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

Static analysis result for SHA-256 c0848753a5147220…

MALICIOUS

Office (OLE) / .XLS

135.0 KB Created: 2020-06-01 21:18:31 Authoring application: Microsoft Excel
MD5: ae52e72f8f925efb12c045cc335fb08e SHA-1: 0acd29fad8715aaec9e33132eec918512d8adb99 SHA-256: c0848753a51472209624f631955a9ad9ff39d5b9fc9686c6f0da0530239916e8
200 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1218.011 Signed Binary Proxy Execution: Rundll32 T1105 Ingress Tool Transfer T1059.003 Command and Scripting Interpreter: Windows Command Shell T1059.001 Command and Scripting Interpreter: PowerShell

The sample contains Excel 4.0 macros (Auto_Open) that leverage dangerous functions like RUN. It references ShellExecuteA and URLDownloadToFileA APIs, indicating an intent to download and execute external content. The script reconstructs the URL "https://tlanddissipate.at/3/rbs.dll" and uses regsvr32.exe or rundll32.exe to execute it, likely to download and run a second-stage payload. The creation of directories like C:\PyKPMXo suggests staging for the downloaded payload.

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://tlanddissipate.at/3/rbs.dll

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
25b4d7f6e73e4b6b57e5ba1d37c5d8acb12bda01728e82126f5f952f0b90fdfb		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 52521 bytes

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