Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8186b7bd2ed72735…

MALICIOUS

RTF / .DOC

1.96 MB
MD5: 61ce58b77fd0b03307906d3a0764a98f SHA-1: 22951371311999793762b0ba721ccbfa329fd413 SHA-256: 8186b7bd2ed72735965e9be4d374546c7597d4f43f38234f74119d4eb0ad4c28
180 Risk Score

Malware Insights

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

The RTF document contains multiple indicators of exploitation for CVE-2017-11882, specifically related to the Equation Editor. The presence of OLE objects and the ".objupdate" directive strongly suggest that the embedded Equation Editor object is being activated to execute arbitrary code. The decoded object data contains obfuscated VBScript that appears to be designed to download and execute a second-stage payload, although the full script could not be reconstructed.

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
4d163f11cbb699ebd573b0f9fa6d30dd6419cea34d09765e5f4044c4c17cf44c		 rtf-objdata-decoded RTF \objdata at offset 0x1116 25620 bytes
objdata_01_off00019205.bin
ac9bfb081d4e3f91c1d530b09d33124ea631b81e03f3efc0b3eee9f29b094bb3		 rtf-objdata-decoded RTF \objdata at offset 0x19205 463381 bytes

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