Adversaries may attempt to mimic features of valid code signatures to increase the chance of deceiving a user, analyst, or tool. Code signing provides a level of authenticity on a binary from the developer and a guarantee that the binary has not been tampered with. Adversaries can copy the metadata and signature information from a signed program, then use it as a template for an unsigned program. Files with invalid code signatures will fail digital signature validation checks, but they may appear more legitimate to users and security tools may improperly handle these files.[1]
Unlike Code Signing, this activity will not result in a valid signature.
| ID | Name | Description |
|---|---|---|
| G0067 | APT37 |
APT37 has signed its malware with an invalid digital certificates listed as "Tencent Technology (Shenzhen) Company Limited."[2] |
| S0128 | BADNEWS |
BADNEWS is sometimes signed with an invalid Authenticode certificate in an apparent effort to make it look more legitimate.[3] |
| S0666 | Gelsemium |
Gelsemium has used unverified signatures on malicious DLLs.[4] |
| S0198 | NETWIRE |
The NETWIRE client has been signed by fake and invalid digital certificates.[5] |
| S1050 | PcShare |
PcShare has used an invalid certificate in attempt to appear legitimate.[6] |
| S0019 | Regin |
Regin stage 1 modules for 64-bit systems have been found to be signed with fake certificates masquerading as originating from Microsoft Corporation and Broadcom Corporation.[7] |
| G0112 | Windshift |
Windshift has used revoked certificates to sign malware.[8][9] |
| S0466 | WindTail |
WindTail has been incompletely signed with revoked certificates.[8] |
| ID | Mitigation | Description |
|---|---|---|
| M1045 | Code Signing |
Require signed binaries. |
| ID | Data Source | Data Component | Detects |
|---|---|---|---|
| DS0022 | File | File Metadata |
Collect and analyze signing certificate metadata and check signature validity on software that executes within the environment, look for invalid signatures as well as unusual certificate characteristics and outliers. |