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

Static analysis result for SHA-256 c81a1afc4f9e8588…

MALICIOUS

Office (OLE) / .XLS

1.66 MB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel First seen: 2023-06-16
MD5: b12ed68cdbac917994444b5d30d84043 SHA-1: 137fb253ae433cabddfebba9c9e541cc49b8f8ce SHA-256: c81a1afc4f9e8588907d1cdb78b0bb50ab10a5a4cffe2022ad8dfa1e749a6ca2
334 Risk Score

Malware Insights

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

MITRE ATT&CK
T1204.002 User Execution: Malicious File T1566.001 Phishing: Spearphishing Attachment

The file is an Excel spreadsheet containing an embedded Equation Editor object that exploits CVE-2017-11882. This object contains a secondary PDF payload which exhibits suspicious static findings, including external URIs. The ClamAV detection as 'Xls.Downloader.94c25b356b5a6cac-9978798-0' strongly suggests a downloader functionality, likely to fetch and execute further malicious content.

Heuristics 10

  • 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.
  • External URI info PDF_URI
    PDF contains an external URL action
  • 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.
  • 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 http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/pdf/1.3/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • https://www.business.hsbc.com.hk/en-gb/resource-centre/commercial-tariffs
    • https://www.online-banking.business.hsbc.com.hk/portalserver/hsbc/dbbpage/commercial/online/timetable/cutoff

Extracted artifacts 8

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
aa85735bb3f04ce5ef2ca4c5ee2caa5e48e9e2ac158ab25da2a45896449d21b9		 ole-package OLE Ole10Native stream: MBD00494F17/olE10native 1481 bytes
font_00_sfnt_off0001cf26.bin
9a85db95c587691a5874b31b664b687edfec6192fc00b1fd6cbfbbe56ee0e2a8		 pdf-font-stream PDF embedded font (sfnt) at offset 0x1CF26 13936 bytes
font_01_sfnt_off0001f5a1.bin
3c119924dbdaf638dde5d0098e911912b53026a6636c8a487543986d08e96bb1		 pdf-font-stream PDF embedded font (sfnt) at offset 0x1F5A1 13556 bytes
polyglot_child_pdf_off00008400.pdf
caa79e5acbf9bc25bfc921be9a5f0f7c31491d9321ded1278ae1c8f8911500ba		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x8400 1701888 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely
polyglot_child_pdf_off0001da00.pdf
0ce47fbbf06e01c5153f2a512aad834a5ed0d4cafd491af270227180aef4b210		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x1DA00 1614336 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely
polyglot_child_pdf_off00088600.pdf
a0feba41b5192d8768e8f1059a4a5ee319a34d486e4a81c38cb42a118a32fde2		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x88600 1177088 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely
polyglot_child_pdf_off0009dc00.pdf
fba64c907fac82712ab97fefcd30929d23c50003b3a45d3fc5a09b09ee3630fd		 polyglot-child-pdf Secondary PDF body inside ole container at offset 0x9DC00 1089536 bytes
Detection
ClamAV: Xls.Downloader.94c25b356b5a6cac-9978798-0
Obfuscation or payload: unlikely

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