Mozilla Foundation Security Advisory 2017-18

Security vulnerabilities fixed in Firefox 55

Announced August 8, 2017 Impact critical Products Firefox Fixed in Firefox 55

# CVE-2017-7798: XUL injection in the style editor in devtools Reporter Frederik Braun Impact critical Description The Developer Tools feature suffers from a XUL injection vulnerability due to improper sanitization of the web page source code. In the worst case, this could allow arbitrary code execution when opening a malicious page with the style editor tool. References Bug 1371586, 1372112

# CVE-2017-7800: Use-after-free in WebSockets during disconnection Reporter Looben Yang Impact critical Description A use-after-free vulnerability can occur in WebSockets when the object holding the connection is freed before the disconnection operation is finished. This results in an exploitable crash. References Bug 1374047

# CVE-2017-7801: Use-after-free with marquee during window resizing Reporter Nils Impact critical Description A use-after-free vulnerability can occur while re-computing layout for a marquee element during window resizing where the updated style object is freed while still in use. This results in a potentially exploitable crash. References Bug 1371259

# CVE-2017-7809: Use-after-free while deleting attached editor DOM node Reporter Nils Impact high Description A use-after-free vulnerability can occur when an editor DOM node is deleted prematurely during tree traversal while still bound to the document. This results in a potentially exploitable crash. References Bug 1380284

# CVE-2017-7784: Use-after-free with image observers Reporter Nils Impact high Description A use-after-free vulnerability can occur when reading an image observer during frame reconstruction after the observer has been freed. This results in a potentially exploitable crash. References Bug 1376087

# CVE-2017-7802: Use-after-free resizing image elements Reporter Nils Impact high Description A use-after-free vulnerability can occur when manipulating the DOM during the resize event of an image element. If these elements have been freed due to a lack of strong references, a potentially exploitable crash may occur when the freed elements are accessed. References Bug 1378147

# CVE-2017-7785: Buffer overflow manipulating ARIA attributes in DOM Reporter Nils Impact high Description A buffer overflow can occur when manipulating Accessible Rich Internet Applications (ARIA) attributes within the DOM. This results in a potentially exploitable crash. References Bug 1356985

# CVE-2017-7786: Buffer overflow while painting non-displayable SVG Reporter Nils Impact high Description A buffer overflow can occur when the image renderer attempts to paint non-displayable SVG elements. This results in a potentially exploitable crash. References Bug 1365189

# CVE-2017-7806: Use-after-free in layer manager with SVG Reporter Nils Impact high Description A use-after-free vulnerability can occur when the layer manager is freed too early when rendering specific SVG content, resulting in a potentially exploitable crash. References Bug 1378113

# CVE-2017-7753: Out-of-bounds read with cached style data and pseudo-elements Reporter SkyLined Impact high Description An out-of-bounds read occurs when applying style rules to pseudo-elements, such as ::first-line, using cached style data. References Bug 1353312

# CVE-2017-7787: Same-origin policy bypass with iframes through page reloads Reporter Oliver Wagner Impact high Description Same-origin policy protections can be bypassed on pages with embedded iframes during page reloads, allowing the iframes to access content on the top level page, leading to information disclosure. References Bug 1322896

# CVE-2017-7807: Domain hijacking through AppCache fallback Reporter Mathias Karlsson Impact high Description A mechanism that uses AppCache to hijack a URL in a domain using fallback by serving the files from a sub-path on the domain. This has been addressed by requiring fallback files be inside the manifest directory. References Bug 1376459

# CVE-2017-7792: Buffer overflow viewing certificates with an extremely long OID Reporter Fraser Tweedale Impact high Description A buffer overflow will occur when viewing a certificate in the certificate manager if the certificate has an extremely long object identifier (OID). This results in a potentially exploitable crash. References Bug 1368652

# CVE-2017-7804: Memory protection bypass through WindowsDllDetourPatcher Reporter Stephen Fewer Impact high Description The destructor function for the WindowsDllDetourPatcher class can be re-purposed by malicious code in concert with another vulnerability to write arbitrary data to an attacker controlled location in memory. This can be used to bypass existing memory protections in this situation.

