Attack Chain

1. Attacker publishes the mysten-metrics crate to crates.io.
2. A developer adds mysten-metrics as a dependency to their project.
3. The developer builds the project using cargo build.
4. As part of the build process, the malicious build script within mysten-metrics is executed.
5. The build script collects sensitive data from the build environment (e.g., environment variables, file contents, system information).
6. The build script attempts to exfiltrate the collected data to a remote attacker-controlled server. The exact exfiltration method is not specified, but could involve HTTP/S requests or DNS tunneling.
7. The attacker receives the exfiltrated data from the compromised build machine.

Impact

The successful execution of the malicious build script could lead to the exposure of sensitive information, including API keys, credentials, source code, and other confidential data present on the build machine. This data could be used to compromise the developer’s infrastructure, intellectual property, and customer data. Since there were no known usages, the impact was contained by its early removal.

Recommendation

• Implement integrity checks for all third-party dependencies to identify and prevent the use of malicious packages.
• Monitor network connections originating from build processes for suspicious outbound traffic, as this could indicate data exfiltration. Create network connection rules.
• Implement file integrity monitoring on build machines to detect unauthorized modifications to files during the build process.

Attack Chain

1. A developer adds the malicious sui-execution-cut crate as a dependency to their Rust project.
2. During the build process, the cargo build system executes the build script embedded within the sui-execution-cut crate.
3. The build script executes a series of commands designed to gather sensitive information from the build environment.
4. The script establishes an outbound network connection to a remote server controlled by the attacker.
5. The gathered data is transmitted to the attacker’s server via HTTP POST or a similar method.
6. The attacker receives the exfiltrated data, which could include environment variables, file contents, or other sensitive information.
7. The attacker analyzes the stolen data for valuable secrets, credentials, or intellectual property.

Impact

The sui-execution-cut crate, if used, could have compromised developer machines by exfiltrating sensitive data during the build process. Although the crate was quickly removed and showed no signs of usage, a successful attack of this nature could lead to the exposure of secrets, credentials, and intellectual property. The lack of usage limits the impact, but the nature of supply chain attacks makes even low-usage crates a potential risk.

Recommendation

• Monitor for unexpected network connections originating from build processes, especially connections to unknown or suspicious domains. Use the “Detect Suspicious Outbound Connections from Build Processes” Sigma rule.
• Implement strict dependency review processes to identify and prevent the introduction of malicious packages into your software supply chain.
• Continuously monitor crates.io and other package repositories for reports of malicious packages and promptly remove them from your dependencies if identified.

Attack Chain

1. An attacker crafts a malicious application or exploits an existing application using the vulnerable rust-openssl crate.
2. The attacker triggers one of the vulnerable callback functions (set_psk_client_callback, set_psk_server_callback, set_cookie_generate_cb, or set_stateless_cookie_generate_cb).
3. The vulnerable callback function executes the user-provided closure.
4. The user-provided closure returns a usize value indicating the intended length of the data to be written to the output buffer.
5. The FFI trampoline forwards this usize value directly to OpenSSL, bypassing bounds checking against the actual buffer size.
6. If the returned usize exceeds the allocated buffer size, OpenSSL writes beyond the buffer boundary, leading to a buffer overflow.
7. The buffer overflow allows the attacker to read adjacent memory regions or overwrite data, potentially leaking sensitive information or corrupting program state.
8. Successful exploitation could lead to information disclosure, denial of service, or potentially arbitrary code execution.

Impact

Successful exploitation of this vulnerability could lead to information disclosure, denial of service, or potentially arbitrary code execution. Given the widespread use of the rust-openssl crate in various applications, the impact could be significant, affecting numerous services and potentially exposing sensitive data. The vulnerability allows for memory leakage to peers which could have broad consequences.

Recommendation

• Upgrade to rust-openssl version 0.10.78 or later to patch the vulnerability (reference: https://github.com/rust-openssl/rust-openssl/releases/tag/openssl-v0.10.78).
• Implement input validation and sanitization within user-provided closures to ensure that the returned usize value does not exceed the allocated buffer size, mitigating the risk even in vulnerable versions.

