Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 5b061bcc593476ca…

MALICIOUS

Office (OOXML) / .XLSX

848.2 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-08-29
MD5: 492302c2a95f0c7ace097f125386ef12 SHA-1: 4664cb8e523ea613553dcdf25cce6f4c0c71b921 SHA-256: 5b061bcc593476ca93aaf0ba35e5b7accbf22cf4271e0b89fd18ce6901788f7e
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1559.001 Component Object Model Hijacking

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous size and entropy, strongly suggesting exploitation. ClamAV detection confirms this as a downloader trojan.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/wpk.bj contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • ClamAV: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0
  • 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

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
09028fea3e4a61c9ca79026534eb3039b8d72ba3e8414174d33f01b4183bb019		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/wpk.bj 991232 bytes
ooxml_oleobject_00_ole10native_00.bin
29958894cbec54b4531e0754ce716146ce0a169948152b3f7d65fbbe42c002c4		 ole-package OOXML xl/embeddings/wpk.bj Ole10Native stream: ole10NATIVE 980648 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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