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Claude Fable 5.1 Solves the Cyphral Distich, a 370-year-old cipher
Claude Fable 5.1 solved Sir Thomas Urquhart's 370-year-old Cyphral Distich cipher, recovering a hidden royalist prayer for Charles II.
Vals AI reports that Claude Fable 5.1 solved the Cyphral Distich, a 64-number cryptogram from Sir Thomas Urquhart's Logopandecteision unsolved since 1653, in 44 minutes using 176k tokens with no human hints. The key insight was that the cipher's key was the book itself: each number indexes a word in the corresponding Proquiritation, taking the first letter, yielding 'O GOD UPHOLD KING CHARLS THE SECOND AND MAKE HIM THE SUPREME RULER OF THIS LAND'. The model also deciphered the larger Cyphral Octastich (285 numbers) from The Jewel (1652) using page-based word indexing, recovering all but nine letters of a royalist prayer. The puzzle had been listed among Klaus Schmeh's Top 50 unsolved encrypted messages.
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MILE TEA: Cyber Espionage Campaign Targets Asia Pacific Businesses and Government Agencies
Unit 42 names MILE TEA, a cyber-espionage campaign since 2011 targeting Japanese and Taiwanese businesses and government agencies with e-ticket phishing lures and Elirks-family malware.
Unit 42 tracks the MILE TEA espionage campaign, observed as early as 2011, targeting Japanese trading, petroleum, and mobile companies, a Beijing office of a Japanese public organization, and a Taiwanese government agency. The primary infection vector is spear-phishing emails with attachments, mostly custom executable installers posing as flight e-tickets, dropping Elirks, Micrass, or Logedrut as initial bridgehead malware. Elirks and Logedrut retrieve encrypted C2 addresses from attacker-posted blog articles, decoded with Base64 and TEA or DES ciphers. The campaign's focus shifted from Taiwan to Japan around 2013.
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DPRK APTs: Ted backdoor and curlRAT target South Korean media and automotive sectors
Rapid7 uncovered a DPRK-linked Linux toolkit using a HAProxy-embedded ted backdoor, SSH keylogger, and curlRAT against South Korean media and automotive firms.
Rapid7 Labs identified a previously undocumented framework attributed with medium confidence to DPRK actors, targeting South Korean automotive and media organizations likely since early 2025. The toolkit embeds a backdoor compiled into HAProxy 2.8.12 using its filter API, plus trojanized crond, agetty, atd, sshd, and polkitd, an SSH keylogger storing credentials under /var/lib/sshd/, and a curl-based RAT with a watchdog thread. It enables remote command execution, malicious script injection into served webpages (a watering-hole loop), credential harvesting, and long-term surveillance. Hardcoded C2s are associated with APT37 via ThreatFox, and exposed groupware portals and mail servers align with Kimsuky tradecraft; the initial access vector and any CVE remain unconfirmed.
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“Tick” Group Continues Attacks
Unit 42 tracks the Tick espionage group attacking Korean and Japanese defense and high-tech targets with Daserf, Minzen, 9002, Invader, and custom Gh0st RAT variants.
The Tick group has conducted long-running espionage attacks against organizations in the Republic of Korea and Japan, focusing on defense and high-tech companies holding intellectual property, and repeatedly attacked one high-profile Japanese target for three years. Unit 42 links the Daserf backdoor, the 9002 RAT, and the Invader backdoor through shared C2 infrastructure used between July 2012 and April 2013. Minzen samples install a "NamelessHdoor" backdoor derived from publicly available code over a decade old, modified with ReflectiveDLLLoader DLL injection, and the group also uses custom Gh0st RAT variants. Tick has shifted from privacy-protected domain registration to compromised websites for C2 infrastructure.
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Bisonal Malware Used in Attacks Against Russia and South Korea
Unit 42 details a Bisonal malware variant, active since 2014, targeting Russian and South Korean defense organizations via PDF-disguised spearphishing emails.
In early May, Unit 42 discovered a campaign delivering a Bisonal malware variant against at least one Russian communications security and cryptography company and one unidentified organization in South Korea. The variant, in the wild since at least 2014, introduces a new C2 cipher and rewritten networking and persistence code, with only 14 samples collected to date. Attackers spoofed Russian state corporation Rostec in spearphishing emails carrying an executable disguised with a PDF icon; the dropper decrypts an RC4-encrypted DLL and establishes persistence via a registry Run key. Bisonal has been used since 2013 against government, military, and defense targets in South Korea, Russia, Japan, and India, alongside successors Bioazih and Dexbia.
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Claude Fable Solves a Historical Cipher
Bruce Schneier's blog highlights that the Claude Fable AI model solved a historical cipher, demonstrating LLM capabilities in cryptanalysis.
Bruce Schneier's blog post discusses the Claude Fable AI model successfully deciphering a historical cipher. The post frames the result as a notable example of LLMs applied to classical cryptanalysis. The published text provides limited technical detail beyond the headline.
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