Merge pull request #1437 from HackTricks-wiki/update_Is_This_Bad__This_Feels_Bad___GoAnywhere_CVE-2025-_20250925_183320

Is This Bad? This Feels Bad — GoAnywhere CVE-2025-10035

src/SUMMARY.md

@@ -622,6 +622,7 @@
   - [Java JSF ViewState (.faces) Deserialization](pentesting-web/deserialization/java-jsf-viewstate-.faces-deserialization.md)
   - [Java DNS Deserialization, GadgetProbe and Java Deserialization Scanner](pentesting-web/deserialization/java-dns-deserialization-and-gadgetprobe.md)
   - [Basic Java Deserialization (ObjectInputStream, readObject)](pentesting-web/deserialization/basic-java-deserialization-objectinputstream-readobject.md)
+  - [Java Signedobject Gated Deserialization](pentesting-web/deserialization/java-signedobject-gated-deserialization.md)
   - [PHP - Deserialization + Autoload Classes](pentesting-web/deserialization/php-deserialization-+-autoload-classes.md)
   - [CommonsCollection1 Payload - Java Transformers to Rutime exec() and Thread Sleep](pentesting-web/deserialization/java-transformers-to-rutime-exec-payload.md)
   - [Basic .Net deserialization (ObjectDataProvider gadget, ExpandedWrapper, and Json.Net)](pentesting-web/deserialization/basic-.net-deserialization-objectdataprovider-gadgets-expandedwrapper-and-json.net.md)

src/pentesting-web/deserialization/README.md

@@ -438,6 +438,16 @@ javax.faces.ViewState=rO0ABXVyABNbTGphdmEubGFuZy5PYmplY3Q7kM5YnxBzKWwCAAB4cAAAAA
 
 If you want to **learn about how does a Java Deserialized exploit work** you should take a look to [**Basic Java Deserialization**](basic-java-deserialization-objectinputstream-readobject.md), [**Java DNS Deserialization**](java-dns-deserialization-and-gadgetprobe.md), and [**CommonsCollection1 Payload**](java-transformers-to-rutime-exec-payload.md).
 
+#### SignedObject-gated deserialization and pre-auth reachability
+
+Modern codebases sometimes wrap deserialization with `java.security.SignedObject` and validate a signature before calling `getObject()` (which deserializes the inner object). This prevents arbitrary top-level gadget classes but can still be exploitable if an attacker can obtain a valid signature (e.g., private-key compromise or a signing oracle). Additionally, error-handling flows may mint session-bound tokens for unauthenticated users, exposing otherwise protected sinks pre-auth.
+
+For a concrete case study with requests, IoCs, and hardening guidance, see:
+
+{{#ref}}
+java-signedobject-gated-deserialization.md
+{{#endref}}
+
 #### White Box Test
 
 You can check if there is installed any application with known vulnerabilities.
@@ -1146,6 +1156,7 @@ Industrialized gadget discovery:
 - Ruby 3.4.0-rc1 release: https://github.com/ruby/ruby/releases/tag/v3_4_0_rc1
 - Ruby fix PR #12444: https://github.com/ruby/ruby/pull/12444
 - Trail of Bits – Auditing RubyGems.org (Marshal findings): https://blog.trailofbits.com/2024/12/11/auditing-the-ruby-ecosystems-central-package-repository/
+- watchTowr Labs – Is This Bad? This Feels Bad — GoAnywhere CVE-2025-10035: https://labs.watchtowr.com/is-this-bad-this-feels-bad-goanywhere-cve-2025-10035/
 
