Malicious RTF — malware analysis report

Static analysis result for SHA-256 75975b538373a3ac…

MALICIOUS

RTF

364.9 KB First seen: 2019-04-18
MD5: f8c6cd1e1ddd09fa7a69752cb3b572df SHA-1: 8bcfd88c539bf741deb9c1fb96b416e8ed4133a3 SHA-256: 75975b538373a3acfd9455d42fa7eb13647d6cbbf1b669c10b232d7434486974
180 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 Equation Editor. High-severity heuristics indicate the activation of CVE-2017-11882, a known vulnerability that allows for arbitrary code execution. This suggests the file is designed to exploit this vulnerability upon opening, likely delivered as a spearphishing attachment.

Heuristics 5

  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 2251 bytes
SHA-256: 42d5e5da03a927ba1f3671a2c70b2990717343697874e87bfa12ae103cb97325

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