CWE-22
Allowed-with-ReviewImproper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Abstraction: Base · Status: Stable
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
13235 vulnerabilities reference this CWE, most recent first.
GHSA-PC58-JH86-XJM9
Vulnerability from github – Published: 2022-05-24 17:11 – Updated: 2022-10-06 18:52Path Traversal in admin/imagepaster/image-renaming.php in Chadha PHPKB Standard Multi-Language 9 allows attackers to rename any file on the webserver using a dot-dot-slash sequence (../) via the POST parameter imgName (for the new name) and imgUrl (for the current file to be renamed).
{
"affected": [],
"aliases": [
"CVE-2020-10457"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2020-03-12T14:15:00Z",
"severity": "MODERATE"
},
"details": "Path Traversal in admin/imagepaster/image-renaming.php in Chadha PHPKB Standard Multi-Language 9 allows attackers to rename any file on the webserver using a dot-dot-slash sequence (../) via the POST parameter imgName (for the new name) and imgUrl (for the current file to be renamed).",
"id": "GHSA-pc58-jh86-xjm9",
"modified": "2022-10-06T18:52:06Z",
"published": "2022-05-24T17:11:13Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-10457"
},
{
"type": "WEB",
"url": "https://antoniocannito.it/phpkb1#arbitrary-file-renaming-cve-2020-10457"
},
{
"type": "WEB",
"url": "http://antoniocannito.it/?p=137#afr"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PC6V-7W9M-Q636
Vulnerability from github – Published: 2023-09-04 12:30 – Updated: 2024-04-04 07:25This vulnerability allows remote attackers to disclose sensitive information on affected installations of LG LED Assistant. Authentication is not required to exploit this vulnerability. The specific flaw exists within the /api/thumbnail endpoint. The issue results from the lack of proper validation of a user-supplied path prior to using it in file operations. An attacker can leverage this vulnerability to disclose information in the context of the current user.
{
"affected": [],
"aliases": [
"CVE-2023-4616"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-09-04T11:15:41Z",
"severity": "HIGH"
},
"details": "This vulnerability allows remote attackers to disclose sensitive information on affected installations of LG LED Assistant. Authentication is not required to exploit this vulnerability. The specific flaw exists within the /api/thumbnail endpoint. The issue results from the lack of proper validation of a user-supplied path prior to using it in file operations. An attacker can leverage this vulnerability to disclose information in the context of the current user.",
"id": "GHSA-pc6v-7w9m-q636",
"modified": "2024-04-04T07:25:49Z",
"published": "2023-09-04T12:30:18Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-4616"
},
{
"type": "WEB",
"url": "https://lgsecurity.lge.com/bulletins/idproducts#updateDetails"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-23-1223"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PC79-P8F4-VRV5
Vulnerability from github – Published: 2022-10-25 19:00 – Updated: 2022-10-31 19:00Esri ArcGIS Server versions 10.9.1 and prior have a path traversal vulnerability that may result in a denial of service by allowing a remote, authenticated attacker to overwrite internal ArcGIS Server directory.
{
"affected": [],
"aliases": [
"CVE-2022-38196"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-10-25T17:15:00Z",
"severity": "HIGH"
},
"details": "Esri ArcGIS Server versions 10.9.1 and prior have a path traversal vulnerability that may result in a denial of service by allowing a remote, authenticated attacker to overwrite internal ArcGIS Server directory.",
"id": "GHSA-pc79-p8f4-vrv5",
"modified": "2022-10-31T19:00:36Z",
"published": "2022-10-25T19:00:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-38196"
},
{
"type": "WEB",
"url": "https://www.esri.com/arcgis-blog/products/administration/administration/arcgis-server-security-2022-update-1-patch"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-PC7C-3RWX-PH2C
Vulnerability from github – Published: 2022-05-17 01:17 – Updated: 2025-04-20 03:44Directory traversal vulnerability in the file_get_contents function in SOPlanning 1.32 and earlier allows remote attackers to determine the existence of arbitrary files via a .. (dot dot) in a URL path parameter.
