Summary
Hyperledger Indy's update process of a DID does not check who signs the request
Name
Updating a DID with a nym transaction will be written to the ledger if neither ROLE or VERKEY are being changed, regardless of sender.
Description
A malicious DID with no particular role can ask an update for another DID (but cannot modify its verkey or role). This is bad because:
- Any DID can write a nym transaction to the ledger (i.e., any DID can spam the ledger with nym transactions).
- Any DID can change any other DID's alias.
- The update transaction modifies the ledger metadata associated with a DID.
Expected vs Observed
We expect that if a DID (with no role) wants to update another DID (not its own or one it is the endorser), then the nodes should refuse the request. We can see that requirements in the Indy default auth_rules in Section "Who is the owner" in the last point of "Endorser using".
We observe that with a normal DID, we can update the field from for a random DID, for example, the one of a TRUSTEE. It creates then a new transaction on the ledger.
Explanation of the attack
We first begin to connect to the pool and open a wallet. Then, we will use a TRUSTEE (but can also be a STEWARD or an ENDORSER) DID V4SGRU86Z58d6TV7PBUe6f. We ask the information about V4SGRU86Z58d6TV7PBUe6f with a get-nym. We create a new DID V4SGRU86Z58d6TV7PBUe1a signed by V4SGRU86Z58d6TV7PBUe6f with no role. For the rest of the attack, we will use V4SGRU86Z58d6TV7PBUe1a to sign new transactions. We send a ledger nym did=V4SGRU86Z58d6TV7PBUe6f extra=hello to see if V4SGRU86Z58d6TV7PBUe1a can send an update of a TRUSTEE identity. When we ask information to the ledger about V4SGRU86Z58d6TV7PBUe6f, it answers that the from field is V4SGRU86Z58d6TV7PBUe1a (to compare with the first get-nym we did with from field = V4SGRU86Z58d6TV7PBUe6f). To see the log of the attack, I modified my indy-cli to print the json request and the json response directly on the terminal. You can find the log file indy.log in this archive.
Implementation notes
NymHandler method update_state, line 62. I think that we need to check if the DID which signs the transaction, owns the DID or is its endorser.
Steps to Reproduce
Environment
Ubuntu 18.04
Docker version 19.03.8
indy-cli
indy-ci Dockerfile is copied in this archive
To install indy-cli, run ./install_indy_cli.sh
Command
Here is the script to create the container, run the attack and remove the container and the image. Find below the command to execute each step separately.
./full_attack.sh
Installation of the environment
Install indy-cli and create an image with tag test from Dockerfile
./install.sh
Exploit
indy-cli proof_of_concept
Uninstallation of the environment
Suppress the container test and remove the image test
./uninstall.sh
Analysis
We are grateful to @alexandredeleze for discovering and responsibly disclosing the issue.
We were previously aware that any DID on the ledger can "update" the state (seqNo + txnTime) if it doesn't change the state data itself. We considered this a minor bug because only the seqNo and txnTime changed. But seeing that this can also affect the "parent" DID means that it has a higher severity.
Impact
CVE-2020-11093 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.12.4); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is CVE-2020-11093? CVE-2020-11093 is a high-severity security vulnerability in indy-node (pip), affecting versions >= 0, < 1.12.4. It is fixed in 1.12.4.
- How severe is CVE-2020-11093? CVE-2020-11093 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of indy-node are affected by CVE-2020-11093? indy-node (pip) versions >= 0, < 1.12.4 is affected.
- Is there a fix for CVE-2020-11093? Yes. CVE-2020-11093 is fixed in 1.12.4. Upgrade to this version or later.
- Is CVE-2020-11093 exploitable, and should I be worried? Whether CVE-2020-11093 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2020-11093 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2020-11093? Upgrade
indy-nodeto 1.12.4 or later.