Secure Boot, TPM and Anti-Cheat Engines

With cheating becoming more and more prevalent in online multiplayer games, some anti-cheat vendors have decided to start leveraging hardware and firmware security features. Electronic Arts recently announced that their newest title, Battlefield 6, would require players to have both Secure Boot and their firmware TPM (supporting the TPM 2.0 spec) enabled in order to be able to play the game. Riot’s Vanguard [has similar requirements for players on Windows 11], and it is suspected that with the upcoming end of Windows 10’s support, Riot will extend that requirement to all players. Secure Boot and TPM 2.0 have been soft requirements to install Windows 11 for some time, so with Windows 10’s end-of-life, it seems like a good time for anti-cheat vendors to require those security features.

This sudden change, however, has caused a little uproar in some gaming communities, with some vocal dissenters trying to frame this as nothing more than a ruse to force players on a specific operating system, to prevent them from playing on older hardware, or as a massive overreach that has the sole goal of pilfering players’ data in order to sell it.

In order to understand why anti-cheat vendors are now relying on those security features, we must first understand how they work (in this specific context), what are the privacy implications, and why they could be effective at significantly reducing one specific kind of cheating.

Important

It is important to note that the primary goal of anti-cheat engines is not to prevent cheating before it happens. The goal of anti-cheat engines is to put technological barriers in place to make it harder for cheat developers; to make detection of cheating packages easier; and to ensure that, when detected, banned cheaters are not able to evade their ban.

There will always be cheating in any type of game, computerised or not, online or not. However, with proper measures, anti-cheat providers can ensure that the incentive to cheat is greatly reduced. This naturally leads to a decrease in the number of cheaters, and a better experience for regular players.

Secure Boot

Secure Boot is simply a mechanism for your motherboard’s firmware to verify that the UEFI image it is executing during the boot sequence (which could be an OS bootloader, an option ROM, or any other EFI application) hasn’t been modified by a malicious actor.

To do so, Secure Boot relies on a hierarchy of keys to establish who is authorised to update the database of authorised signatures, which are used to ultimately validate the boot image.

At the top of the hierarchy lies the Platform Key (PK). On the x86-64 platform, this is normally the public key of your motherboard vendor by default. For example, if you have a GIGABYTE motherboard, you may find that your motherboard shipped with this PK configured by default.

Version:          3 (0x02)
Serial number:    252254444493706055650493858147631885892 (0xbdc67056de877e8247ac699c054fee44)
Algorithm ID:     SHA256withRSA
Validity
  Not Before:     05/09/2023 06:37:57 (dd-mm-yyyy hh:mm:ss) (230905063757Z)
  Not After:      05/09/2053 06:37:56 (dd-mm-yyyy hh:mm:ss) (20530905063756Z)
Issuer
  CN = GIGABYTE
Subject
  CN = GIGABYTE
Fingerprints
  MD5:            8b42dd84de1b6d5598f8324227db7d7c
  SHA1:           fcfc537049ff5260ef60b640c18d994236d60280
  SHA256:         f260331de605555f2f075028e1adbfffb52cac3a12c5f65f67ab044997f6afc8

While your motherboard’s manufacturer will ship with their PK by default, note that you can usually replace it with your own public key if you want. This requires you to put Secure Boot in Setup Mode, and the procedure to do so will change depending on your motherboard¹. The PK exists to establish a trust relationship between the firmware, and the platform owner. That’s normally you for your own computer.

The Platform Key (PK) indicates who is authorised to make changes to the next type of key in the key hierarchy: Key Echange Keys (KEK).

Key Exchange Keys (KEK) determine who is authorised to make changes to the various signature databases. They exist to establish a trust relationship between the operating system, and the firmware. By default, your motherboard should ship with Microsoft’s KEKs, and in some cases a motherboard manufacturer KEK. Any update to the KEKs must be signed by the private key (PKpriv) that corresponds to the Platform Key (PK). This prevents unauthorised users or software from modifying the KEK variable.

This, however, means that any change to the KEKs must be done in coordination with the hardware manufacturers. Microsoft is in the process of introducing a new KEK due to the upcoming expiry of their old one, and they therefore have to coordinate with the various vendors in order to get their update signed. Fortunately, KEKs are rarely updated.

