Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 558f07ceb8134e97…

MALICIOUS

RTF / .DOC

1.79 MB
MD5: a98227ecc9a7b47816587d52d7759e46 SHA-1: 3473ae74414fd62dba9c01f8bafe5c026467cad4 SHA-256: 558f07ceb8134e978b51fc18d4217556da7d6ae8c77d9f94c8f5579231f0054a
220 Risk Score

Malware Insights

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

The sample exhibits classic indicators of an Equation Editor exploit, specifically targeting CVE-2017-11882 or CVE-2018-0802. The presence of  objupdate to force automatic activation and a large, PE-like payload embedded within an Equation.3 OLE object strongly suggests an attempt to achieve remote code execution. No scripts were extracted from this sample, but the binary payload in the objdata section is the primary delivery mechanism.

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 ~1877KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003c.bin
35e467b4e6fb8609cfbff7968b16a36f0401f3c7eb3daeb62254c5acd4867b98		 rtf-objdata-decoded RTF \objdata at offset 0x3C 938729 bytes

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