Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 1fdf52bb6de99c79…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-15
MD5: 9ab9d7831fdf2c4e8399a1c23c1e4b0c SHA-1: d5cda4c8b08429e733cbdfcb71def0c510512a17 SHA-256: 1fdf52bb6de99c7987bdb46492ff375ff8601da7e57fe3ea230fae9623c76f23
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that leverages the Equation Editor vulnerability (CVE-2017-11882). The ".objupdate" directive forces the activation of this object, leading to arbitrary code execution. The decoded object data suggests the presence of embedded script, likely intended to download and execute a secondary payload.

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_off00001347.bin
659b7de347780174cda65714f0492b7edb5b34393ea908e91587b1f612bf0af4		 rtf-objdata-decoded RTF \objdata at offset 0x1347 25596 bytes
objdata_01_off0001954a.bin
689965aaaf88dfda2c46136e8ee45ccbdf5d380abcba88d5f9ff529d3c59ced2		 rtf-objdata-decoded RTF \objdata at offset 0x1954A 463381 bytes

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