Finally, we have the authorised signatures database (DB) and the forbidden signatures database (DBX). In the case of Microsoft Windows, the databases are signed directly by Microsoft’s KEK, and distributed via Windows Update.

To recap the key hierarchy, from the top level to the bottom level:

Name	varname	Description
Platform Key	PK	Establishes a trust relationship between the platform owner and the platform firmware. Used to enroll a Key Exchange Key.
Key Exchange Key	KEK	Establishes a trust relationship between the operating system and the platform firmware.
Authorised signatures database	DB	Database of public certificates and signatures that are used to authenticate UEFI images that will be booted.
Forbidden signatures database	DBX	Database of public certificates and signatures that are used to authenticate UEFI images that will be booted. If an image validates against a forbidden signature, it is prevented from booting.

Before your UEFI firmware executes an UEFI image (which could be an OS bootloader, an option ROM, or any other EFI application), it validates it against the signatures in the database (DB). If the image isn’t signed, the signature matches against an entry in the forbidden signatures database (DBX), or the signature can’t be validated against the authorised signatures database (DB), then the boot process is aborted.

Windows’ bootloader also uses the database to validate the signature of any kernel-level drivers it loads. However, it will only consider signatures that were signed by Microsoft’s keys². If the kernel-level driver isn’t signed by Microsoft, or its signature is found in the forbidden signatures database (DBX), it will not load that driver.

Microsoft adds signatures into the forbidden signatures database (DBX) when it detects a driver with a vulnerability that allows malicious actors to execute unsigned code within kernel space. This effectively prevents vulnerable versions of those drivers from loading.

Since cheat authors will not be able to get their drivers signed by Microsoft, forcing players to have Secure Boot on is an effective way of preventing cheats from being able to install themselves into kernel space without having to resort to some unknown or unpatched exploit.

That said, anti-cheat engines cannot trust that Secure Boot is indeed on even if the OS reports that it is. A cheater or malicious actor could, with it off, load a kernel-level driver that would make the OS believe that it is on. This is where the TPM comes in.

Trusted Platform Module

In the context of anti-cheat, the Trusted Platform Module (TPM) serves two main purposes:

Provide a unique identifier tied to the hardware that cannot be spoofed or modified by a malicious user or a cheater.
Get verifiable proof of the state of the boot environment to ensure that Secure Boot and the rest of the boot process wasn’t tampered with.

Banning the cheater’s hardware

Having a unique identifier for hardware allows anti-cheat providers to effectively ban a cheater once caught. This is particularly important, as cheaters, if caught and only account banned, could easily purchase or acquire another copy of the game on a different account (or simply create a new account in the case of a free-to-play game) and resume cheating. IP bans are not effective, as no ISPs grant, by default, a static IP address to their customers, and due to the exhaustion of the IPv4 address space, a lot of ISPs are now deploying CGNAT, which means that multiple subscribers are sharing the same IP.

Banning the cheater’s hardware is the only effective way to prevent the cheater from simply creating a new account. They would have to acquire new hardware in order to play the game they’ve been banned from again, and that gets expensive fast. The use of a TPM enables anti-cheat providers to uniquely identify the cheater’s hardware in a verifiable way.

For the purpose of hardware identification, it is important to note that there are multiple kinds of TPMs. Discrete TPMs (dTPM) are small TPM modules that you can purchase and install that are separate from your CPU and motherboard. These do not provide the same guarantees in terms of identifying the hardware, and I fully suspect that some anti-cheat providers will simply prevent access to the game if you use one of those.

AMD and Intel have, since about 2017, provided a firmware TPM (fTPM) as part of their CPU package on most of their processors. Since 2021, all their desktop and mobile offerings include a fTPM.

Each TPM is manufactured with a unique Endorsement Key (EK) that cannot be changed. The private portion of that key (EKpriv) cannot be extracted from the TPM, while the public portion (EKpub) can be read by software. fTPMs specifically also have a EKcert. The EKcert is a certificate that provides a guarantee that the EKpub does indeed come from a genuine fTPM manufactured by them. A malicious user, or cheater, would not be able to generate a fake EKpub, as it wouldn’t be validated by a EKcert from AMD or Intel.

