CWE-78
AllowedImproper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Abstraction: Base · Status: Stable
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.
8366 vulnerabilities reference this CWE, most recent first.
GHSA-279C-3782-HJV5
Vulnerability from github – Published: 2024-09-26 18:31 – Updated: 2024-09-26 18:31The device enables an unauthorized attacker to execute system commands with elevated privileges. This exploit is facilitated through the use of the 'getcommand' query within the application, allowing the attacker to gain root access.
{
"affected": [],
"aliases": [
"CVE-2024-9166"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-26T17:15:04Z",
"severity": "CRITICAL"
},
"details": "The device enables an unauthorized attacker to execute system commands with elevated privileges. This exploit is facilitated through the use of the \u0027getcommand\u0027 query within the application, allowing the attacker to gain root access.",
"id": "GHSA-279c-3782-hjv5",
"modified": "2024-09-26T18:31:44Z",
"published": "2024-09-26T18:31:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-9166"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/news-events/ics-advisories/icsa-24-270-03"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-27CV-WHXJ-627J
Vulnerability from github – Published: 2022-05-13 01:50 – Updated: 2022-05-13 01:50An issue was discovered on Teracue ENC-400 devices with firmware 2.56 and below. The login form passes user input directly to a shell command without any kind of escaping or validation in /usr/share/www/check.lp file. An attacker is able to perform command injection using the "password" parameter in the login form.
{
"affected": [],
"aliases": [
"CVE-2018-20218"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2019-03-21T16:00:00Z",
"severity": "CRITICAL"
},
"details": "An issue was discovered on Teracue ENC-400 devices with firmware 2.56 and below. The login form passes user input directly to a shell command without any kind of escaping or validation in /usr/share/www/check.lp file. An attacker is able to perform command injection using the \"password\" parameter in the login form.",
"id": "GHSA-27cv-whxj-627j",
"modified": "2022-05-13T01:50:59Z",
"published": "2022-05-13T01:50:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-20218"
},
{
"type": "WEB",
"url": "https://zxsecurity.co.nz/research.html"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2019/Feb/48"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-27FP-C3M4-PHWV
Vulnerability from github – Published: 2024-08-22 21:31 – Updated: 2024-08-22 21:31A vulnerability was found in TOTOLINK AC1200 T8 4.1.5cu.862_B20230228. It has been classified as critical. This affects the function setTracerouteCfg. The manipulation leads to os command injection. It is possible to initiate the attack remotely. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.
{
"affected": [],
"aliases": [
"CVE-2024-8077"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-08-22T20:15:11Z",
"severity": "MODERATE"
},
"details": "A vulnerability was found in TOTOLINK AC1200 T8 4.1.5cu.862_B20230228. It has been classified as critical. This affects the function setTracerouteCfg. The manipulation leads to os command injection. It is possible to initiate the attack remotely. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.",
"id": "GHSA-27fp-c3m4-phwv",
"modified": "2024-08-22T21:31:30Z",
"published": "2024-08-22T21:31:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-8077"
},
{
"type": "WEB",
"url": "https://github.com/hawkteam404/RnD_Public/blob/main/TOTOLink_AC1200_T8_OsCmdI_BOF.md"
},
{
"type": "WEB",
"url": "https://vuldb.com/?ctiid.275559"
},
{
"type": "WEB",
"url": "https://vuldb.com/?id.275559"
},
{
"type": "WEB",
"url": "https://www.totolink.net"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-27M7-FFHQ-JQRM
Vulnerability from github – Published: 2025-12-02 00:38 – Updated: 2025-12-02 00:38Summary
The MCPScanner class contains a critical Command Injection vulnerability in the cloneRepomethod. The application passes the user-supplied githubUrl argument directly to a system shell via execSync without sanitization. This allows an attacker to execute arbitrary commands on the host machine by appending shell metacharacters to the URL.
Details
The vulnerability exists in the src/scanner/MCPScanner.ts file within the cloneRepo method.
The code uses child_process.execSync to execute a git clone command:
Because execSync spawns a shell (defaulting to /bin/sh on Unix orcmd.exe on Windows), any shell metacharacters present in the url argument will be interpreted by the shell. The application does not validate that the url is a valid Git URL, nor does it sanitize input for shell metacharacters.
PoC
Install the package or clone the repository.
Run the scanner using the CLI (or invoke scanRepository programmatically).
