Xls.Downloader.af2fa5c5d0587870-9978799-0 — Office (OOXML) malware analysis

Static analysis result for SHA-256 b846d18b75abb146…

MALICIOUS

Office (OOXML)

1.15 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: f8cc1f9031c21d0a975d5197f5ca073f SHA-1: 22b2b035beb26d6d7864c194a86c7f266e374692 SHA-256: b846d18b75abb146a171080b94d55010749c218c1c631fad3590ac0c0e68f73f
170 Risk Score

Malware Insights

Xls.Downloader.af2fa5c5d0587870-9978799-0 · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The critical ClamAV detection and high-severity heuristics for OLE Equation Editor objects indicate the file is a downloader. The presence of an anomalous Ole10Native stream within the Equation Editor object suggests it carries a payload designed to be executed. The file likely exploits a vulnerability in the Equation Editor to achieve initial execution and download a secondary payload.

Heuristics 6

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is an exploit-shaped Equation/OLE payload container seen in malicious OOXML samples. It is not assigned to a specific CVE unless the MTEF/Equation Native primitive also matches.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • 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.day.com/dam/1.0
    • http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/tiff/1.0/

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
5e4cb9f5d6d891d950bf250d19118f638a875ff34cb7fc3422111b740797a1f9		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 926720 bytes
ooxml_oleobject_00_ole10native_00.bin
475394c7faf9ef4191d48fa06d52e0c3394c2ed3f62a5495194d4a3e0f824c84		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLE10naTIvE 916927 bytes
ooxml_oleobject_01.bin
1589fe5dca85f26dec581006bf5018c1e2cea74ec6da7486add355fe47e1bc15		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 10240 bytes
ooxml_oleobject_01_ole10native_00.bin
59fb77315591a55324873430963abffa12244adc4996302250a87d8a758a5796		 ole-package OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native 8667 bytes
ooxml_oleobject_02.bin
d491abddffae594960153518e1baa000a78fa97b0ed6d11e02d8a1ec7719851e		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Microsoft_Office_Word_Macro-Enabled_Document1.docm 122513 bytes
emf_00.emf
2aaefdd887b07c0c00d1e36b7fd463600254a4f424010532673862db93fd83bc		 ooxml-emf OOXML EMF part: xl/media/image5.emf 7608 bytes
emf_01.emf
778a99e829bea81b0a10813f268b41a560372c8cdda02b13e558aa6e98ab8dfd		 ooxml-emf OOXML EMF part: xl/media/image4.emf 648132 bytes

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