ReliaQuest Reports Using Claude Mythos for Defensive Security Testing
Summary
ReliaQuest describes internal tests using Claude Mythos for attack-path analysis, adversary simulation, and control validation, reporting results from a synthetic infostealer chain and detection-library review. The findings are ReliaQuest’s claims, not independently验证ed
Key points
- ReliaQuest says it is testing Claude Mythos for defensive attack-surface analysis, adversary simulation, and security-control validation.
- In cloud testing, Mythos reportedly identified an obscure API function with hidden access implications; the article does not name the function.
- ReliaQuest says Mythos generated a weaponized proof of concept in one day during a PHP2Shell rebuild involving four bugs across two CVEs.
- On a synthetic 41-stage macOS infostealer chain, Mythos 5.1 reportedly achieved 39% first-guess accuracy for predicting the next activity.
- Mythos reviewed part of ReliaQuest’s detection library in 1.5 hours, compared with 4.5 hours for a baseline frontier model, and reportedly needed about 50% fewer interaction turns.
- ReliaQuest recommends validating controls against attack paths, auditing telemetry, mapping likely exposure points, and modernizing response processes.
Article Details
- Topic
- ReliaQuest's defensive testing of Anthropic's Claude Mythos for cybersecurity operations
Vendors
AnthropicClaude Mythos represents an important step forward in cybersecurity. Through our partnership with Anthropic, ReliaQuest is among the few to have access to Mythos, actively deploying its advanced reasoning capabilitiesReliaQuestMythos represents an important step forward in cybersecurity. Through our partnership with Anthropic, ReliaQuest is among the few to have access to Mythos, actively deploying its advanced reasoning capabilities for
Products
Claude Haiku 4.5likely next move. Mythos 5.1 achieved the top first-guess accuracy at 39%, followed by Opus 5.5 (34%), Haiku 4.5 (15%), and Sonnet 4.6 (12%).Claude MythosClaude Mythos represents an important step forward in cybersecurity. Through our partnership with Anthropic, ReliaQuest is among the few to have access to Mythos, actively deploying its advanced reasoning capabilitiesClaude Opus 5.5the attacker’s likely next move. Mythos 5.1 achieved the top first-guess accuracy at 39%, followed by Opus 5.5 (34%), Haiku 4.5 (15%), and Sonnet 4.6 (12%).Claude Sonnet 4.65.1 achieved the top first-guess accuracy at 39%, followed by Opus 5.5 (34%), Haiku 4.5 (15%), and Sonnet 4.6 (12%).Mythos 5.1In testing across a 41-stage synthetic macOS infostealer attack chain, Mythos 5.1 led the other models in predicting the attacker’s likely next move. Mythos 5.1 achieved the top first-guess accuracy at 39%, followed by