Malicious RTF — malware analysis report

Static analysis result for SHA-256 79574ed70893d2f9…

MALICIOUS

RTF

1.30 MB First seen: 2019-08-04
MD5: fff056fa3b28e91fcb219e1ded5fdc15 SHA-1: dd869985aaa2843cc7e1c1979d42d5f7336a6274 SHA-256: 79574ed70893d2f9f8e9886f3cc507f53cf9457a8f80751a298f02a4e2209dea
260 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an RTF document containing embedded OLE object data, specifically triggering heuristics related to Equation Editor vulnerabilities. ClamAV identifies this as Rtf.Exploit.CVE_2017_11882-6584355-1, indicating exploitation of the Equation Editor vulnerability. This technique is commonly used to deliver a second-stage payload, likely executed via the ".objupdate" directive.

Heuristics 6

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • Ole10Native stream in RTF OLE object high CVE related RTF_OLE10NATIVE_STREAM
    RTF contains an embedded OLE object with an Ole10Native stream. This is a strong payload-container signal and is related to Word/OLE exploit delivery, but it is not specific enough on its own to assign a CVE.
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • \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 ~1352KB 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_off0014a1c1.bin rtf-objdata-decoded RTF \objdata at offset 0x14A1C1 3621 bytes
SHA-256: 3dd64f074a3072dafe0bd5b6b7ec8da405fb7b1bad0f823547067fee20db71fe