Xls.Downloader.bf2d2f272706032b-9980309-0 — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 42d0082e585e06f7…

MALICIOUS

Office (OLE) / .XLS

432.0 KB Created: 2021-02-03 15:28:44 Authoring application: Microsoft Excel First seen: 2022-11-28
MD5: b370036e80b83499b4bc486137b893c4 SHA-1: b4d424e2da518fe193346809be62e63c44e97fdd SHA-256: 42d0082e585e06f70971897e9c1b7a5f40b92e39889082c648ad7d3ff66905f9
422 Risk Score

Malware Insights

Xls.Downloader.bf2d2f272706032b-9980309-0 · confidence 95%

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 workbook that impersonates DocuSign to lure the user into enabling macros. Upon enabling, it is designed to download and execute a second-stage payload from the URL https://server-panelllx-9.gq/Myfile.exe. The presence of Auto_Open and dangerous formula APIs in the XLM macro sheet, along with the ClamAV detection, strongly indicates downloader functionality.

Heuristics 10

  • 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) Auto_Open + macro sheet critical OLE_XLM_AUTOOPEN
    Workbook contains an Auto_Open / Auto_Close defined name together with an Excel 4.0 macro sheet — the canonical XLM auto-execution shape used by malware families such as Emotet and QakBot.
  • 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.
  • URL reconstructed from XLM cell array (1 URL) critical OLE_XLM_CELL_ARRAY_URL
    Excel 4.0 macro sheet stages its payload URL across the BIFF8 Shared String Table (one quoted-char SST entry concatenated with & at runtime) or across individual numeric cells (one ASCII charcode per cell). The reconstructed URL is invisible to literal-bytes URL extraction because it is never contiguous in the workbook stream. URLs were recovered by walking the BIFF8 record stream and decoding SST entries plus LABELSST/RK/NUMBER cells.
  • ClamAV: Xls.Downloader.bf2d2f272706032b-9980309-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.bf2d2f272706032b-9980309-0
  • VBA macros detected medium OLE_VBA_MACROS
    Document contains VBA macro code
  • 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
  • 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://server-panelllx-9.gq/Myfile.exe
    • https://server-panelllx-9.gq/Myfile.exe�
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/photoshop/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/tiff/1.0/
    • http://ns.adobe.com/exif/1.0/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt
0db271a63e699246c73fb8c3af1384d51f8ab34eaad410458ac3d83518be8241		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 6360 bytes
macros.bas
544daaabe44d28a0d90032cc3a030b8ea0c58bb49ed123e4b89277098cd2b245		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 726 bytes

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