Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 4730874c95b68b14…

MALICIOUS

RTF / .DOC

1.71 MB
MD5: 240abfcfdc4f102cd6ff271076e932b0 SHA-1: eeef2cd6c2d659418a3458240b3ceebdf2157a7a SHA-256: 4730874c95b68b146dc126f4b4a0ee2e1da32366e3027ae8021e2f5b7a7cdc48
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: User Execution of Malicious Code T1566.001 Phishing: Spearphishing Attachment T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute a secondary payload. The presence of OLE object data and specific heuristics like RTF_EQUATION_EDITOR and CVE_2017_11882_RELATED strongly indicate this exploit. The large amount of hex-encoded data within the OLE object suggests it's hiding the actual malicious executable. No scripts were extracted, but the exploit mechanism is clear.

Heuristics 5

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact 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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1783KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001022.bin
f5672c74ce64e29d07bde8104805ca3b8ce0d93d820db7b1cd7fb922fa716e2f		 rtf-objdata-decoded RTF \objdata at offset 0x1022 891702 bytes

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