By leveraging the EKpub, and validating it against the EKcert, anti-cheat providers are able to have a guarantee that the EKpub is indeed tied to genuine hardware. Since fTPMs are part of the CPU package, banning that particular EKpub would mean that the cheater would effectively have to purchase another CPU in order to keep cheating.

On Windows, you can retrieve your EKpub and EKcert in PowerShell by executing the following cmdlet:

Get-TpmEndorsementKeyInfo -HashAlgorithm SHA256

On Linux, given you have tpm2-tools³ installed, you can retrieve your EKpub and EKcert by executing the following commands:

# See TCG TPM v2.0 Provisioning Guidance for reserved handles.
# EK is at 0x81010001
# EKcert can be at 0x01C00002 or online depending on the vendor
sudo tpm2_readpublic -c 0x81010001 -o EKpub_TPM2B_PUBLIC.bin

# To have the public key in PEM format
sudo tpm2_readpublic -c 0x81010001 --format=pem -o EKpub_pem.pub

# Fetching the EKcert
sudo tpm2_getekcertificate -u EKpub_TPM2B_PUBLIC.bin -o EKcert_DER.cer

Measured Boot

Another important security component of the Trusted Platform Module that is leveraged by anti-cheat engines are the Platform Configuration Registers (PCR). Each of the 24 PCR contains SHA1 or SHA256 cryptographic hash based measurements of events. These events can occur during boot, or during runtime. For the purpose of anti-cheat validation, we are mostly interested in boot time events.

When an event is recorded via the command TPM2_PCR_Extend, the event’s data⁴ is concatenated with the previous hash registered in that PCR, and then hashed. This ensures that each PCR value can be used as cryptographic evidence of the integrity of all events extended to that PCR. If the log is replayed and the calculated PCR value doesn’t match the recorded PCR value, you know the log has been tampered with.

Each PCR bank is reserved for a specific purpose. For example, PCR 7 contains information about the SecureBoot state:

# Partial Windows Measured Boot log (PCR7 only + PCR value)
# Converted from binary format using
# tpm2-tools' tpm2_eventlog
---
version: 2
events:
  - EventNum: 3
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_DRIVER_CONFIG
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: 'ccfc4bb32888a345bc8aeadaba552b627d99348c767681ab3141f5b01e40a40e'
    EventSize: 53
    Event:
      VariableName: 8be4df61-93ca-11d2-aa0d-00e098032b8c
      UnicodeNameLength: 10
      VariableDataLength: 1
      UnicodeName: SecureBoot
      VariableData:
        Enabled: 'Yes'
  - EventNum: 4
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_DRIVER_CONFIG
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: 'f7605d30894abc33e05fe3b787c340a701bd25b3171337378c554f2b0d456745'
    EventSize: 846
    Event:
      VariableName: 8be4df61-93ca-11d2-aa0d-00e098032b8c
      UnicodeNameLength: 2
      VariableDataLength: 810
      UnicodeName: PK
      VariableData:
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 810
          SignatureHeaderSize: 0
          SignatureSize: 782
          Keys:
            - SignatureOwner: e58e05e2-5c43-4ef7-880b-3f06734eb36f
              SignatureData: 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
  - EventNum: 5
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_DRIVER_CONFIG
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: '4ff9961291a19b5d29cfad68f0b0e66790c25f3f6af2fd3bdd5b5901227b0d91'
    EventSize: 3922
    Event:
      VariableName: 8be4df61-93ca-11d2-aa0d-00e098032b8c
      UnicodeNameLength: 3
      VariableDataLength: 3884
      UnicodeName: KEK
      VariableData:
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1506
          SignatureHeaderSize: 0
          SignatureSize: 1478
          Keys:
            - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
              SignatureData: 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
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1560
          SignatureHeaderSize: 0
          SignatureSize: 1532
          Keys:
            - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
              SignatureData: 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
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 818
          SignatureHeaderSize: 0
          SignatureSize: 790
          Keys:
            - SignatureOwner: e58e05e2-5c43-4ef7-880b-3f06734eb36f
              SignatureData: 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
  - EventNum: 6
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_DRIVER_CONFIG
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: '02adb325bebf3d5891b691d461fd8d369b11a85a88db3d779cc0757dfcdb5640'
    EventSize: 6824
    Event:
      VariableName: d719b2cb-3d3a-4596-a3bc-dad00e67656f
      UnicodeNameLength: 2
      VariableDataLength: 6788
      UnicodeName: db
      VariableData:
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1600
          SignatureHeaderSize: 0
          SignatureSize: 1572
          Keys:
            - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
              SignatureData: 30820610308203f8a003020102020a6108d3c4000000000004300d06092a864886f70d01010b0500308191310b3009060355040613025553311330110603550408130a57617368696e67746f6e3110300e060355040713075265646d6f6e64311e301c060355040a13154d6963726f736f667420436f72706f726174696f6e313b3039060355040313324d6963726f736f667420436f72706f726174696f6e205468697264205061727479204d61726b6574706c61636520526f6f74301e170d3131303632373231323234355a170d3236303632373231333234355a308181310b3009060355040613025553311330110603550408130a57617368696e67746f6e3110300e060355040713075265646d6f6e64311e301c060355040a13154d6963726f736f667420436f72706f726174696f6e312b3029060355040313224d6963726f736f667420436f72706f726174696f6e2055454649204341203230313130820122300d06092a864886f70d01010105000382010f003082010a0282010100a5086c4cc745096a4b0ca4c0877f06750c43015464e0167f07ed927d0bb273bf0c0ac64a4561a0c5162d96d3f52ba0fb4d499b4180903cb954fde6bcd19dc4a4188a7f418a5c59836832bb8c47c9ee71bc214f9a8a7cff443f8d8f32b22648ae75b5eec94c1e4a197ee4829a1d78774d0cb0bdf60fd316d3bcfa2ba551385df5fbbadb7802dbffec0a1b96d583b81913e9b6c07b407be11f2827c9faef565e1ce67e947ec0f044b27939e5dab2628b4dbf3870e2682414c933a40837d558695ed37cedc1045308e74eb02a876308616f631559eab22b79d70c61678a5bfd5ead877fba86674f71581222042222ce8bef547100ce503558769508ee6ab1a201d50203010001a382017630820172301206092b060104018237150104050203010001302306092b060104018237150204160414f8c16bb77f77534af325371d4ea1267b0f207080301d0603551d0e0416041413adbf4309bd82709c8cd54f316ed522988a1bd4301906092b0601040182371402040c1e0a00530075006200430041300b0603551d0f040403020186300f0603551d130101ff040530030101ff301f0603551d2304183016801445665243e17e5811bfd64e9e2355083b3a226aa8305c0603551d1f045530533051a04fa04d864b687474703a2f2f63726c2e6d6963726f736f66742e636f6d2f706b692f63726c2f70726f64756374732f