Malicious RTF — malware analysis report

Static analysis result for SHA-256 1f231429b852477a…

MALICIOUS

RTF

1.22 MB Created: 2020-04-05 21:42:00 First seen: 2020-05-25
MD5: f45173de1236ab2171d66d1a74b74018 SHA-1: fa89b5adaca2757b88875cb3cc389179d5638e97 SHA-256: 1f231429b852477ae050090c1d3d67bc40df06c87a563a6e9e4de3bc09a1cf6a
182 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that triggers CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This vulnerability allows for arbitrary code execution when the object is activated, likely leading to the download and execution of a secondary payload. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this exploit.

Heuristics 6

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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://schemas.microsoft.com/office/word/2003/wordml In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00002e54.bin rtf-objdata-decoded RTF \objdata at offset 0x2E54 120530 bytes
SHA-256: c15fd627ee9c92c0f8d0100906689a4a345edba59aa686bc6e5d8c1185c48893

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