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

Static analysis result for SHA-256 82e8764e28de6a77…

MALICIOUS

Office (OLE) / .XLS

272.0 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel
MD5: 7c5ea1db9d29fd2ebd0ac7c65bb3977d SHA-1: c9736ccde23b02bccc415def8d9ff20f783d3cd7 SHA-256: 82e8764e28de6a770f2454e80925f2de358d9910a63138dfc1de0c6df331e003
180 Risk Score

Malware Insights

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

The sample is an Excel 4.0 macro-enabled spreadsheet that impersonates a document signing service like DocuSign to trick the user into enabling macros. The presence of the 'SC_STR_URLDOWNLOAD' and 'OLE_XLM_AUTOOPEN' heuristics, along with the 'URLDownloadToFileA' API call, indicates that the macro attempts to download a second-stage payload from the URL 'd2zjc3191twk8ym.xyz/index.php'. The extracted 'nkfkdsn.exe' suggests the downloaded payload is an executable.

Heuristics 5

  • 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.
  • 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
  • Document signing service impersonation lure medium SE_DOCUSIGN_LURE
    Document impersonates DocuSign, Adobe Sign, or a similar signing service in a signing-request context

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
a3d3cdb345325c3d4854a528125a7497cbe060388705eec0a3c4c39b53ce0ead
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 1187 bytes