{
"affected": [],
"aliases": [
"CVE-2014-8676"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-08-31T22:29:00Z",
"severity": "MODERATE"
},
"details": "Directory traversal vulnerability in the file_get_contents function in SOPlanning 1.32 and earlier allows remote attackers to determine the existence of arbitrary files via a .. (dot dot) in a URL path parameter.",
"id": "GHSA-pc7c-3rwx-ph2c",
"modified": "2025-04-20T03:44:15Z",
"published": "2022-05-17T01:17:20Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2014-8676"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/37604"
},
{
"type": "WEB",
"url": "http://packetstormsecurity.com/files/132654/Simple-Online-Planning-Tool-1.3.2-XSS-SQL-Injection-Traversal.html"
},
{
"type": "WEB",
"url": "http://seclists.org/fulldisclosure/2015/Jul/44"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/75726"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PC7F-PHQ3-RQ3P
Vulnerability from github – Published: 2023-10-30 00:30 – Updated: 2023-11-07 21:30Peppermint Ticket Management through 0.2.4 allows remote attackers to read arbitrary files via a /api/v1/ticket/1/file/download?filepath=../ POST request.
{
"affected": [],
"aliases": [
"CVE-2023-46864"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-10-30T00:15:39Z",
"severity": "MODERATE"
},
"details": "Peppermint Ticket Management through 0.2.4 allows remote attackers to read arbitrary files via a /api/v1/ticket/1/file/download?filepath=../ POST request.",
"id": "GHSA-pc7f-phq3-rq3p",
"modified": "2023-11-07T21:30:24Z",
"published": "2023-10-30T00:30:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-46864"
},
{
"type": "WEB",
"url": "https://github.com/Peppermint-Lab/peppermint/issues/171"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PC82-3F32-R45V
Vulnerability from github – Published: 2022-05-24 19:02 – Updated: 2022-05-24 19:02A directory traversal vulnerability exists in Kyocera Printer d-COPIA253MF plus. Successful exploitation of this vulnerability could allow an attacker to retrieve or view arbitrary files from the affected server.
{
"affected": [],
"aliases": [
"CVE-2020-23575"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-05-10T23:15:00Z",
"severity": "HIGH"
},
"details": "A directory traversal vulnerability exists in Kyocera Printer d-COPIA253MF plus. Successful exploitation of this vulnerability could allow an attacker to retrieve or view arbitrary files from the affected server.",
"id": "GHSA-pc82-3f32-r45v",
"modified": "2022-05-24T19:02:10Z",
"published": "2022-05-24T19:02:10Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-23575"
},
{
"type": "WEB",
"url": "https://www.exploit-db.com/exploits/48561"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-PC82-CM8V-CJ54
Vulnerability from github – Published: 2024-05-03 03:30 – Updated: 2024-05-03 03:30LG Simple Editor deleteFolder Directory Traversal Arbitrary File Deletion Vulnerability. This vulnerability allows remote attackers to delete arbitrary files on affected installations of LG Simple Editor. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the deleteFolder method. The issue results from the lack of proper validation of a user-supplied path prior to using it in file operations. An attacker can leverage this vulnerability to delete files in the context of SYSTEM. Was ZDI-CAN-19921.
{
"affected": [],
"aliases": [
"CVE-2023-40494"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-03T03:15:23Z",
"severity": "HIGH"
},
"details": "LG Simple Editor deleteFolder Directory Traversal Arbitrary File Deletion Vulnerability. This vulnerability allows remote attackers to delete arbitrary files on affected installations of LG Simple Editor. Authentication is not required to exploit this vulnerability.\n\nThe specific flaw exists within the deleteFolder method. The issue results from the lack of proper validation of a user-supplied path prior to using it in file operations. An attacker can leverage this vulnerability to delete files in the context of SYSTEM. Was ZDI-CAN-19921.",
"id": "GHSA-pc82-cm8v-cj54",
"modified": "2024-05-03T03:30:58Z",
"published": "2024-05-03T03:30:58Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-40494"
},
{
"type": "WEB",
"url": "https://www.zerodayinitiative.com/advisories/ZDI-23-1200"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-PC99-QMG4-RCFF
Vulnerability from github – Published: 2023-01-20 16:00 – Updated: 2023-02-03 20:47Impact
The artifact server that stores artifacts from Github Action runs does not sanitize path inputs. This allows an attacker to download and overwrite arbitrary files on the host from a Github Action. This issue may lead to privilege escalation.