Attack Chain

1. An attacker establishes a standard libp2p session with a target node using TCP + Noise for encryption.
2. The attacker negotiates a stream multiplexer protocol such as mplex or yamux.
3. The attacker opens a Gossipsub stream with the target node to initiate communication.
4. The attacker sends an RPC (Remote Procedure Call) containing a ControlPrune message.
5. The ControlPrune message includes a crafted backoff value set near the maximum representable value for an i64 integer (e.g., 9223372036854674580). The attacker chooses this value relative to the victim’s uptime.
6. The target node parses the backoff value from the protobuf message and processes it using Behaviour::handle_prune().
7. The backoff value is stored after a checked addition to ensure it’s valid, however the near-maximum value is still retained.
8. On the next heartbeat, the node attempts to calculate the expiry time by adding a slack value to the stored backoff_time using unchecked addition, which results in an integer overflow, causing a panic and crashing the application.

Impact

This vulnerability results in a remote, unauthenticated denial of service. Any application exposing an affected libp2p-gossipsub listener can be crashed by a network-reachable peer. The crash occurs during heartbeat processing, not immediately upon receiving the PRUNE message. The attack can be repeated by reconnecting to the target and replaying the crafted PRUNE message. This could lead to service disruptions and potential data loss if the application does not handle crashes gracefully. The number of potential victims is significant, encompassing any application utilizing vulnerable versions of the libp2p-gossipsub library.

Recommendation

• Upgrade the libp2p-gossipsub dependency to version 0.49.4 or later to patch the unchecked arithmetic operation that causes the overflow.
• Deploy the Sigma rule “Detect libp2p Gossipsub PRUNE with Large Backoff” to identify potential exploitation attempts by monitoring network traffic for unusually large backoff values in PRUNE messages.
• Enable network connection logging to capture details of libp2p sessions and identify potential malicious peers attempting to exploit this vulnerability (logsource: network_connection).

Attack Chain

This threat brief focuses on the analysis of Rust binaries, not a specific attack chain. However, understanding the structure of these binaries is crucial for analyzing attacks leveraging them. The following steps outline a general reverse engineering process applicable to any binary, with considerations specific to Rust:

1. Initial Reconnaissance: Obtain the Rust binary and gather basic information such as file type, size, and compilation timestamp using tools like file and strings.
2. Metadata Analysis: Examine the binary’s metadata section to identify Rust version, crate dependencies, and potentially debug symbols. This can be done using tools like objdump or specialized Rust metadata parsers.
3. String Extraction: Extract embedded strings from the binary. Note that Rust often uses UTF-8 encoding for strings, so ensure your tools support this encoding.
4. Function Identification: Identify key functions such as main, and any other functions related to suspicious behavior. Tools like IDA Pro or Ghidra can be used for disassembly and function analysis.
5. Control Flow Analysis: Analyze the control flow of the program, paying attention to function calls and branching logic. Rust’s ownership and borrowing system can make control flow more complex than in C/C++.
6. Dependency Analysis: Identify and analyze any external crates (libraries) used by the binary. These crates may contain known vulnerabilities or malicious code.
7. Behavioral Analysis: Execute the binary in a controlled environment (sandbox) to observe its behavior, including file system access, network connections, and registry modifications.
8. Detection Rule Creation: Based on the reverse engineering and behavioral analysis, create detection rules for identifying similar malicious Rust binaries.

Impact

The increasing use of Rust in malware development poses a challenge for security analysts. Successful reverse engineering and understanding of Rust binaries are crucial for detecting and mitigating threats. Failure to adapt to this trend could lead to a decreased ability to identify and respond to novel malware strains.

Recommendation

• Familiarize detection engineers with the structure and characteristics of Rust binaries as described in the JPCERT/CC study to improve reverse engineering capabilities.
• Implement the Sigma rules provided below to detect suspicious behaviors commonly associated with potentially malicious binaries, adjusting thresholds and whitelists as needed for your environment.
• Utilize tools capable of parsing Rust metadata to extract crate dependencies and other useful information from Rust binaries during analysis, as described in the “Metadata Analysis” step above.

