Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 115dc53146a7d23d…

MALICIOUS

RTF / .DOC

1.81 MB First seen: 2022-04-08
MD5: 389cbc1dcce453cad602782f104a3079 SHA-1: 4e9f7e8d6fbfe945f8ac38d3781651f2d7867468 SHA-256: 115dc53146a7d23dd6463d87d240c853d03811a2036da4e99bfeb67e502bdae5
220 Risk Score

Malware Insights

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

The RTF file contains embedded OLE object data, specifically related to Microsoft Equation Editor. Heuristics indicate a critical vulnerability, CVE-2017-11882, is likely being exploited to execute a native payload. The presence of ".objupdate" further suggests an attempt to force OLE activation. The large amount of hex-encoded data within the OLE object is likely hiding the actual malicious payload.

Heuristics 5

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1896KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000012a2.bin
7162083990cb0eb27dfcf08117c3a1ba66224dbb8ea74b6cd18575b8caa3782a		 rtf-objdata-decoded RTF \objdata at offset 0x12A2 948413 bytes

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