Issue 1: Arbitrary file upload in artifact server (GHSL-2023-004)
The /upload endpoint is vulnerable to path traversal as filepath is user controlled, and ultimately flows into os.Mkdir and os.Open.
router.PUT("/upload/:runId", func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {
itemPath := req.URL.Query().Get("itemPath")
runID := params.ByName("runId")
if req.Header.Get("Content-Encoding") == "gzip" {
itemPath += gzipExtension
}
filePath := fmt.Sprintf("%s/%s", runID, itemPath)
Issue 2: Arbitrary file download in artifact server (GHSL-2023-004)
The /artifact endpoint is vulnerable to path traversal as the path is variable is user controlled, and the specified file is ultimately returned by the server.
router.GET("/artifact/*path", func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {
path := params.ByName("path")[1:]
file, err := fsys.Open(path)
Proof of Concept
Below I have written a Github Action that will upload secret.txt into the folder above the specified artifact directory. The first call to curl will create the directory named 1 if it does not already exist, and the second call to curl will upload the secret.txt file to the directory above the specified artifact directory.
When testing this POC, the --artifact-server-path parameter must be passed to act in order to enable the artifact server.
Replace yourIPandPort with the IP and port of the server. An attacker can enumerate /proc/net/tcp in order to find the artifact server IP and port, but this is out of the scope of this report. Please let me know if you would like a copy of this script.
name: CI
on: push
jobs:
test:
runs-on: ubuntu-latest
steps:
- run: echo "Here are some secrets" > secret.txt
- run: curl http://<yourIPandPort>/upload/1?itemPath=secret.txt --upload-file secret.txt
- run: curl http://<yourIPandPort>/upload/1?itemPath=../../secret.txt --upload-file secret.txt
Remediation
- During implementation of Open and OpenAtEnd for FS, please ensure to use ValidPath() to check against path traversal. See more here: https://pkg.go.dev/io/fs#FS
- Clean the user-provided paths manually
Patches
Version 0.2.40 contains a patch.
Workarounds
Avoid use of artifact server with --artifact-server-path
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.2.39"
},
"package": {
"ecosystem": "Go",
"name": "github.com/nektos/act"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.2.40"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2023-22726"
],
"database_specific": {
"cwe_ids": [
"CWE-22",
"CWE-434"
],
"github_reviewed": true,
"github_reviewed_at": "2023-01-20T16:00:36Z",
"nvd_published_at": "2023-01-20T22:15:00Z",
"severity": "HIGH"
},
"details": "### Impact\nThe artifact server that stores artifacts from Github Action runs does not sanitize path inputs. This allows an attacker to download and overwrite arbitrary files on the host from a Github Action. This issue may lead to privilege escalation.\n\n\n#### Issue 1: Arbitrary file upload in artifact server (GHSL-2023-004)\nThe [/upload endpoint](https://github.com/nektos/act/blob/v0.2.35/pkg/artifacts/server.go#LL103C2-L103C2) is vulnerable to path traversal as filepath is user controlled, and ultimately flows into os.Mkdir and os.Open.\n\n```\nrouter.PUT(\"/upload/:runId\", func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {\n\t\titemPath := req.URL.Query().Get(\"itemPath\")\n\t\trunID := params.ByName(\"runId\")\n\n\t\tif req.Header.Get(\"Content-Encoding\") == \"gzip\" {\n\t\t\titemPath += gzipExtension\n\t\t}\n\n\t\tfilePath := fmt.Sprintf(\"%s/%s\", runID, itemPath)\n```\n\n#### Issue 2: Arbitrary file download in artifact server (GHSL-2023-004)\nThe [/artifact endpoint](https://github.com/nektos/act/blob/v0.2.35/pkg/artifacts/server.go#L245) is vulnerable to path traversal as the path is variable is user controlled, and the specified file is ultimately returned by the server.\n\n```\nrouter.GET(\"/artifact/*path\", func(w http.ResponseWriter, req *http.Request, params httprouter.Params) {\n\t\tpath := params.ByName(\"path\")[1:]\n\n\t\tfile, err := fsys.Open(path)\n```\n\n#### Proof of Concept\nBelow I have written a Github Action that will upload secret.txt into the folder above the specified artifact directory. The first call to curl will create the directory named 1 if it does not already exist, and the second call to curl will upload the secret.txt file to the directory above the specified artifact directory.\n\nWhen testing this POC, the `--artifact-server-path` parameter must be passed to act in order to enable the artifact server.\nReplace yourIPandPort with the IP and port of the server. An attacker can enumerate /proc/net/tcp in order to find the artifact server IP and port, but this is out of the scope of this report. Please let me know if you would like a copy of this script.