Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 392b34093e2b4673…

MALICIOUS

RTF / .DOC

13.7 KB First seen: 2022-06-27
MD5: 3465b4385a22631e2f6a2ddda6ab8083 SHA-1: b2f320b782e35b2e8feece58f423a36a5955ee60 SHA-256: 392b34093e2b4673f8a0a4b89c84fe8a5ba01ff8b9e03cb0f1e444d94905fd1b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File Execution: User Execution

The sample is an RTF document containing an embedded OLE object that exploits CVE-2017-11882 through the Equation Editor. The critical heuristic 'RTF_EQUATION_EDITOR' and related high-confidence firings directly indicate this vulnerability is being leveraged. The embedded object is likely used to download and execute a secondary payload, a common technique for initial access.

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 2 \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_off00002012.bin
df32a3b73dbe992314213f40a9623ece07183e9302ac1a3783dcb9093d3e46b6		 rtf-objdata-decoded RTF \objdata at offset 0x2012 2180 bytes

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