Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f633ed8e9502815c…

MALICIOUS

RTF / .DOC

13.0 KB First seen: 2022-10-05
MD5: fa590fa2cba422717a06d5e5e660b3b7 SHA-1: 9b28e4be6b833277797722bce7a3e1730f887493 SHA-256: f633ed8e9502815ca959b98fe3169d2a89d7c56859ac67803d675260c59873ac
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566.001 Spearphishing Attachment T1059.005 Visual Basic

The sample is an RTF file containing a malicious OLE object, specifically exploiting CVE-2017-11882 via the Equation Editor. The document body contains a lure instructing the user to 'Enable editing', a common tactic for macro-based malware. The embedded OLE object is designed to activate automatically, likely leading to the execution of a second-stage payload.

Heuristics 6

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \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
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001639.bin
a7fd64a047d219407cd4ba56a275ce888b5ec0f313222bb6a9b62c0ee9e96487		 rtf-objdata-decoded RTF \objdata at offset 0x1639 1388 bytes

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