Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a526cd067306a5dc…

MALICIOUS

RTF / .DOC

1.72 MB
MD5: 5c60acf507b71e1dbe92adec3f4b596a SHA-1: 08543cbe7f42174c9d9644ccf766fe66a9ee5c04 SHA-256: a526cd067306a5dc8d13e3ccf88509881425165a7fd0814e4b88deda8a19f3c3
260 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains multiple critical heuristic firings indicating the exploitation of CVE-2017-11882 through an embedded Equation Editor OLE object. The large amount of hex-encoded data within the OLE object suggests it is used to hide a malicious payload. The exploitation of this vulnerability typically leads to the execution of a second-stage payload.

Heuristics 6

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 ~1802KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000ad.bin
69c985bf1d99fac47c5dc411eee2f82c48ff93dbbc9f8907a021d74c5bd43611		 rtf-objdata-decoded RTF \objdata at offset 0xAD 901270 bytes

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