangerous functions like ShellExecuteA and URLDownloadToFileA. The script attempts to download a payload from 'https://destgrena.at/3/tsk.dll' and execute it using tools like regsvr32.exe or rundll32.exe. The presence of these functions and the download/execution chain strongly indicate a downloader or droppper functionality.

Heuristics 6

  • Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD
    Reference to URLDownloadToFile API
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • XLM Auto_Open with dangerous formula APIs high 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.
  • Visible LOLBin command execution instruction high SE_LOLBIN_RUN_COMMAND
    Document contains instructions or visible command text involving Windows script/execution tools such as PowerShell, mshta, cmd, rundll32, or regsvr32
  • 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://destgrena.at/3/tsk.dll

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
456ed4b930c9e68d29a09d702cf3a7b00eed118ad9ac8720cc4f9a494dd6c8fa		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 31686 bytes

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