4d6963436f725468695061724d6172526f6f5f323031302d31302d30352e63726c306006082b0601050507010104543052305006082b060105050730028644687474703a2f2f7777772e6d6963726f736f66742e636f6d2f706b692f63657274732f4d6963436f725468695061724d6172526f6f5f323031302d31302d30352e637274300d06092a864886f70d01010b05000382020100350842ff30cccef7760cad1068583529463276277cef124127421b4aaa6d813848591355f3e95834a6160b82aa5dad82da808341068fb41df203b9f31a5d1bf15090f9b3558442281c20bdb2ae5114c5c0ac9795211c90db0ffc779e95739188cabdbd52b905500ddf579ea061ed0de56d25d9400f1740c8cea34ac24daf9a121d08548fbdc7bcb92b3d492b1f32fc6a21694f9bc87e4234fc3606178b8f2040c0b39a257527cdc903a3f65dd1e736547ab950b5d312d107bfbb74dfdc1e8f80d5ed18f42f14166b2fde668cb023e5c784d8edeac13382ad564b182df1689507cdcff072f0aebbdd8685982c214c332bf00f4af06887b592553275a16a826a3ca32511a4edadd704aecbd84059a084d1954c6291221a741d8c3d470e44a6e4b09b3435b1fab653a82c81eca40571c89db8bae81b4466e447540e8e567fb39f1698b286d0683e9023b52f5e8f50858dc68d825f41a1f42e0de099d26c75e4b669b52186fa07d1f6e24dd1daad2c77531e253237c76c52729586b0f135616a19f5b23b815056a6322dfea289f94286271855a182ca5a9bf830985414a64796252fc826e441941a5c023fe596e3855b3c3e3fbb47167255e22522b1d97be703062aa3f71e9046c3000dd61989e30e352762037115a6efd027a0a0593760f83894b8e07870f8ba4c868794f6e0ae0245ee65c2b6a37e69167507929bf5a6bc598358
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1498
          SignatureHeaderSize: 0
          SignatureSize: 1470
          Keys:
            - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
              SignatureData: 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
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1543
          SignatureHeaderSize: 0
          SignatureSize: 1515
          Keys:
            - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
              SignatureData: 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
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1081
          SignatureHeaderSize: 0
          SignatureSize: 1053
          Keys:
            - SignatureOwner: e58e05e2-5c43-4ef7-880b-3f06734eb36f
              SignatureData: 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
        - SignatureType: a5c059a1-94e4-4aa7-87b5-ab155c2bf072
          SignatureListSize: 1066
          SignatureHeaderSize: 0
          SignatureSize: 1038
          Keys:
            - SignatureOwner: e58e05e2-5c43-4ef7-880b-3f06734eb36f
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  - EventNum: 7
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_DRIVER_CONFIG
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: 'a044b4ce4a4dca9af312c897dc56ee1727c385eb88f7cfb9092b8265029d5b1e'
    EventSize: 3762
    Event:
      VariableName: d719b2cb-3d3a-4596-a3bc-dad00e67656f
      UnicodeNameLength: 3
      VariableDataLength: 3724
      UnicodeName: dbx
      VariableData:
        - SignatureType: c1c41626-504c-4092-aca9-41f936934328
          SignatureListSize: 3724
          SignatureHeaderSize: 0
          SignatureSize: 48
          Keys:
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              SignatureData: 80b4d96931bf0d02fd91a61e19d14f1da452e66db2408ca8604d411f92659f0a
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              SignatureData: f52f83a3fa9cfbd6920f722824dbe4034534d25b8507246b3b957dac6e1bce7a
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              SignatureData: 5391c3a2fb112102a6aa1edc25ae77e19f5d6f09cd09eeb2509922bfcd5992ea
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  - EventNum: 8
    PCRIndex: 7
    EventType: EV_SEPARATOR
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: 'df3f619804a92fdb4057192dc43dd748ea778adc52bc498ce80524c014b81119'
    EventSize: 4
    Event: '00000000'
  - EventNum: 9
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_AUTHORITY
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: '4d4a8e2c74133bbdc01a16eaf2dbb5d575afeb36f5d8dfcf609ae043909e2ee9'
    EventSize: 1608
    Event:
      VariableName: d719b2cb-3d3a-4596-a3bc-dad00e67656f
      UnicodeNameLength: 2
      VariableDataLength: 1572
      UnicodeName: db
      VariableData:
        - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
          SignatureData: 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
  - EventNum: 23
    PCRIndex: 7
    EventType: EV_EFI_VARIABLE_AUTHORITY
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: '30bf464ee37f1bc0c7b1a5bf25eced275347c3ab1492d5623ae9f7663be07dd5'
    EventSize: 1551
    Event:
      VariableName: d719b2cb-3d3a-4596-a3bc-dad00e67656f
      UnicodeNameLength: 2
      VariableDataLength: 1515
      UnicodeName: db
      VariableData:
        - SignatureOwner: 77fa9abd-0359-4d32-bd60-28f4e78f784b
          SignatureData: 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
pcrs:
  sha256:
    7: 0x15391ffc742d79dff13c11f33b4f11d116d9ba40b7290747ab0fb0b2e9404c9e

