Xls.Downloader.Trojan-aa0b8f388d8573cd — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 e288c853afd9e636…

MALICIOUS

Office (OOXML) / .XLSX

778.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-07-19
MD5: 2134ce57c884ab2e6dceeee3cb30673e SHA-1: a06dd52b802a6dd4bdee4b57f0de6da70bc3c128 SHA-256: e288c853afd9e6369767d14553ebd6a471d2adb2a2e5b6b80f487d8e3d84d7d2
160 Risk Score

Malware Insights

Xls.Downloader.Trojan-aa0b8f388d8573cd · confidence 95%

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

The sample is an Excel file containing an embedded OLE object, identified as an Equation Editor. This object exhibits anomalies in its Ole10Native stream, suggesting it carries a malicious payload. ClamAV detection confirms this, classifying it as Xls.Downloader.Trojan-aa0b8f388d8573cd. The embedded object and its anomalous stream are the primary indicators of malicious intent.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/Pm00u.G1mYZC 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
4e831e530779bbc129db18b30b59d70372a31404d47e75dba55689664aaff2d6		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Pm00u.G1mYZC 891392 bytes
ooxml_oleobject_00_ole10native_00.bin
4f0fa2b7bf4d15e6d66511b5e044ac8533f55a60a22d1bd52ed1a9b2c572ecc2		 ole-package OOXML xl/embeddings/Pm00u.G1mYZC Ole10Native stream: oLe10nATivE 882042 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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