\n\n```\nname: CI\non: push\n\njobs:\n test:\n runs-on: ubuntu-latest\n steps:\n - run: echo \"Here are some secrets\" \u003e secret.txt\n - run: curl http://\u003cyourIPandPort\u003e/upload/1?itemPath=secret.txt --upload-file secret.txt\n - run: curl http://\u003cyourIPandPort\u003e/upload/1?itemPath=../../secret.txt --upload-file secret.txt\n```\n\n### Remediation\n1. During implementation of [Open and OpenAtEnd for FS](https://github.com/nektos/act/blob/master/pkg/artifacts/server.go#L65), please ensure to use ValidPath() to check against path traversal. See more here: https://pkg.go.dev/io/fs#FS\n2. Clean the user-provided paths manually\n\n### Patches\nVersion 0.2.40 contains a patch.\n\n### Workarounds\nAvoid use of artifact server with `--artifact-server-path`",
"id": "GHSA-pc99-qmg4-rcff",
"modified": "2023-02-03T20:47:31Z",
"published": "2023-01-20T16:00:36Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nektos/act/security/advisories/GHSA-pc99-qmg4-rcff"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-22726"
},
{
"type": "WEB",
"url": "https://github.com/nektos/act/issues/1553"
},
{
"type": "WEB",
"url": "https://github.com/nektos/act/commit/63ae215071f94569d910964bdee866d91d6e3a10"
},
{
"type": "PACKAGE",
"url": "https://github.com/nektos/act"
},
{
"type": "WEB",
"url": "https://github.com/nektos/act/blob/master/pkg/artifacts/server.go#L65"
},
{
"type": "WEB",
"url": "https://github.com/nektos/act/blob/v0.2.35/pkg/artifacts/server.go#L245"
},
{
"type": "WEB",
"url": "https://github.com/nektos/act/blob/v0.2.35/pkg/artifacts/server.go#LL103C2-L103C2"
},
{
"type": "WEB",
"url": "https://github.com/nektos/act/releases/tag/v0.2.40"
},
{
"type": "ADVISORY",
"url": "https://securitylab.github.com/advisories/GHSL-2023-004_act"
}
],
"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"
}
],
"summary": "act vulnerable to arbitrary file upload in artifact server"
}
GHSA-PCCR-Q7V9-5F27
Vulnerability from github – Published: 2022-01-06 21:32 – Updated: 2022-08-11 18:41An Improper Input Validation vulnerability in DataImportHandler of Apache Solr allows an attacker to provide a Windows UNC path resulting in an SMB network call being made from the Solr host to another host on the network. If the attacker has wider access to the network, this may lead to SMB attacks, which may result in: * The exfiltration of sensitive data such as OS user hashes (NTLM/LM hashes), * In case of misconfigured systems, SMB Relay Attacks which can lead to user impersonation on SMB Shares or, in a worse-case scenario, Remote Code Execution This issue affects all Apache Solr versions prior to 8.11.1. This issue only affects Windows.
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "org.apache.solr:solr-parent"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "8.11.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2021-44548"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-22",
"CWE-40"
],
"github_reviewed": true,
"github_reviewed_at": "2022-01-05T17:54:06Z",
"nvd_published_at": "2021-12-23T09:15:00Z",
"severity": "CRITICAL"
},
"details": "An Improper Input Validation vulnerability in DataImportHandler of Apache Solr allows an attacker to provide a Windows UNC path resulting in an SMB network call being made from the Solr host to another host on the network. If the attacker has wider access to the network, this may lead to SMB attacks, which may result in: * The exfiltration of sensitive data such as OS user hashes (NTLM/LM hashes), * In case of misconfigured systems, SMB Relay Attacks which can lead to user impersonation on SMB Shares or, in a worse-case scenario, Remote Code Execution This issue affects all Apache Solr versions prior to 8.11.1. This issue only affects Windows.",
"id": "GHSA-pccr-q7v9-5f27",
"modified": "2022-08-11T18:41:45Z",
"published": "2022-01-06T21:32:35Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-44548"
},
{
"type": "PACKAGE",
"url": "https://github.com/apache/solr"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20220114-0005"
},
{
"type": "WEB",
"url": "https://solr.apache.org/security.html#cve-2021-44548-apache-solr-information-disclosure-vulnerability-through-dataimporthandler"
}
],
"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": "Apache Solr Improper Input Validation and Path Traversal"
}
GHSA-PCGV-6RCF-4897
Vulnerability from github – Published: 2022-05-13 01:53 – Updated: 2022-05-13 01:53Blue River Mura CMS before v7.0.7029 supports inline function calls with an [m] tag and [/m] end tag, without proper restrictions on file types or pathnames, which allows remote attackers to execute arbitrary code via an [m]$.dspinclude("../pathname/executable.jpeg")[/m] approach, where executable.jpeg contains ColdFusion Markup Language code. This can be exploited in conjunction with a CKFinder feature that allows file upload.
