Malicious RTF — malware analysis report

Static analysis result for SHA-256 4f6f649d77352844…

MALICIOUS

RTF

12.4 KB First seen: 2020-07-24
MD5: 11d85c616d43eaf3d7a6f05444518463 SHA-1: e68df2dfea31ff8a63b474b01ee4908ae0f3cada SHA-256: 4f6f649d773528449b9c06e9975a4c91d1847a5f6be4d1a79462bafdf72c5da7
200 Risk Score

Malware Insights

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

The RTF document contains embedded OLE object data that is specifically decoded to exploit the Equation Editor vulnerability (CVE-2017-11882). This exploit is designed to execute arbitrary code, likely leading to the download and execution of a secondary malicious payload. The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics further confirms the automatic activation of the embedded object, facilitating the exploit.

Heuristics 5

  • Decoded Equation Editor payload + PE critical CVE likely RTF_EQUATION_EDITOR
    RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000874.bin rtf-objdata-decoded RTF \objdata at offset 0x874 1785 bytes
SHA-256: bd56d550fa40f7bdc1b8b83125cf26ea86788de54e8fb402b54c28726b4f218d

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