Provide a malicious URL containing a command separator (e.g., ;, &, or |) and a system command.
payload : npm run scan:github "https://github.com/kapilduraphe/mcp-watch & calc.exe"
Impact
Severity: Critical
CVSS Score: 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) Description: This vulnerability allows an attacker to execute arbitrary code on the machine running the scanner.
If run by a developer locally, it compromises their workstation.
If deployed as a hosted scanning service, it grants the attacker full control over the server (RCE), leading to potential data exfiltration, service disruption, or further lateral movement within the infrastructure.
Context Dependent Risk:
Local CLI : If you run this tool locally on your own machine, you are "hacking yourself." The risk is limited unless you copy-paste a malicious URL sent by someone else (e.g., "Hey, check this repo scan: npm run scan "https://git./..; rm -rf /").
Web Service / CI Pipeline (Critical Risk): If this scanner is deployed as a web service (e.g., "Paste your repo URL to scan"), an attacker can take full control of the server immediately.
{
"affected": [
{
"package": {
"ecosystem": "npm",
"name": "mcp-watch"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "0.1.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2025-66401"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": true,
"github_reviewed_at": "2025-12-02T00:38:14Z",
"nvd_published_at": "2025-12-01T23:15:53Z",
"severity": "CRITICAL"
},
"details": "### Summary\nThe `MCPScanner ` class contains a critical Command Injection vulnerability in the `cloneRepo `method. The application passes the user-supplied githubUrl argument directly to a system shell via execSync without sanitization. This allows an attacker to execute arbitrary commands on the host machine by appending shell metacharacters to the URL.\n\n### Details\nThe vulnerability exists in the src/scanner/MCPScanner.ts file within the cloneRepo method.\n\n[https://github.com/kapilduraphe/mcp-watch/blob/0fca7228bd313ae5aa938d61311377e88ce6e682/src/scanner/McpScanner.ts#L181](https://github.com/kapilduraphe/mcp-watch/blob/0fca7228bd313ae5aa938d61311377e88ce6e682/src/scanner/McpScanner.ts#L181)\n\nThe code uses child_process.execSync to execute a git clone command:\n\nBecause execSync spawns a shell (defaulting to `/bin/sh` on Unix or` cmd.exe` on Windows), any shell metacharacters present in the url argument will be interpreted by the shell. The application does not validate that the url is a valid Git URL, nor does it sanitize input for shell metacharacters.\n\n### PoC\nInstall the package or clone the repository.\n\nRun the scanner using the CLI (or invoke scanRepository programmatically).\n\nProvide a malicious URL containing a command separator (e.g., ;, \u0026, or |) and a system command.\npayload : `npm run scan:github \"https://github.com/kapilduraphe/mcp-watch \u0026 calc.exe\"`\n\n\u003cimg width=\"1918\" height=\"1046\" alt=\"image\" src=\"https://github.com/user-attachments/assets/021c1dfa-3f87-483c-aecb-6939bcf9c925\" /\u003e\n\n\n\n### Impact\nSeverity: **Critical**\n\n**CVSS Score**: 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)\nDescription: This vulnerability allows an attacker to execute arbitrary code on the machine running the scanner.\n\nIf run by a developer locally, it compromises their workstation.\n\nIf deployed as a hosted scanning service, it grants the attacker full control over the server (RCE), leading to potential data exfiltration, service disruption, or further lateral movement within the infrastructure.\n\n**Context Dependent Risk:**\n\nLocal CLI : If you run this tool locally on your own machine, you are \"hacking yourself.\" The risk is limited unless you copy-paste a malicious URL sent by someone else (e.g., \"Hey, check this repo scan: npm run scan \"https://git./..; rm -rf /\").\n\n**Web Service / CI Pipeline (Critical Risk)**: If this scanner is deployed as a web service (e.g., \"Paste your repo URL to scan\"), an attacker can take full control of the server immediately.",
"id": "GHSA-27m7-ffhq-jqrm",
"modified": "2025-12-02T00:38:14Z",
"published": "2025-12-02T00:38:14Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/kapilduraphe/mcp-watch/security/advisories/GHSA-27m7-ffhq-jqrm"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66401"
},
{
"type": "WEB",
"url": "https://github.com/kapilduraphe/mcp-watch/commit/e7da78c5b4b960f8b66c254059ad9ebc544a91a6"
},
{
"type": "PACKAGE",
"url": "https://github.com/kapilduraphe/mcp-watch"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
],
"summary": "MCP Watch has a Critical Command Injection in cloneRepo allows Remote Code Execution (RCE) via malicious URL"
}
GHSA-27MM-RPGF-CVHW
Vulnerability from github – Published: 2023-07-06 15:30 – Updated: 2024-04-04 05:26An OS command injection vulnerability exists in the vtysh_ubus tcpdump_start_cb functionality of Milesight UR32L v32.3.0.5. A specially crafted HTTP request can lead to command execution. An attacker can send an HTTP request to trigger this vulnerability.
