Incident Score: Analysis & Impact (ANT1779337466)
The details regarding individual company incidents & reports gives you full view from every side.
Rankiteo Score Impact Analysis
Key Highlights From The Incident Analysis
- Timeline of Anthropic's Vulnerability and lateral movement inside company's environment.
- Overview of affected data sets, including SSNs and PHI, and why they materially increase incident severity.
- How Rankiteo’s incident engine converts technical details into a normalized incident score.
- How this cyber incident impacts Anthropic Rankiteo cyber scoring and cyber rating.
- Rankiteo’s MITRE ATT&CK correlation analysis for this incident, with associated confidence level.
Full Incident Analysis Transcript
In this Rankiteo incident briefing, we review the Anthropic breach identified under incident ID ANT1779337466.
The analysis begins with a detailed overview of Anthropic's information like the linkedin page: https://www.linkedin.com/company/anthropicresearch, the number of followers: 1898947, the industry type: Research Services and the number of employees: 3717 employees
After the initial compromise, the video explains how Rankiteo's incident engine converts technical details into a normalized incident score. The incident score before the incident was 625 and after the incident was 621 with a difference of -4 which is could be a good indicator of the severity and impact of the incident.
In the next step of the video, we will analyze in more details the incident and the impact it had on Anthropic and their customers.
On 01 April 2026, Anthropic disclosed Sandbox Bypass issues under the banner "Anthropic’s Claude Code AI Assistant Plagued by Critical Sandbox Bypass for Over Five Months".
Anthropic’s Claude Code AI coding assistant contained a severe network sandbox bypass vulnerability for more than five months, enabling attackers to exfiltrate sensitive data including credentials, source code, and environment variables from developer systems.
The disruption is felt across the environment, affecting Developer systems running Claude Code v2.0.24 to v2.1.89, and exposing Credentials (AWS, GitHub tokens), source code, environment variables, internal API endpoints, corporate intranet resources, model API keys.
In response, moved swiftly to contain the threat with measures like Silent patch in v2.1.90 (April 1, 2026), and began remediation that includes Added isValidHost() wrapper in sandbox-runtime 0.0.43 to block malicious characters (\x00, %, CRLF), while recovery efforts such as Users advised to update to v2.1.90 or later and rotate exposed credentials continue, and stakeholders are being briefed through No security advisory issued; patch not acknowledged in release notes.
The case underscores how Resolved (silently patched), teams are taking away lessons such as Systemic implementation flaws in sandboxing can lead to prolonged exposure; input sanitization is critical for security controls; silent patching undermines trust and transparency, and recommending next steps like Update to Claude Code v2.1.90 or later, Rotate all exposed credentials (AWS, GitHub, etc.) and Audit outbound SOCKS-mediated traffic logs for suspicious activity, with advisories going out to stakeholders covering Users advised to update and rotate credentials; no official advisory issued by Anthropic.
Finally, we try to match the incident with the MITRE ATT&CK framework to see if there is any correlation between the incident and the MITRE ATT&CK framework.
The MITRE ATT&CK framework is a knowledge base of techniques and sub-techniques that are used to describe the tactics and procedures of cyber adversaries. It is a powerful tool for understanding the threat landscape and for developing effective defense strategies.
MITRE ATT&CK® Correlation Analysis
Rankiteo's analysis has identified several MITRE ATT&CK tactics and techniques associated with this incident, each with varying levels of confidence based on available evidence. Under the Initial Access tactic, the analysis identified Exploit Public-Facing Application (T1190) with moderate confidence (60%), supported by evidence indicating claude Code AI coding assistant contained a severe network sandbox bypass vulnerability and Exploitation for Client Execution (T1203) with moderate to high confidence (70%), supported by evidence indicating sOCKS5 hostname null-byte injection exploited via parser differential. Under the Execution tactic, the analysis identified Command and Scripting Interpreter (T1059) with moderate confidence (50%), supported by evidence indicating malicious instructions embedded in GitHub issues, READMEs, or documentation. Under the Credential Access tactic, the analysis identified Steal Application Access Token (T1528) with high confidence (90%), supported by evidence indicating aWS credentials (~/.aws/), GitHub tokens (~/.config/gh/) exfiltrated and Cloud Instance Metadata API (T1552.005) with moderate to high confidence (80%), supported by evidence indicating cloud instance metadata (169.254.169.254) exfiltrated. Under the Collection tactic, the analysis identified Data from Local System (T1005) with high confidence (90%), supported by evidence indicating source code, environment variables, internal API endpoints compromised and Data from Information Repositories (T1213) with moderate to high confidence (70%), supported by evidence indicating corporate intranet resources and model API keys exfiltrated. Under the Exfiltration tactic, the analysis identified Exfiltration Over C2 Channel (T1041) with high confidence (90%), supported by evidence indicating data exfiltrated via attacker-controlled domains (attacker-host.com) and Transfer Data to Cloud Account (T1537) with moderate confidence (60%), supported by evidence indicating aWS credentials and cloud metadata exfiltrated to attacker domains. Under the Defense Evasion tactic, the analysis identified Obfuscated Files or Information (T1027) with moderate to high confidence (80%), supported by evidence indicating sOCKS5 hostname null-byte injection (\x00.google.com) bypassed allowlist and Disable or Modify Tools (T1562.001) with moderate confidence (50%), supported by evidence indicating silent patching without acknowledging security fix in release notes. Under the Impact tactic, the analysis identified Defacement: Internal Defacement (T1491.001) with lower confidence (40%), supported by evidence indicating potential unauthorized access to corporate intranet resources. These correlations help security teams understand the attack chain and develop appropriate defensive measures based on the observed tactics and techniques.
Sources & References
- Anthropic Rankiteo Cyber Incident Details: https://www.rankiteo.com/company/anthropicresearch/incident/ANT1779337466
- Anthropic CyberSecurity Rating page: https://www.rankiteo.com/company/anthropicresearch
- Anthropic Rankiteo Cyber Incident Blog Article: https://blog.rankiteo.com/ant1779337466-anthropic-vulnerability-october-2025/
- Anthropic CyberSecurity Score History: https://www.rankiteo.com/company/anthropicresearch/history
- Anthropic CyberSecurity Incident Source: https://cybersecuritynews.com/claude-codes-network-sandbox-vulnerability/
- Rankiteo A.I CyberSecurity Rating methodology: https://www.rankiteo.com/Images/rankiteo_algo.pdf
- Rankiteo TPRM Scoring methodology: https://static.rankiteo.com/model/rankiteo_tprm_methodology.pdf