Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 59feeae1427f7112…

MALICIOUS

RTF / .DOC

1.96 MB
MD5: 99aabdb7248de4a8573887d8763b561e SHA-1: 48494e9d0200ac8a69a8f806a6030b661518b6bb SHA-256: 59feeae1427f71126ee2a3db6eeac8fe02946467994674f674e0912e29cf7ea1
180 Risk Score

Malware Insights

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

The critical heuristic 'RTF_EQUATION_EDITOR' and high heuristic 'CVE_2017_11882_ACTIVATION_RELATED' indicate the exploitation of CVE-2017-11882. The presence of OLE object data and the ".objupdate" directive further support that an embedded object is being activated to execute code. The decoded object contains VBA-like script fragments that appear to be attempting to download and execute a second-stage payload, though the script is heavily obfuscated and truncated.

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_off00001116.bin
1d6ed0594f4b99912f313d2d2f7008351a37d93f32fb653b32b614dee2749958		 rtf-objdata-decoded RTF \objdata at offset 0x1116 25644 bytes
objdata_01_off00019235.bin
ac9bfb081d4e3f91c1d530b09d33124ea631b81e03f3efc0b3eee9f29b094bb3		 rtf-objdata-decoded RTF \objdata at offset 0x19235 463381 bytes

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