{
"affected": [],
"aliases": [
"CVE-2023-22653"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-07-06T15:15:11Z",
"severity": "HIGH"
},
"details": "An OS command injection vulnerability exists in the vtysh_ubus tcpdump_start_cb functionality of Milesight UR32L v32.3.0.5. A specially crafted HTTP request can lead to command execution. An attacker can send an HTTP request to trigger this vulnerability.",
"id": "GHSA-27mm-rpgf-cvhw",
"modified": "2024-04-04T05:26:48Z",
"published": "2023-07-06T15:30:33Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-22653"
},
{
"type": "WEB",
"url": "https://talosintelligence.com/vulnerability_reports/TALOS-2023-1714"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-27P8-M7H9-XCHC
Vulnerability from github – Published: 2025-09-26 09:31 – Updated: 2025-09-26 09:31Multiple robotic products by Unitree sharing a common firmware, including the Go2, G1, H1, and B2 devices, contain a command injection vulnerability. By setting a malicious string when configuring the on-board WiFi via a BLE module of an affected robot, then triggering a restart of the WiFi service, an attacker can ultimately trigger commands to be run as root via the wpa_supplicant_restart.sh shell script.
{
"affected": [],
"aliases": [
"CVE-2025-35027"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-09-26T07:15:41Z",
"severity": "HIGH"
},
"details": "Multiple robotic products by Unitree sharing a common firmware, including the Go2, G1, H1, and B2 devices, contain a command injection vulnerability. By setting a malicious string when configuring the on-board WiFi via a BLE module of an affected robot, then triggering a restart of the WiFi service, an attacker can ultimately trigger commands to be run as root via the wpa_supplicant_restart.sh shell script.",
"id": "GHSA-27p8-m7h9-xchc",
"modified": "2025-09-26T09:31:11Z",
"published": "2025-09-26T09:31:11Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-35027"
},
{
"type": "WEB",
"url": "https://github.com/Bin4ry/UniPwn"
},
{
"type": "WEB",
"url": "https://spectrum.ieee.org/unitree-robot-exploit"
},
{
"type": "WEB",
"url": "https://takeonme.org/cves/cve-2025-35027"
},
{
"type": "WEB",
"url": "https://www.cve.org/cverecord?id=CVE-2025-60017"
},
{
"type": "WEB",
"url": "https://www.cve.org/cverecord?id=CVE-2025-60250"
},
{
"type": "WEB",
"url": "https://x.com/committeeonccp/status/1971250635548033311"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-27RM-RRV9-67MV
Vulnerability from github – Published: 2026-03-31 15:31 – Updated: 2026-04-01 21:30Ridvay Code's command auto-approval module contains a critical OS command injection vulnerability that renders its whitelist security mechanism completely ineffective. The system relies on fragile regular expressions to parse command structures; while it attempts to intercept dangerous operations, it fails to account for standard Shell command substitution Ridvay Code (specifically$(...)and backticks ...). An attacker can construct a command such as git log --grep="$(malicious_command)", forcing Syntx to misidentify it as a safe git operation and automatically approve it. The underlying Shell prioritizes the execution of the malicious code injected within the arguments, resulting in Remote Code Execution without any user interaction.
{
"affected": [],
"aliases": [
"CVE-2026-30311"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-31T15:16:12Z",
"severity": "CRITICAL"
},
"details": "Ridvay Code\u0027s command auto-approval module contains a critical OS command injection vulnerability that renders its whitelist security mechanism completely ineffective. The system relies on fragile regular expressions to parse command structures; while it attempts to intercept dangerous operations, it fails to account for standard Shell command substitution Ridvay Code (specifically$(...)and backticks ...). An attacker can construct a command such as git log --grep=\"$(malicious_command)\", forcing Syntx to misidentify it as a safe git operation and automatically approve it. The underlying Shell prioritizes the execution of the malicious code injected within the arguments, resulting in Remote Code Execution without any user interaction.",
"id": "GHSA-27rm-rrv9-67mv",
"modified": "2026-04-01T21:30:27Z",
"published": "2026-03-31T15:31:56Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-30311"
},
{
"type": "WEB",
"url": "https://github.com/Secsys-FDU/LLM-Tool-Calling-CVEs/issues/8"
},
{
"type": "WEB",
"url": "https://ridvay.com"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-27XQ-W3JC-436C
Vulnerability from github – Published: 2024-02-05 15:30 – Updated: 2026-01-14 15:32An improper neutralization of special elements used in an os command ('os command injection') in Fortinet FortiSIEM version 7.1.0 through 7.1.1 and 7.0.0 through 7.0.2 and 6.7.0 through 6.7.8 and 6.6.0 through 6.6.3 and 6.5.0 through 6.5.2 and 6.4.0 through 6.4.2 allows attacker to execute unauthorized code or commands via via crafted API requests.
