Malicious RTF — malware analysis report

Static analysis result for SHA-256 4cbdd332e3cc18da…

MALICIOUS

RTF

1.63 MB
MD5: 9d832fcecfcdace769f7215d03874511 SHA-1: 1dcc051c95304e0a998eb13de309f67245f6fe7d SHA-256: 4cbdd332e3cc18da5b80dffb8068d4f6bced41852cfa54b956c03b024a7e5e62
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter

The sample is an RTF document containing an Equation.3 object and the \objupdate control word, which is a strong indicator of CVE-2017-11882 or CVE-2018-0802 exploitation. No scripts were extracted from this sample, but the structural evidence and heuristic firings strongly suggest an attempt to trigger a buffer overflow in the Equation Editor component to execute arbitrary code.

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
afb68329ef7ac016b76b855a29cffbfc739cc96305f1a9fc897f112a3f606ae1		 rtf-objdata-decoded RTF \objdata at offset 0x11E1 53954 bytes
objdata_01_off0002faeb.bin
0a0103f81ecaf6eb904befe7f328952354a33a6d49f64b01ead02ee216cb69c4		 rtf-objdata-decoded RTF \objdata at offset 0x2FAEB 410074 bytes

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