A vulnerability, which was classified as critical, has been found in Google Go 2019-03-25 (Programming Language Software). Affected by this issue is an unknown code block of the file crypto/openpgp/clearsign/clearsign.go of the component Crypto Library. The manipulation with an unknown input leads to a cryptographic issues vulnerability. Using CWE to declare the problem leads to CWE-310. Impacted is confidentiality, integrity, and availability. CVE summarizes:

A message-forgery issue was discovered in crypto/openpgp/clearsign/clearsign.go in supplementary Go cryptography libraries 2019-03-25. According to the OpenPGP Message Format specification in RFC 4880 chapter 7, a cleartext signed message can contain one or more optional "Hash" Armor Headers. The "Hash" Armor Header specifies the message digest algorithm(s) used for the signature. However, the Go clearsign package ignores the value of this header, which allows an attacker to spoof it. Consequently, an attacker can lead a victim to believe the signature was generated using a different message digest algorithm than what was actually used. Moreover, since the library skips Armor Header parsing in general, an attacker can not only embed arbitrary Armor Headers, but also prepend arbitrary text to cleartext messages without invalidating the signatures.

The bug was discovered 05/13/2019. The weakness was presented 05/22/2019 (Website). The advisory is shared for download at lists.debian.org. This vulnerability is handled as CVE-2019-11841 since 05/09/2019. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/23/2023). The MITRE ATT&CK project declares the attack technique as T1600.

The vulnerability was handled as a non-public zero-day exploit for at least 9 days. During that time the estimated underground price was around $5k-$25k.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Type

• Programming Language Software

Vendor

• Google

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• Go

Version

• 2019-03-25

License

• open-source

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