Xls.Downloader.94c25b356b5a6cac-9978798-0 — Office (OLE) / .XLS malware analysis

Static analysis result for SHA-256 723d1d6be0a98527…

MALICIOUS

Office (OLE) / .XLS

1.72 MB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2023-06-20
MD5: 362b19963d60e9594bf6fa7a96ec8566 SHA-1: b055b9b0e8bb494eb5374499430cc27403453610 SHA-256: 723d1d6be0a985275ff93c97bb9531b1288ad0bbd948b910e7f40c7447200850
330 Risk Score

Malware Insights

Xls.Downloader.94c25b356b5a6cac-9978798-0 · confidence 95%

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

The sample is an Excel file containing a malicious Equation Editor OLE object, identified as CVE-2017-11882. This object is used to embed and execute a secondary PDF payload. ClamAV detections confirm this is a downloader, likely leveraging the embedded PDF to fetch and execute further malicious content.

Heuristics 8

  • Equation Editor Ole10Native payload — CVE-2017-11882 critical CVE likely CVE_2017_11882_EQUATION_OLE10NATIVE
    An embedded Microsoft Equation 3.0 object (CLSID 0002CE02-0000-0000-C000-000000000046) carries an Ole10Native packager stream instead of the normal Equation Native/MTEF data. This is the weaponized Equation Editor RCE delivery shape used by CVE-2017-11882 / CVE-2018-0802 maldocs. The payload (font-record overflow + shellcode) is frequently encrypted and the stream name case-scrambled to evade scanners, but an Equation object holding an Ole10Native stream has no benign use.
  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Contains Equation Editor object — related to CVE-2017-11882 / CVE-2018-0802 exploitation, but CLSID presence alone is not the malformed MTEF exploit primitive.
  • Secondary embedded PDF body has suspicious static findings critical POLYGLOT_CHILD_PDF_STATIC_TRIAGE
    A valid PDF body was found at a nonzero offset inside another container and its carved contents matched PDF exploit or lure heuristics. This catches polyglots where the top-level magic routes to ZIP/OLE while a PDF reader or downstream parser opens the hidden PDF payload.
  • ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.94c25b356b5a6cac-9978798-0
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • x86 GetPC stub (CALL $+5; POP EBX) high SC_GETPC_CALL
    x86 GetPC stub (CALL $+5; POP EBX)
  • VBA project contains no executable statements low OLE_VBA_MACROS
    Document contains a VBA project, but extracted modules only contain attributes/options/comments and no executable statements.
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
7f506327609c082af1cd37dde23bc2c71a000f7d1ef530b6abb66775040a7673		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 1206 bytes
ole10native_00.bin
f3f742fcac83274a7a56184ef61a817aa4e7ff7465adc9dd1b9d90e4a4a2c469		 ole-package OLE Ole10Native stream: MBD00668A48/oLe10NAtIve 1516 bytes
stream_001_off00000960.bin
2998a126f4fa11ceb265371a5f7968ec18bc4692a32631a544232dc74040021f		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x960 252488 bytes
polyglot_child_pdf_off00008600.pdf
bde1c3d0ea6f3d41008fac395eff6a95dc591746b67937f9aebc9e82c97a2d5d		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x8600 1766912 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely
polyglot_child_pdf_off0002b200.pdf
078fd085d998029514837d4316b21ed81807ea8d94f7ed0a2917da333a41a176		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x2B200 1624576 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely
polyglot_child_pdf_off00098c00.pdf
c036e6becd0ee2d5f7ebfadd22ccd24768ca7c1120bcd564a4419279baa649f0		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x98C00 1175552 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely

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