Multiple EV_EFI_VARIABLE_DRIVER_CONFIG events are written in order to record the current state of the Secure Boot configuration. The Platform Key (PK), Key Exchange Keys (KEK), the Authorised Signature Database (DB) and the Forbidden Signature Database (DBX) are all logged in order to allow remote attestation.

Finally, after an EV_SEPARATOR event, an EV_EFI_VARIABLE_AUTHORITY event is recorded every time an EFI Driver or EFI Boot Application is validated, containing the signature of the image matched against (if applicable).

PCR 4 records an EV_EFI_BOOT_SERVICES_APPLICATION event for every EFI Boot Application that is executed.

# Partial Windows Measured Boot log (PCR4, single event only)
# Converted from binary format using
# tpm2-tools' tpm2_eventlog
---
version: 2
events:
  - EventNum: 24
    PCRIndex: 4
    EventType: EV_EFI_BOOT_SERVICES_APPLICATION
    DigestCount: 1
    Digests:
      - AlgorithmId: sha256
        Digest: '2e80fa5623ea039ceb999558c98f82e261c03ab56cd5d40d276b2ec69e5fcb3b'
    EventSize: 188
    Event:
      ImageLocationInMemory: 0x82580018
      ImageLengthInMemory: 2830752
      ImageLinkTimeAddress: 0x10000000
      LengthOfDevicePath: 156
      DevicePath: 'PciRoot(0x0)/Pci(0x1,0x2)/Pci(0x0,0x0)/NVMe(0x1,00-25-38-B9-31-A4-FE-FD)/HD(1,GPT,d022bdc9-8147-4835-812a-8f0fa6365b22,0x800,0x32000)/\EFI\Microsoft\Boot\bootmgfw.efi'

This can also reveal if Windows was chain-loaded from a different bootloader, as there will be multiple EV_EFI_BOOT_SERVICES_APPLICATION events.

Anti-cheat engines can also detect if Windows is being executed through a hypervisor with the help of the TPM. If the host’s TPM is passed through to the guest, there will either be a second boot event in the TPM logs, or there will be one missing, and the EV_EFI_BOOT_SERVICES_APPLICATION will point to a different EFI application that isn’t validated by Microsoft’s KEK (as revealed by the EV_EFI_VARIABLE_AUTHORITY). If the TPM is virtualised (vTPM), the EKpub and EKcert validation will fail, as the EK won’t be signed by AMD or Intel.

Finally, Windows also has some proprietary information stored in OS-specific PCR banks. Of particular interest is PCR14 which contains a record of the public keys of boot authorities that Windows considered when validating kernel-level drivers. This allows anti-cheat providers to ensure that there isn’t a CustomKernelSigners licensing policy deployed.

This is an overview of what information is logged in each PCR for Windows specifically. Note that PCR 0 to 7 is reserved for firmware, while PCR 8 to 15 may vary depending on the OS/Bootloader. PCR 16 is normally reserved for debugging, and PCR 23 is reserved for Application Support⁵.

PCR	Description
PCR 0	Core System Firmware executable code
PCR 1	Core System Firmware data
PCR 2	Extended or pluggable executable code
PCR 3	Extended or pluggable firmware data
PCR 4	Boot Manager
PCR 5	GPT/Partition Table
PCR 6	Resume from S4 and S5 Power State Events
PCR 7	Secure Boot State
PCR 8	Initialised to 0 with no Extends (reserved for future use)
PCR 9	Initialised to 0 with no Extends (reserved for future use)
PCR 10	Initialised to 0 with no Extends (reserved for future use)
PCR 11	BitLocker access control
PCR 12	Data events and highly volatile events
PCR 13	Boot Module Details
PCR 14	Boot Authorities

In Windows, you can access the current and historical TPM event logs in binary form at the path %WINDIR%\Logs\MeasuredBoot\.

Under Linux, the PCR banks 8-15 may contain different information based on your bootloader. The Linux Userspace API Group publishes a useful PCR Registry. You can access the current TPM event logs at the path /sys/kernel/security/tpm0/binary_bios_measurements.

Remote Attestation

The last piece of the puzzle required to properly audit the boot environment is to retrieve the PCR bank values in a way that we can attest that they were not modified or altered by the user. This can be done via the TPM2_Quote TPM command with a given Attestation Key (AK).

Through a complicated dance of cryptographic operations (which are described in this draft guidance document from the TCG), the anti-cheat provider can verify the veracity of the TPM event logs, as well as validate that your EKpub is indeed tied to the actual fTPM that measured those events. If the anti-cheat provider, after verifying the TPM event logs, judges that your environment is in a valid state to connect to a protected game server, they can grant you a one-time use token to connect (cryptographically tied to your EK).

