Insecure Direct Object Reference in OpenSign Contact Retrieval

An insecure direct object reference vulnerability in OpenSignLabs OpenSign through 2.37.0 allows unauthenticated remote attackers to retrieve any contact record via the getcontact Parse cloud function. The function executes with useMasterKey and performs no authentication or authorization checks before returning the requested contact object. An attacker can enumerate and read all contact records including personally identifiable information without credentials.

Casky was already ahead

This CVE exploits attack patterns that Casky's 283matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

CVE-2026-72543 exploits an insecure direct object reference (IDOR) vulnerability in OpenSign's getcontact Parse cloud function, allowing unauthenticated attackers to retrieve arbitrary contact records. The function executes with master key privileges but performs no authentication or authorization validation before returning sensitive contact data, including personally identifiable information. Any OpenSign installation through version 2.37.0 is affected, making this a critical risk for organizations using this platform to manage contact information. The vulnerability requires no credentials, making it trivially exploitable for reconnaissance and data harvesting attacks.

Casky's 283 mapped skills detect the attack patterns underlying this vulnerability by correlating MITRE ATT&CK techniques TA0004 (Privilege Escalation) and TA0006 (Credential Access). Practitioners using Casky would identify suspicious patterns including: unauthenticated API requests to the getcontact function (Privilege Escalation via abuse of elevated function permissions), sequential enumeration of contact IDs indicating data exfiltration attempts (Credential Access via IDOR), and anomalous access patterns from external sources accessing cloud functions without valid session tokens. Claude's extended reasoning capabilities help practitioners understand not just that requests are occurring, but the logical chain—how missing authorization checks combined with master key execution create a direct path to unauthorized data access—enabling faster threat detection and remediation across their security posture.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

283 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-72543.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

cryptography · low

Run

MITRE ATT&CK Techniques

TA0004 TA0006

Investigate the attack patterns behind CVE-2026-72543

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