Malicious RTF — malware analysis report

Static analysis result for SHA-256 2f7025f2fb26ba4c…

MALICIOUS

RTF

4.6 KB First seen: 2020-09-07
MD5: 9ad7feae96f3e55f2bbc7f5a3634b330 SHA-1: 9defbad031be9fbd0824bf078ce9763ad455ccd1 SHA-256: 2f7025f2fb26ba4c9721c32e2d27cc7a391b04fded90b6aa788a973cedeadd81
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 Microsoft Equation Editor. Heuristics indicate the exploitation of CVE-2017-11882, which allows for arbitrary code execution when the embedded object is activated. The presence of \objupdate further suggests an attempt to force OLE object activation. The document body contains only numerical data, providing no further context.

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_off000004f2.bin rtf-objdata-decoded RTF \objdata at offset 0x4F2 1674 bytes
SHA-256: 1eb81b12e63a323e22f272fd7c194de5288a92ae5dfc92c80c091361471bed47

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