Horizon Alert
Summary of the vulnerability and why it matters
A vulnerability has been identified in how certain encryption algorithms handle empty data, potentially allowing for the acceptance of forged messages if applications do not correctly verify security tags. This issue is in a foundational cryptography library, meaning its impact depends on how specific applications are built and used. The main concern at this stage is to confirm if any of our systems utilize this specific function in a way that could be exposed.
- Encryption could be tricked into accepting bad data.
- Concerns core security processing; confirm usage.
- Verify if specific application patterns are exposed.
Attack Path
How an attacker could exploit the issue
An attacker could trick an application into accepting forged messages by exploiting a flaw in how certain encryption algorithms handle empty data. This happens when an application uses a specific function and passes it empty data, and the application incorrectly assumes the message's integrity has been verified.
- No authentication needed.
- Empty ciphertext triggers flaw.
- Accepts forged messages.
Live Threat
Current exploitation, exposure, and threat context
When applications process empty ciphertexts using specific AEAD ciphers and finalize the operation with EVP_Cipher(), the integrity tag is not verified. This could lead to the acceptance of forged messages if the application relies on a successful return from EVP_Cipher() to indicate a valid tag.
- Authenticated message integrity.
- Empty ciphertext passed to EVP_Cipher().
- Acceptance of forged messages.
Operational Fix
Recommended remediation, mitigation, and detection steps
The identified vulnerability in cryptographic decryption routines impacts applications that process empty ciphertexts with specific AEAD ciphers and rely on the EVP_Cipher() function for tag verification. Application owners and platform teams are likely responsible for reviewing their code for this specific implementation pattern. The first practical step is to identify applications using these cryptographic functions, confirm their exposure and criticality, and then plan remediation, which may involve code updates or configuration changes.
- Identify accountable application owners.
- Verify applications using empty ciphertexts.
- Plan remediation based on exposure.