{
"affected": [],
"aliases": [
"CVE-2024-23109"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-02-05T14:15:59Z",
"severity": "CRITICAL"
},
"details": "An improper neutralization of special elements used in an os command (\u0027os command injection\u0027) in Fortinet FortiSIEM version 7.1.0 through 7.1.1 and 7.0.0 through 7.0.2 and 6.7.0 through 6.7.8 and 6.6.0 through 6.6.3 and 6.5.0 through 6.5.2 and 6.4.0 through 6.4.2 allows attacker to execute unauthorized code or commands via via\u00a0crafted API requests.",
"id": "GHSA-27xq-w3jc-436c",
"modified": "2026-01-14T15:32:56Z",
"published": "2024-02-05T15:30:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-23109"
},
{
"type": "WEB",
"url": "https://fortiguard.com/psirt/FG-IR-23-130"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-282M-CC46-HH73
Vulnerability from github – Published: 2021-12-10 00:00 – Updated: 2021-12-14 00:01An unauthenticated command injection vulnerability exists in the parameters of operation 10 in the controller_server service on Gryphon Tower routers. An unauthenticated remote attacker on the same network can execute commands as root on the device by sending a specially crafted malicious packet to the controller_server service on port 9999.
{
"affected": [],
"aliases": [
"CVE-2021-20140"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-12-09T16:15:00Z",
"severity": "HIGH"
},
"details": "An unauthenticated command injection vulnerability exists in the parameters of operation 10 in the controller_server service on Gryphon Tower routers. An unauthenticated remote attacker on the same network can execute commands as root on the device by sending a specially crafted malicious packet to the controller_server service on port 9999.",
"id": "GHSA-282m-cc46-hh73",
"modified": "2021-12-14T00:01:24Z",
"published": "2021-12-10T00:00:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-20140"
},
{
"type": "WEB",
"url": "https://www.tenable.com/security/research/tra-2021-51"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-2853-84MF-G278
Vulnerability from github – Published: 2024-09-06 18:31 – Updated: 2024-09-06 18:31An OS command injection vulnerability has been reported to affect several QNAP operating system versions. If exploited, the vulnerability could allow authenticated administrators to execute commands via a network.
We have already fixed the vulnerability in the following versions: QTS 5.1.8.2823 build 20240712 and later QuTS hero h5.1.8.2823 build 20240712 and later
{
"affected": [],
"aliases": [
"CVE-2024-21906"
],
"database_specific": {
"cwe_ids": [
"CWE-78"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-06T17:15:14Z",
"severity": "MODERATE"
},
"details": "An OS command injection vulnerability has been reported to affect several QNAP operating system versions. If exploited, the vulnerability could allow authenticated administrators to execute commands via a network.\n\nWe have already fixed the vulnerability in the following versions:\nQTS 5.1.8.2823 build 20240712 and later\nQuTS hero h5.1.8.2823 build 20240712 and later",
"id": "GHSA-2853-84mf-g278",
"modified": "2024-09-06T18:31:34Z",
"published": "2024-09-06T18:31:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-21906"
},
{
"type": "WEB",
"url": "https://www.qnap.com/en/security-advisory/qsa-24-33"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L",
"type": "CVSS_V3"
}
]
}
Mitigation
If at all possible, use library calls rather than external processes to recreate the desired functionality.
Mitigation MIT-22
Strategy: Sandbox or Jail
- Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
- OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations.
- This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise.
- Be careful to avoid CWE-243 and other weaknesses related to jails.
Mitigation
Strategy: Attack Surface Reduction
For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
Mitigation MIT-15
For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Mitigation MIT-4.3
Strategy: Libraries or Frameworks
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error.