The anti-cheat provider would normally validate that your DB and DBX are up to date, and that no additional boot authorities were configured or used during Windows boot up to validate self-signed kernel-level drivers.

If the attestation is properly implemented on the side of the anti-cheat provider, barring any massive yet-undiscovered vulnerability in AMD or Intel’s fTPMs, this would be near impossible to bypass for cheaters. While this will not stop cheating by itself (vulnerabilities in the operating system, game or the anti-cheat engine will continue to be exploited), it would, however, prevent any pre-boot exploits and be extremely effective at preventing ban evasion.

What does it mean for Linux users?

It doesn’t change anything when it comes to anti-cheat using kernel-level components that are exclusive to Windows. If an anti-cheat provider decides to not support Linux, there’s not much we can do. That was the case before, it’s still the case now.

The only real impact is that we may see anti-cheat providers prevent access to the game if you chain-load Windows from GRUB2, systemd-boot or any other Linux bootloader. It would be an overreaction, as PCR14 would still allow them to ensure that only kernel-level drivers signed by Microsoft have been loaded. While annoying, you could boot Windows directly from your UEFI and avoid the issue altogether.

This can be easily remedied if you are using systemd-boot by adding the reboot-for-bitlocker yes option in your loader.conf. Unfortunately, GRUB2 doesn’t have any commands to set the BootNext UEFI variable, which would allow GRUB2 to simply reboot into Windows instead of chain-loading.

You will, however, have to configure your Linux installation to support Secure Boot. While some distributions ship with shim, I personally do not recommend it, as it adds another layer of keys to manage (Machine Owner Keys – MOK) and tends to be a hassle every single time your system uses non-free kernel modules (cough cough Nvidia).

Personally, enrolling your own Platform Key (PK) using sbctl and signing your boot images with hooks has been way easier to manage on the long run. You do a bit more work setting everything up, but then it is smooth sailing. No need to enroll a new MOK every time you have a kernel update. Set and forget. The Arch Linux wiki has a section on how to configure sbctl. You’ll need to adapt it to the specifics of your distribution if you are not using Arch.

We may see Linux anti-cheat engines in the future requiring TPM access to read the EKpub and EKcert. The good news is that this can be done entirely in user space, as a regular user as long as your user is a member of the tss group.

Another important thing to note that is that updates to the authorised signatures database (DB) and the forbidden signatures database (DBX) from Microsoft are distributed by the Linux Foundation via the Linux Vendor Firmware Service.

Conclusion

Secure Boot and a proper implementation of TPM remote attestation will be very effective at decreasing the number of cheaters that are not using hardware-based cheats. It will also make it considerably harder and costlier to do ban evasion. TPM attestation can also be done purely in user space, and doesn’t negatively impact your privacy.

Fewer cheaters and better enforcement of the integrity of the online environment are ultimately a good thing for gamers. I know personally that I’ve completely abandoned most online multiplayer games due to the rampant cheating and toxicity in those communities. Hopefully, this will help reduce the prevalence of cheaters. Riot’s numbers certainly seem to indicate so (even if I have zero interest in playing their games).

Sadly, while I believe that the only true solution to cheating is server-side behavioural analysis, we don’t currently have the means to easily implement that without the compute costs being prohibitive for developers. It also currently isn’t accurate enough.

Fighting cheating in online gaming requires anti-cheat developers to use a series of measures that, together, reduce the possibilities for cheat developers. There will not be a single solution to the problem, but by implementing a defence in depth approach, they can greatly help reduce the impact of cheating on players.

Usually it involves clearing the secure boot keys, and disabling secure boot. See your motherboard’s manual for details. ↩︎
There is a licensing policy called CustomKernelSigners which can be changed in order to allow custom keys, but this policy is only editable in a specific restricted SKU of Windows, and its use can be detected when inspecting the Measured Boot logs and the Platform Configuration Registers (PCR). ↩︎
Package name may vary depending on your distro. tpm2-tools is the package name on Arch Linux. ↩︎
The data that is used for hashing depends on the event type; the specifics are documented in various specification documents, notably the TCG PC Client Platform Firmware Profile Specification and TCG EFI Platform Specification. ↩︎
Refer to TCG PC Client Platform Firmware Profile Specification for more information. ↩︎