Malicious RTF — malware analysis report

Static analysis result for SHA-256 eb171136fc627886…

MALICIOUS

RTF

1.78 MB
MD5: 72c0ad8a90304582b82feb6482c84836 SHA-1: 00efcb9bef85ebf69a48d81c46c659b431905e92 SHA-256: eb171136fc6278864dd32189da39106fe93b9ce615e3a72311c2a32c583e1738
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment T1204.002 User Execution: Malicious File

The sample is an RTF document containing embedded OLE objects and the Equation.3 ProgID, which is specifically designed to trigger CVE-2017-11882 or CVE-2018-0802. The use of  objupdate forces automatic activation of the object upon opening, a hallmark of these exploits. No scripts were extracted from this sample, so the second-stage payload delivery mechanism is not visible.

Heuristics 5

  • 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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000011e1.bin
c6b312ddd97d86430d076a0206f8d4d3cfe272750fded36b4162ea1fddedfd2a		 rtf-objdata-decoded RTF \objdata at offset 0x11E1 53976 bytes
objdata_01_off0002fde3.bin
abd132bf3ab8190dfb030bcb879a36061e9aef78c1060b63bd0588b35c7d316c		 rtf-objdata-decoded RTF \objdata at offset 0x2FDE3 454791 bytes

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