{
"affected": [],
"aliases": [
"CVE-2018-7486"
],
"database_specific": {
"cwe_ids": [
"CWE-22"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2018-02-26T14:29:00Z",
"severity": "HIGH"
},
"details": "Blue River Mura CMS before v7.0.7029 supports inline function calls with an [m] tag and [/m] end tag, without proper restrictions on file types or pathnames, which allows remote attackers to execute arbitrary code via an [m]$.dspinclude(\"../pathname/executable.jpeg\")[/m] approach, where executable.jpeg contains ColdFusion Markup Language code. This can be exploited in conjunction with a CKFinder feature that allows file upload.",
"id": "GHSA-pcgv-6rcf-4897",
"modified": "2022-05-13T01:53:23Z",
"published": "2022-05-13T01:53:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2018-7486"
},
{
"type": "WEB",
"url": "http://bekhzod0725.github.io/cybersecurity/2018/02/16/exploiting-muracms.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
Mitigation MIT-5.1
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 validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434.
- Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would be removed from the original string, but the remaining characters would still form the "../" string.
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-20.1
Strategy: Input Validation
- Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
- Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes:
- realpath() in C
- getCanonicalPath() in Java
- GetFullPath() in ASP.NET
- realpath() or abs_path() in Perl
- realpath() in PHP
Mitigation MIT-4
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 [REF-1482].
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-21.1
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.
- For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
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 MIT-34
Strategy: Attack Surface Reduction
- Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately.
- This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
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 path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
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-126: Path Traversal
An adversary uses path manipulation methods to exploit insufficient input validation of a target to obtain access to data that should be not be retrievable by ordinary well-formed requests. A typical variety of this attack involves specifying a path to a desired file together with dot-dot-slash characters, resulting in the file access API or function traversing out of the intended directory structure and into the root file system. By replacing or modifying the expected path information the access function or API retrieves the file desired by the attacker. These attacks either involve the attacker providing a complete path to a targeted file or using control characters (e.g. path separators (/ or \) and/or dots (.)) to reach desired directories or files.
CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic
This attack targets the encoding of the URL combined with the encoding of the slash characters. An attacker can take advantage of the multiple ways of encoding a URL and abuse the interpretation of the URL. A URL may contain special character that need special syntax handling in order to be interpreted. Special characters are represented using a percentage character followed by two digits representing the octet code of the original character (%HEX-CODE). For instance US-ASCII space character would be represented with %20. This is often referred as escaped ending or percent-encoding. Since the server decodes the URL from the requests, it may restrict the access to some URL paths by validating and filtering out the URL requests it received. An attacker will try to craft an URL with a sequence of special characters which once interpreted by the server will be equivalent to a forbidden URL. It can be difficult to protect against this attack since the URL can contain other format of encoding such as UTF-8 encoding, Unicode-encoding, etc.
CAPEC-76: Manipulating Web Input to File System Calls
An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
CAPEC-78: Using Escaped Slashes in Alternate Encoding
This attack targets the use of the backslash in alternate encoding. An adversary can provide a backslash as a leading character and causes a parser to believe that the next character is special. This is called an escape. By using that trick, the adversary tries to exploit alternate ways to encode the same character which leads to filter problems and opens avenues to attack.
CAPEC-79: Using Slashes in Alternate Encoding
This attack targets the encoding of the Slash characters. An adversary would try to exploit common filtering problems related to the use of the slashes characters to gain access to resources on the target host. Directory-driven systems, such as file systems and databases, typically use the slash character to indicate traversal between directories or other container components. For murky historical reasons, PCs (and, as a result, Microsoft OSs) choose to use a backslash, whereas the UNIX world typically makes use of the forward slash. The schizophrenic result is that many MS-based systems are required to understand both forms of the slash. This gives the adversary many opportunities to discover and abuse a number of common filtering problems. The goal of this pattern is to discover server software that only applies filters to one version, but not the other.