Malicious RTF — malware analysis report

Static analysis result for SHA-256 eda8614acc9eb0eb…

MALICIOUS

RTF

19.5 KB First seen: 2020-09-07
MD5: 770249431df924c8e4a3e8032cf31714 SHA-1: 9a8f8d56f89fcae951967229119c84277038022b SHA-256: eda8614acc9eb0eb5a3b75b366dee17137d14f16e554c84c6e6f378270b47c06
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 forces OLE activation, confirming the exploitation vector.

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_off000017ad.bin rtf-objdata-decoded RTF \objdata at offset 0x17AD 1983 bytes
SHA-256: c81993419d2b3ae5667a60a3497050ddd0d2bcda7f3f482a942a78b9c7ad7f5b

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