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

Static analysis result for SHA-256 debf78ac913e3b76…

MALICIOUS

Office (OLE) / .XLS

856.5 KB Created: 2019-10-22 07:10:34 Authoring application: Microsoft Excel
MD5: 02bebda14734b392c40e86a08717e140 SHA-1: 95a6a416f682a9d254e76ec38ade01ce241b3366 SHA-256: debf78ac913e3b76debc7c4745d1e9ff858d6f3392ad02db78eb18408ac4beaf
400 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1059.005 Visual Basic

The sample is an Excel 4.0 macro-enabled spreadsheet. The Auto_Open macro executes a command that invokes cmd.exe to run bitsadmin for downloading a file, followed by a PowerShell execution. This indicates a downloader or dropper functionality. The ClamAV detection name 'Xls.Dropper.Agent-8424546-0' further supports this assessment.

Heuristics 9

  • 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.
  • ClamAV: Xls.Dropper.Agent-8424546-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-8424546-0
  • Suspicious cmd.exe invocation with execution flag high SC_STR_CMD
    Suspicious cmd.exe invocation with execution flag
  • Reference to PowerShell high SC_STR_POWERSHELL
    Reference to PowerShell
  • Reference to bitsadmin (download) high SC_STR_BITSADMIN
    Reference to bitsadmin (download)
  • LOLBin token sequence in document text high SE_LOLBIN_RUN_COMMAND
    Extracted document text contains a Windows script/execution tool name (PowerShell, mshta, cmd, rundll32, regsvr32, …) within 220 characters of a dangerous flag, command verb, or URL. This is a visible 'run this' instruction in HTML/PDF/RTF lure bodies, or — in macro-laden Office files — the macro's own string-pool entries appearing adjacent in extracted text.
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • 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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
f7e3b1c66f0228de06b1b05bf43a702e99c84ab3ea9bdfdc83d8b27c10c4189a		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1984 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 shell/COM execution token(s). Carved macro source contains an auto-exec entry point and execution/download terms.

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