Attack Chain

1. An attacker crafts a Rust application that utilizes the rust-openssl crate.
2. The application initiates a digest operation using EVP_DigestInit() to set up the message digest context.
3. The application feeds data into the digest context using EVP_DigestUpdate().
4. The application calls MdCtxRef::digest_final() via safe Rust.
5. Internally, EVP_DigestFinal() is called without proper bounds checking.
6. EVP_DigestFinal() attempts to write EVP_MD_CTX_size(ctx) bytes to the out buffer.
7. If out is smaller than the expected size, a stack-based buffer overflow occurs as data is written beyond the allocated memory region.
8. This overflow overwrites adjacent memory on the stack, potentially corrupting critical program data or control flow structures, leading to crashes or arbitrary code execution.

Impact

Successful exploitation of this vulnerability allows an attacker to potentially achieve arbitrary code execution within the context of the affected application. This could lead to complete system compromise, data breaches, or denial-of-service conditions. Given that the vulnerability is reachable from safe Rust, applications relying on vulnerable versions of the rust-openssl crate are at risk. The vulnerability can cause stack corruption, leading to unpredictable behavior and potential application crashes.

Recommendation

• Upgrade the rust-openssl crate to version 0.10.78 or later to remediate CVE-2026-41681.
• Implement robust input validation and size checks when using the rust-openssl crate, specifically when handling digest operations, to prevent buffer overflows.

Attack Chain

1. An attacker crafts a malicious application using the rust-openssl crate.
2. The application uses Deriver::derive or PkeyCtxRef::derive with an X25519, X448, DH, or HKDF-extract key agreement algorithm.
3. The application provides a buffer smaller than the expected output size of the key derivation function (32 bytes for X25519, 56 bytes for X448, prime-size bytes for DH).
4. The EVP_PKEY_derive function in OpenSSL 1.1.x is called without proper buffer length validation.
5. The key derivation function writes the full shared secret to the undersized buffer.
6. A heap or stack buffer overflow occurs, overwriting adjacent memory.
7. The attacker gains control of the application’s execution flow.
8. The attacker executes arbitrary code on the target system.

Impact

Successful exploitation of this vulnerability can lead to arbitrary code execution within the context of the vulnerable application. This could allow an attacker to gain complete control of the affected system. The number of victims depends on the prevalence of vulnerable rust-openssl versions being used with OpenSSL 1.1.x. Sectors that rely on rust-openssl for cryptographic operations are at higher risk.

Recommendation

• Upgrade the rust-openssl crate to version >= 0.10.78 to patch the vulnerability (see Overview).
• If upgrading rust-openssl is not immediately feasible, ensure that OpenSSL is upgraded to version 3.x, where the buffer length is checked (see Overview).
• Implement runtime checks to validate buffer lengths before calling Deriver::derive and PkeyCtxRef::derive when using X25519, X448, DH, or HKDF-extract (see Attack Chain).
• Deploy the Sigma rule provided below to detect potential exploitation attempts (see Rules).

Attack Chain

1. Attacker identifies a Nimiq Block instance running a vulnerable version (<= 0.2.0) of the rust/nimiq-block package.
2. The attacker crafts a malicious MultiSignature.signers payload.
3. The malicious payload contains out-of-range indices spaced by 65536. These indices are specifically designed to inflate the BitSet.len() calculation used in the quorum check.
4. During verification within SkipBlockProof::verify, the usize indices are cast to u16 (slot as u16) for slot lookup.
5. Due to the u16 truncation, the out-of-range indices collide onto the same in-range slot. This creates an artificial aggregation of signatures.
6. The attacker multiplies a single BLS signature by a factor to match the inflated len() value.
7. The manipulated SkipBlockProof passes the quorum check due to the inflated len() and signature aggregation.
8. The malicious skip block is accepted, potentially leading to consensus manipulation or other attacks on the blockchain.

Impact

Successful exploitation of this vulnerability allows a malicious validator to bypass the standard quorum requirements for skip block proof verification. This means that a single compromised validator or a small group of colluding validators can inject fraudulent blocks into the blockchain, potentially leading to double-spending, denial-of-service, or other attacks that compromise the integrity and availability of the Nimiq blockchain. Given the severity of these potential outcomes, this vulnerability poses a critical risk to any system relying on affected versions of Nimiq Block.

Recommendation

• Upgrade to rust/nimiq-block version 1.3.0 or later, which includes the fix for CVE-2026-33471.
• Monitor network traffic for anomalies related to skip block submissions, focusing on unusually large MultiSignature.signers payloads with indices spaced by multiples of 65536. Create a network monitoring rule.