Mitigation MIT-28
Strategy: Output Encoding
While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
Mitigation
If the program to be executed allows arguments to be specified within an input file or from standard input, then consider using that mode to pass arguments instead of the command line.
Mitigation MIT-27
Strategy: Parameterization
- If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
- Some languages offer multiple functions that can be used to invoke commands. Where possible, identify any function that invokes a command shell using a single string, and replace it with a function that requires individual arguments. These functions typically perform appropriate quoting and filtering of arguments. For example, in C, the system() function accepts a string that contains the entire command to be executed, whereas execl(), execve(), and others require an array of strings, one for each argument. In Windows, CreateProcess() only accepts one command at a time. In Perl, if system() is provided with an array of arguments, then it will quote each of the arguments.
Mitigation MIT-5
Strategy: Input Validation
- Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
- When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."
- Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
- When constructing OS command strings, use stringent allowlists that limit the character set based on the expected value of the parameter in the request. This will indirectly limit the scope of an attack, but this technique is less important than proper output encoding and escaping.
- Note that proper output encoding, escaping, and quoting is the most effective solution for preventing OS command injection, although input validation may provide some defense-in-depth. This is because it effectively limits what will appear in output. Input validation will not always prevent OS command injection, especially if you are required to support free-form text fields that could contain arbitrary characters. For example, when invoking a mail program, you might need to allow the subject field to contain otherwise-dangerous inputs like ";" and ">" characters, which would need to be escaped or otherwise handled. In this case, stripping the character might reduce the risk of OS command injection, but it would produce incorrect behavior because the subject field would not be recorded as the user intended. This might seem to be a minor inconvenience, but it could be more important when the program relies on well-structured subject lines in order to pass messages to other components.
- Even if you make a mistake in your validation (such as forgetting one out of 100 input fields), appropriate encoding is still likely to protect you from injection-based attacks. As long as it is not done in isolation, input validation is still a useful technique, since it may significantly reduce your attack surface, allow you to detect some attacks, and provide other security benefits that proper encoding does not address.
Mitigation MIT-21
Strategy: Enforcement by Conversion
When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs.
Mitigation MIT-32
Strategy: Compilation or Build Hardening
Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
Mitigation MIT-32
Strategy: Environment Hardening
Run the code in an environment that performs automatic taint propagation and prevents any command execution that uses tainted variables, such as Perl's "-T" switch. This will force the program to perform validation steps that remove the taint, although you must be careful to correctly validate your inputs so that you do not accidentally mark dangerous inputs as untainted (see CWE-183 and CWE-184).
Mitigation MIT-39
- Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success.
- If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files.
- Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not.
- In the context of OS Command Injection, error information passed back to the user might reveal whether an OS command is being executed and possibly which command is being used.
Mitigation
Strategy: Sandbox or Jail
Use runtime policy enforcement to create an allowlist of allowable commands, then prevent use of any command that does not appear in the allowlist. Technologies such as AppArmor are available to do this.
Mitigation MIT-29
Strategy: Firewall
Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Mitigation MIT-17
Strategy: Environment Hardening
Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Mitigation MIT-16
Strategy: Environment Hardening
When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
CAPEC-108: Command Line Execution through SQL Injection
An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
CAPEC-15: Command Delimiters
An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or denylist input validation, as opposed to allowlist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or denylist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.
CAPEC-43: Exploiting Multiple Input Interpretation Layers
An attacker supplies the target software with input data that contains sequences of special characters designed to bypass input validation logic. This exploit relies on the target making multiples passes over the input data and processing a "layer" of special characters with each pass. In this manner, the attacker can disguise input that would otherwise be rejected as invalid by concealing it with layers of special/escape characters that are stripped off by subsequent processing steps. The goal is to first discover cases where the input validation layer executes before one or more parsing layers. That is, user input may go through the following logic in an application: <parser1> --> <input validator> --> <parser2>. In such cases, the attacker will need to provide input that will pass through the input validator, but after passing through parser2, will be converted into something that the input validator was supposed to stop.
CAPEC-6: Argument Injection
An attacker changes the behavior or state of a targeted application through injecting data or command syntax through the targets use of non-validated and non-filtered arguments of exposed services or methods.
CAPEC-88: OS Command Injection
In this type of an attack, an adversary injects operating system commands into existing application functions. An application that uses untrusted input to build command strings is vulnerable. An adversary can leverage OS command injection in an application to elevate privileges, execute arbitrary commands and compromise the underlying operating system.