Malicious RTF — malware analysis report

Static analysis result for SHA-256 cfe8ea4eaad19fb0…

MALICIOUS

RTF

454.8 KB First seen: 2019-02-26
MD5: f9795fd0fa5a0b4f6e07990f3ce77d8e SHA-1: b7a6416c9026244b4a4e0f4afc7660ef4c82aa4b SHA-256: cfe8ea4eaad19fb01ad1efd2606d0f50ae0c4a67b97ecf9306dc8d810db64bf8
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, a known vulnerability that allows for arbitrary code execution when the Equation Editor is activated. This strongly suggests the file is designed to exploit this vulnerability to deliver a secondary payload.

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_off00000a6e.bin rtf-objdata-decoded RTF \objdata at offset 0xA6E 27609 bytes
SHA-256: dc12e27c3da153b3e82c0267f3c577b83e2a9cde00461291775b4c53426246d3

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