 {{#include ../../banners/hacktricks-training.md}}
 

src/pentesting-web/deserialization/java-signedobject-gated-deserialization.md

@@ -0,0 +1,152 @@
+# Java SignedObject-gated Deserialization and Pre-auth Reachability via Error Paths
+
+{{#include ../../banners/hacktricks-training.md}}
+
+This page documents a common "guarded" Java deserialization pattern built around java.security.SignedObject and how seemingly unreachable sinks can become pre-auth reachable via error-handling flows. The technique was observed in Fortra GoAnywhere MFT (CVE-2025-10035) but is applicable to similar designs.
+
+## Threat model
+
+- Attacker can reach an HTTP endpoint that eventually processes an attacker-supplied byte[] intended to be a serialized SignedObject.
+- The code uses a validating wrapper (e.g., Apache Commons IO ValidatingObjectInputStream or a custom adapter) to constrain the outermost type to SignedObject (or byte[]).
+- The inner object returned by SignedObject.getObject() is where gadget chains can trigger (e.g., CommonsBeanutils1), but only after a signature verification gate.
+
+## Typical vulnerable pattern
+
+A simplified example based on com.linoma.license.gen2.BundleWorker.verify:
+
+```java
+private static byte[] verify(byte[] payload, KeyConfig keyCfg) throws Exception {
+    String sigAlg = "SHA1withDSA";
+    if ("2".equals(keyCfg.getVersion())) {
+        sigAlg = "SHA512withRSA";        // key version controls algorithm
+    }
+    PublicKey pub = getPublicKey(keyCfg);
+    Signature sig = Signature.getInstance(sigAlg);
+
+    // 1) Outer, "guarded" deserialization restricted to SignedObject
+    SignedObject so = (SignedObject) JavaSerializationUtilities.deserialize(
+        payload, SignedObject.class, new Class[]{ byte[].class });
+
+    if (keyCfg.isServer()) {
+        // Hardened server path
+        return ((SignedContainer) JavaSerializationUtilities.deserializeUntrustedSignedObject(
+            so, SignedContainer.class, new Class[]{ byte[].class }
+        )).getData();
+    } else {
+        // 2) Signature check using a baked-in public key
+        if (!so.verify(pub, sig)) {
+            throw new IOException("Unable to verify signature!");
+        }
+        // 3) Inner object deserialization (potential gadget execution)
+        SignedContainer inner = (SignedContainer) so.getObject();
+        return inner.getData();
+    }
+}
+```
+
+Key observations:
+- The validating deserializer at (1) blocks arbitrary top-level gadget classes; only SignedObject (or raw byte[]) is accepted.
+- The RCE primitive would be in the inner object materialized by SignedObject.getObject() at (3).
+- A signature gate at (2) enforces that the SignedObject must verify against a product-baked public key. Unless the attacker can produce a valid signature, the inner gadget never deserializes.
+
+## Exploitation considerations
+
+To achieve code execution, an attacker must deliver a correctly signed SignedObject that wraps a malicious gadget chain as its inner object. This generally requires one of the following:
+
+- Private key compromise: obtain the matching private key used by the product to sign/verify license objects.
+- Signing oracle: coerce the vendor or a trusted signing service to sign attacker-controlled serialized content (e.g., if a license server signs an embedded arbitrary object from client input).
+- Alternate reachable path: find a server-side path that deserializes the inner object without enforcing verify(), or that skips signature checks under a specific mode.
+
+Absent one of these, signature verification will prevent exploitation despite the presence of a deserialization sink.
+
+## Pre-auth reachability via error-handling flows
+
+Even when a deserialization endpoint appears to require authentication or a session-bound token, error-handling code can inadvertently mint and attach the token to an unauthenticated session.
+
+Example reachability chain (GoAnywhere MFT):
+- Target servlet: /goanywhere/lic/accept/<GUID> requires a session-bound license request token.
