Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 79e6324660653f18…

MALICIOUS

RTF / .DOC

15.8 KB
MD5: 812cd5f88f2beff4247a150e2afd00f7 SHA-1: 75a0cfc0c385fd29e546ed0d1725342eeb2f14be SHA-256: 79e6324660653f18b44d2f771209aff9f2a49511c86d0d31cb4d65fa75204ab8
180 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that triggers the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit allows for the execution of arbitrary code, likely to download and run a secondary payload. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this attack 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 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_off0000072c.bin
eb024ca3fc0c665dac7f9f2c117a2682bca2cfdd5ab12ae73e0962ecd3aba405		 rtf-objdata-decoded RTF \objdata at offset 0x72C 1454 bytes

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