Malicious RTF — malware analysis report

Static analysis result for SHA-256 5b9f6f63c0161cb8…

MALICIOUS

RTF

28.5 KB First seen: 2022-11-14
MD5: ca4e667d605bfc6c33321001fd3810e2 SHA-1: 2116e6e9127c8ddc88400ef884590d26b686a554 SHA-256: 5b9f6f63c0161cb8b7d37d5f11735350775ebb74d4895ce403a1d2be8527aabe
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically identified as related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of \objupdate and the ProgID 'EQUaTIoN.3' strongly indicate an attempt to exploit this vulnerability for initial execution. The document body contains a lure related to an assignment, common in phishing or social engineering attacks, to trick the user into opening the document and potentially enabling editing, which would trigger the exploit.

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_off000059e3.bin
b6adc1ffe15a294859d15a8b9f99ec515775f2e76a6bfcd44736882fcac5e9c7		 rtf-objdata-decoded RTF \objdata at offset 0x59E3 1760 bytes

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