Note: This attack only affects Windows operating systems. Other operating systems are not affected. References Bug 1372849

# CVE-2017-7791: Spoofing following page navigation with data: protocol and modal alerts Reporter Jose María Acuña Impact moderate Description On pages containing an iframe, the data: protocol can be used to create a modal alert that will render over arbitrary domains following page navigation, spoofing of the origin of the modal alert from the iframe content. References Bug 1365875

# CVE-2017-7808: CSP information leak with frame-ancestors containing paths Reporter Jun Kokatsu Impact moderate Description A content security policy (CSP) frame-ancestors directive containing origins with paths allows for comparisons against those paths instead of the origin. This results in a cross-origin information leak of this path information. References Bug 1367531

# CVE-2017-7782: WindowsDllDetourPatcher allocates memory without DEP protections Reporter Arthur Edelstein Impact moderate Description An error in the WindowsDllDetourPatcher where a RWX ("Read/Write/Execute") 4k block is allocated but never protected, violating DEP protections.

Note: This attack only affects Windows operating systems. Other operating systems are not affected. References Bug 1344034

# CVE-2017-7781: Elliptic curve point addition error when using mixed Jacobian-affine coordinates Reporter Antonio Sanso Impact moderate Description An error occurs in the elliptic curve point addition algorithm that uses mixed Jacobian-affine coordinates where it can yield a result POINT_AT_INFINITY when it should not. A man-in-the-middle attacker could use this to interfere with a connection, resulting in an attacked party computing an incorrect shared secret. References Bug 1352039

# CVE-2017-7794: Linux file truncation via sandbox broker Reporter Jann Horn Impact moderate Description On Linux systems, if the content process is compromised, the sandbox broker will allow files to be truncated even though the sandbox explicitly only has read access to the local file system and no write permissions.

Note: This attack only affects the Linux operating system. Other operating systems are not affected. References Bug 1374281

# CVE-2017-7803: CSP containing 'sandbox' improperly applied Reporter Rhys Enniks Impact moderate Description When a page’s content security policy (CSP) header contains a sandbox directive, other directives are ignored. This results in the incorrect enforcement of CSP. References Bug 1377426

# CVE-2017-7799: Self-XSS XUL injection in about:webrtc Reporter Frederik Braun Impact moderate Description JavaScript in the about:webrtc page is not sanitized properly being assigned to innerHTML . Data on this page is supplied by WebRTC usage and is not under third-party control, making this difficult to exploit, but the vulnerability could possibly be used for a cross-site scripting (XSS) attack. References Bug 1372509

# CVE-2017-7783: DOS attack through long username in URL Reporter Amit Sangra Impact low Description If a long user name is used in a username/password combination in a site URL (such as http://UserName:Password@example.com ), the resulting modal prompt will hang in a non-responsive state or crash, causing a denial of service. References Bug 1360842

# CVE-2017-7788: Sandboxed about:srcdoc iframes do not inherit CSP directives Reporter Muneaki Nishimura Impact low Description When an iframe has a sandbox attribute and its content is specified using srcdoc , that content does not inherit the containing page's Content Security Policy (CSP) as it should unless the sandbox attribute included allow-same-origin . References Bug 1073952

# CVE-2017-7789: Failure to enable HSTS when two STS headers are sent for a connection Reporter Muneaki Nishimura Impact low Description If a server sends two Strict-Transport-Security (STS) headers for a single connection, they will be rejected as invalid and HTTP Strict Transport Security (HSTS) will not be enabled for the connection. References Bug 1074642

# CVE-2017-7790: Windows crash reporter reads extra memory for some non-null-terminated registry values Reporter Xiaoyin Liu Impact low Description On Windows systems, if non-null-terminated strings are copied into the crash reporter for some specific registry keys, stack memory data can be copied until a null is found. This can potentially contain private data from the local system.

Note: This attack only affects Windows operating systems. Other operating systems are not affected. References Bug 1350460

# CVE-2017-7796: Windows updater can delete any file named update.log Reporter Matt Howell Impact low Description On Windows systems, the logger run by the Windows updater deletes the file "update.log" before it runs in order to write a new log of that name. The path to this file is supplied at the command line to the updater and could be used in concert with another local exploit to delete a different file named "update.log" instead of the one intended.

Note: This attack only affects Windows operating systems. Other operating systems are not affected. References Bug 1234401

# CVE-2017-7797: Response header name interning leaks across origins Reporter Anne van Kesteren Impact low Description Response header name interning does not have same-origin protections and these headers are stored in a global registry. This allows stored header names to be available cross-origin. References Bug 1334776

# CVE-2017-7780: Memory safety bugs fixed in Firefox 55 Reporter Mozilla developers and community Impact critical Description Mozilla developers and community members Gary Kwong, Christian Holler, André Bargull, Bob Clary, Carsten Book, Emilio Cobos Álvarez, Masayuki Nakano, Sebastian Hengst, Franziskus Kiefer, Tyson Smith, and Ronald Crane reported memory safety bugs present in Firefox 54. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. References Memory safety bugs fixed in Firefox 55