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

Static analysis result for SHA-256 12de42545f812387…

MALICIOUS

Office (OOXML) / .XLSX

871.8 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-09-02
MD5: a7fdd9045ed043a314033fb32e5b17ba SHA-1: 96009a63df2a0352adf4c422bb36f0e8a41dc027 SHA-256: 12de42545f81238728010f5c504351691ce5692575edf2f43e92c315071bb62c
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1566 Phishing T1566.002 Spearphishing Attachment

The sample is an Excel file containing an embedded OLE object, specifically identified as an Equation Editor object. This object carries a payload-like Ole10Native stream, indicating it's designed to exploit vulnerabilities within the Equation Editor. ClamAV detection confirms this as a downloader trojan, likely leveraging the Equation Editor vulnerability to execute a malicious payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/bW.c72l5l 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
a5938c649b2b458e637af78d416e6c110fcd9e31293b7f5237aae86551e6f019		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/bW.c72l5l 1016832 bytes
ooxml_oleobject_00_ole10native_00.bin
9c54dba7af0c87ac71fd0cf9ee729e370fe5ab5fdfbd34942d81eef212af58d6		 ole-package OOXML xl/embeddings/bW.c72l5l Ole10Native stream: ole10NAtivE 1006217 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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