+- Error path: hitting /goanywhere/license/Unlicensed.xhtml with trailing junk and invalid JSF state triggers AdminErrorHandlerServlet, which does:
+  - SessionUtilities.generateLicenseRequestToken(session)
+  - Redirects to vendor license server with a signed license request in bundle=<...>
+- The bundle can be decrypted offline (hard-coded keys) to recover the GUID. Keep the same session cookie and POST to /goanywhere/lic/accept/<GUID> with attacker-controlled bundle bytes, reaching the SignedObject sink pre-auth.
+
+Proof-of-reachability (impact-less) probe:
+
+```http
+GET /goanywhere/license/Unlicensed.xhtml/x?javax.faces.ViewState=x&GARequestAction=activate HTTP/1.1
+Host: <target>
+```
+
+- Unpatched: 302 Location header to https://my.goanywhere.com/lic/request?bundle=... and Set-Cookie: ASESSIONID=...
+- Patched: redirect without bundle (no token generation).
+
+## Blue-team detection
+
+Indicators in stack traces/logs strongly suggest attempts to hit a SignedObject-gated sink:
+
+```
+java.io.ObjectInputStream.readObject
+java.security.SignedObject.getObject
+com.linoma.license.gen2.BundleWorker.verify
+com.linoma.license.gen2.BundleWorker.unbundle
+com.linoma.license.gen2.LicenseController.getResponse
+com.linoma.license.gen2.LicenseAPI.getResponse
+com.linoma.ga.ui.admin.servlet.LicenseResponseServlet.doPost
+```
+
+## Hardening guidance
+
+- Maintain signature verification before any getObject() call and ensure the verification uses the intended public key/algorithm.
+- Replace direct SignedObject.getObject() calls with a hardened wrapper that re-applies filtering to the inner stream (e.g., deserializeUntrustedSignedObject using ValidatingObjectInputStream/ObjectInputFilter allow-lists).
+- Remove error-handler flows that issue session-bound tokens for unauthenticated users. Treat error paths as attack surface.
+- Prefer Java serialization filters (JEP 290) with strict allow-lists for both outer and inner deserializations. Example:
+
+```java
+ObjectInputFilter filter = info -> {
+    Class<?> c = info.serialClass();
+    if (c == null) return ObjectInputFilter.Status.UNDECIDED;
+    if (c == java.security.SignedObject.class || c == byte[].class) return ObjectInputFilter.Status.ALLOWED;
+    return ObjectInputFilter.Status.REJECTED; // outer layer
+};
+ObjectInputFilter.Config.setSerialFilter(filter);
+// For the inner object, apply a separate strict DTO allow-list
+```
+
+## Example attack chain recap (CVE-2025-10035)
+
+1) Pre-auth token minting via error handler:
+
+```http
+GET /goanywhere/license/Unlicensed.xhtml/watchTowr?javax.faces.ViewState=watchTowr&GARequestAction=activate
+```
+
+Receive 302 with bundle=... and ASESSIONID=...; decrypt bundle offline to recover GUID.
+
+2) Reach the sink pre-auth with same cookie:
+
+```http
+POST /goanywhere/lic/accept/<GUID> HTTP/1.1
+Cookie: ASESSIONID=<value>
+Content-Type: application/x-www-form-urlencoded
+
+bundle=<attacker-controlled-bytes>
+```
+
+3) RCE requires a correctly signed SignedObject wrapping a gadget chain. Researchers could not bypass signature verification; exploitation hinges on access to a matching private key or a signing oracle.
+
+## Fixed versions and behavioural changes
+
+- GoAnywhere MFT 7.8.4 and Sustain Release 7.6.3:
+  - Harden inner deserialization by replacing SignedObject.getObject() with a wrapper (deserializeUntrustedSignedObject).
+  - Remove error-handler token generation, closing pre-auth reachability.
+
+## Notes on JSF/ViewState
+
+The reachability trick leverages a JSF page (.xhtml) and invalid javax.faces.ViewState to route into a privileged error handler. While not a JSF deserialization issue, it’s a recurring pre-auth pattern: break into error handlers that perform privileged actions and set security-relevant session attributes.
+
+## References
+
+- [watchTowr Labs – Is This Bad? This Feels Bad — GoAnywhere CVE-2025-10035](https://labs.watchtowr.com/is-this-bad-this-feels-bad-goanywhere-cve-2025-10035/)
+- [Fortra advisory FI-2025-012 – Deserialization Vulnerability in GoAnywhere MFT's License Servlet](https://www.fortra.com/security/advisories/product-security/fi-2025-012)
+
+{{#include ../../banners/hacktricks-training.md}}