CAPEC-68: Subvert Code-signing Facilities
CAPEC版本: 3.9
更新日期: 2023-01-24
攻击模式描述
Many languages use code signing facilities to vouch for code's identity and to thus tie code to its assigned privileges within an environment. Subverting this mechanism can be instrumental in an attacker escalating privilege. Any means of subverting the way that a virtual machine enforces code signing classifies for this style of attack.
前提条件
- A framework-based language that supports code signing (such as, and most commonly, Java or .NET)
- Deployed code that has been signed by its authoring vendor, or a partner.
- The attacker will, for most circumstances, also need to be able to place code in the victim container. This does not necessarily mean that they will have to subvert host-level security, except when explicitly indicated.
所需技能
所需资源
- The Attacker needs no special resources beyond the listed prerequisites in order to conduct this style of attack.
后果影响
影响范围: Confidentiality Access Control Authorization
技术影响: Gain Privileges
缓解措施
A given code signing scheme may be fallible due to improper use of cryptography. Developers must never roll out their own cryptography, nor should existing primitives be modified or ignored.
If an attacker cannot attack the scheme directly, they might try to alter the environment that affects the signing and verification processes. A possible mitigation is to avoid reliance on flags or environment variables that are user-controllable.
示例实例
In old versions (prior to 3.0b4) of the Netscape web browser Attackers able to foist a malicious Applet into a client's browser could execute the "Magic Coat" attack. In this attack, the offending Applet would implement its own getSigners() method. This implementation would use the containing VM's APIs to acquire other Applet's signatures (by calling _their_ getSigners() method) and if any running Applet had privileged-enough signature, the malicious Applet would have inherited that privilege just be (metaphorically) donning the others' coats.
Some (older) web browsers allowed scripting languages, such as JavaScript, to call signed Java code. In these circumstances, the browser's VM implementation would choose not to conduct stack inspection across language boundaries (from called signed Java to calling JavaScript) and would short-circuit "true" at the language boundary. Doing so meant that the VM would allow any (unprivileged) script to call privileged functions within signed code with impunity, causing them to fall prey to luring attacks.
The ability to load unsigned code into the kernel of earlier versions of Vista and bypass integrity checking is an example of such subversion. In the proof-of-concept, it is possible to bypass the signature-checking mechanism Vista uses to load device drivers.
分类映射
| 分类名称 | 条目ID | 条目名称 |
|---|---|---|
| ATTACK | 1553.002 | Subvert Trust Controls: Code Signing |