Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 23c2c40eeb403db2…

MALICIOUS

RTF / .DOC

3.4 KB First seen: 2022-12-13
MD5: 9c0000ee7368897c003cff9a4fa0e949 SHA-1: b8c222e53206cf4fc2aa67cee57d0f2163606eaa SHA-256: 23c2c40eeb403db286dd89b0a4628ab9d0510cb51070b7e2e41b880511a46281
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The ".objupdate" directive forces the activation of this embedded object, which is designed to execute arbitrary code. This is a common technique for initial access, often delivered via spearphishing attachments.

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_off00000075.bin
364790cba1c9641b291571d432eaf915ed07d8656727839f6c1ac61c3eefbafb		 rtf-objdata-decoded RTF \objdata at offset 0x75 1639 bytes

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